Absent…

Hey all!  I’m very sorry for the month long absence…  I have no excuse. 

I’m currently working on completing the next post in the series on the Holy Grail of home data storage.  I’ve actually completed my own build of the project that I was doing the review on, and I will be posting some photos of the finished (starter?) machine.

I will also be posting an article on an interesting comparison of the storage efficiencies between all of the systems I’ve reviewed.  I found it to be quite enlightening, and helped me finish deciding exactly what I was going to build.  I think you will all find it interesting as well.

In other news, we have the launch of Apple’s iPad coming up this week, and I will be watching that with much anticipation.  I own several iPod’s, one of which is an iPod Touch, which is closely related to the iPad, and I also own an iPhone, my new life partner ;)

Stay with me as I will be posting much more information soon!

Rollin' in the Carolina's 2010! Enjoy

It all started so innocently...



Then, the floodgates opened...



Then it started to get crowded...



People holding hands, having a good time...



Here's a group of men cruisiing. This is how it's done.



Before long, it really started to get crowded.



Here's some smooth mellow music. Many people decide to back this up a bit.



The DJ's were live-mixing all night long. The beat NEVER stopped.



Here is some more action from the sidelines



The group in the middle were having fun in their own way



Here's the women getting it on for the men to watch...



And here's the men's skate. One woman was really excited... right in my ear.



Enjoy!

Taking a closer look: Windows Home Server! Surely, THIS is the Holy Grail!

Today I continue my series on Home Network Data Storage: Looking for the Holy Grail.  So far, I’ve covered RAID-5 and Drobo.  Today we take a closer look at Microsoft’s offering: Windows Home Server.

What is Windows Home Server?

Windows Home Server (WHS) is a full-blown solution to the problem of protecting all kinds of data in the home.  It offers Best-In-Class automated backup of all of your Windows based desktop and laptop computers (and storage of said backup files), plus protected NAS style “shares” for all kinds of data from documents and programs to media like photos, music and videos. 

WHS is based on Windows Server 2003, which is a very mature and stable server operating system, but Microsoft has added the WHS layer which completely isolates the home user from having to touch the Server 2003 components at all… Everything is administered from a simple to use control panel that gets installed onto each Windows computer in the home.  This “layer” makes administering all of the features of the server so easy, that I could easily recommend a WHS to anyone who considers themselves NOT technical.  I’m even considering sending a few WHS machines to some family members as “gifts” ;)

How can I get it?

Windows Home Server is available as a turnkey solution.  You buy a WHS machine, take it out of the box, and plug it in.  These devices come with lots of room to grow.  Most have additional hard drive bays and you can add any size drive to it.  You can even add external USB hard drives when the internal bays fill up.

If you’re a DIY’er, you can now build your own WHS system.  When WHS was first released to the market, you could only get it by purchasing a turnkey WHS machine, but now Microsoft offers the OS as a stand-alone package that you can get for about $100.  They even offer the OS as a demo, so if you have old equipment laying around, you could download WHS and try it out for free.  Since it’s based on Windows Server 2003, much of our older computer parts laying around will work, and there’s a good chance drivers are available.

Ok, so is Windows Home Server the Holy Grail of Home Network Data Storage?  Let’s take a look.

Expandable

Windows Home Server offers perhaps the most flexible expandability of any home server solution.  Turnkey machines come with extra drive bays, and you can insert any capacity drive that you want.  Drive bays fill up?  No problem… just add more drives by USB or eSata.   You don’t have to buy another windows home server machine to add more drives – any generic “hard drive enclosure” will work.  Run out of USB ports?  Just grab a USB hub and keep going.

WHS will take any size drive you give it and add it to the “storage pool”.  WHS does not force you to decide which drive to store data on – all available storage space is presented as “Shares” - Folders instead of drives, and WHS automatically handles spreading files within those folders in a way that makes it completely invisible to the users.

The complete process is literally this simple: Go buy a new HD.  Slide it in or connect it.  Log into the control panel and click “add to storage pool”.  That’s it. Which brings me to my next point…

Simple

WHS is simple to  use.  Microsoft specifically designed WHS to be usable by anyone.  Turnkey solutions mean you don’t have to know how to build a server, and the WHS control panel makes managing the server a task easy enough that anyone could do it.  The FEATURE SET of WHS means that it is powerful enough that even long time I.T. professionals who manage million dollar systems at work come home to Windows Home Server machines.

To be honest, WHS is really unlike most other Microsoft products that you have have used in the past.  There’s a kind of iPod-like feel to it.  You don’t have to make a lot of decisions about how it should be setup.  You just plug it in and go.  There aren’t a of buttons or switches to touch.  The default “shares” are enough to simply start copying documents, music, videos, and photos onto it immediately.  The backup software configures itself automatically.  The connector software that you install on each Windows machine even puts a folder on your desktop to get to all the shares, and connects your Windows 7 Libraries to the shares.

My wife could do this.  I’m confident that she could handle every aspect of administering a WHS machine – from purchasing and setting it up, to the day to day operations of keeping it running, to managing problems such as replacing a failed hard drive and restoring backups.

Heck, my mother-in-law may be able to manage it.  That’s saying A LOT.

Reliable

WHS is built for reliability.  With WHS, your data can easily survive a failure of ANY HARD DRIVE in ANY COMPUTER in your home.

The backup service built in WHS is second to none.  It backs up the entire hard drive of every computer your home, and lets you restore either the entire hard drive, or individual files from any backup point in it’s backup database.

Data stored in the user shares are protected by a process called “Duplication”.  I mentioned earlier that WHS hides the concept of individual hard drives from the user, but believe me, WHS is VERY AWARE of the separate hard drives.  If you have more than one hard drive in a WHS, you can use duplication to make WHS make a copy of each file on separate hard drives.  This means that if any hard drive fails, exact copies of the data on that drive will also be stored on another drive. 

This duplication technology is very similar to RAID-1 Mirroring, except that with Mirroring, two physical hard drives must be equal in capacity (and ideally, speed).  With WHS, if you have one very large drive and several small drives, WHS can duplicate the data on the large drive across the many small drives.

Recent versions of WHS even offer a built in mechanism for backing up the server itself.  If you want, you can attach an external hard drive big enough to copy the entire server, and back it all up.  There are also online backup services available to backup the entire server to “the cloud” for true off-site storage.

Secure

Unlike the previous solutions I’ve reviewed (Drobo and RAID-5), WHS is a True Network Server platform, offering extremely robust security features.  Each user gets their own username and password to connect to the shares, and each share can be configured to allow each user to have full access, read-only access, or no access.

Password strength levels can be used to enforce good strong passwords, or none at all.  Plus, the connector software even tries to help make sure that the passwords users use to log into their Windows desktop computers match the passwords they use on WHS.

This gives me the confidence to know that I can store videos on my WHS and know that the kids cannot accidently delete videos when they’re done.

Low Power

WHS turnkey solutions are tuned for low power consumption.  Unlike the servers found in businesses, they use low power CPU’s and components to run as lean as possible. 

DIY system builders can use whatever parts they choose, but WHS has proven to run extremely well on Intel ATOM and other extremely low power platforms.

The one little thing that bugs me is that – since it’s built on Windows Server 2003 – you can’t get it to reliably spin-down the hard drives to save even more power.  Windows is constantly indexing files, or performing disk checks, or other various maintenance duties behind the scenes such that the drives are constantly being accessed every few minutes.

Quiet

Since WHS machines are designed to be very low power, they are also very quiet.  As expected, the hard drives themselves make noise, but since the CPU’s are very low power, they don’t need a lot of fans to keep things cool.

Fast

WHS wasn’t really designed to be a speed demon – that’s something you’ll really only find in a full RAID-5 type of machine tuned for maximum speed.  However, due to the way WHS stores single files each on one hard disk, the speed to read (or write) any given file will be limited only by the speed of that specific hard drive.

WHS only becomes slow when you use USB to attach an additional hard drive to the server.  Accessing data on that hard drive will, of course, be limited by USB speed.

Another factor that affects speed is how long it takes to recover from a failed hard drive.  With WHS, unlike a RAID system, data never has to be “rebuilt” from parity.  WHS literally stores a complete second copy of each file protected by “duplication” on another hard drive, so when one hard drive fails, the second copy is immediately available for access.

Cheap

WHS can be extremely inexpensive, or it can cost as much as you want to throw at it.  The equipment to get started is available in many forms, including boxes like the HP MediaSmart Server LX195, which is available for as low as $250 at the time of this writing.  I’ve even seen it for as low as $199 at one time.

The LX195 includes a 640 gigs of internal hard drive.  A plain 640g external hard drive by itself would cost you around $60-70 bucks.  (If you want Network Attachable, that’s going to run you a bit more).  Thus, the additional cost to get all of the features of WHS on top of that is actually remarkably low.

For DIY system builders, the fact that you can use almost any hard drive, motherboard, etc means that you can really choose what you want to spend.  The WHS OS itself is only about $100, and you can probably use much of the hardware that you already have retired or laying around.

When we talk about storage Efficiency, however, things get a little cloudy.  Duplication is not efficient, and WHS provides no (supported) option whatsoever to use RAID to protect your data.  WHS does provide the OPTION of using duplication.  You can easily create shares that are NOT duplicated – but then, those files are not protected against hard drive failure.

If you’re thinking of using WHS to store many gigabytes of downloaded video, then you need to expect to either 1) NOT use duplication to protect that data, or 2) spend double the capacity to store it. 

If, however, your video files are backed up to DVD on a bookshelf – such as they would be if you rip your own DVD library to disk - then you don’t NEED to use duplication on those files.  They’re already backed up.  If you needed to replace those, just grab your originals and re-rip them.  In this scenario, you only need to use Duplication on irreplaceable media like family home videos and photos.  Media that you could replace by re-downloading may not need protection.

Other Thoughts

I’ve mentioned in my other reviews that protected storage is NOT the same as backup.  The same sort of applies to WHS.  If you have important documents stored on WHS’s shares, and you don’t backup the entire server, then you could still easily delete those documents and loose them forever.  If, however, you store those important documents on the local hard drive of your Windows desktop PC, then WHS WILL protect those documents by virtue of having timely automatic backups of THAT machine.  If you delete those files, you could restore them from the backup that WHS provides.

Windows Home Server has a few other features I’ve not mentioned that make it of particular interest to my readers.  First, it includes an incredibly powerful media server that can stream music, photos and video to a variety of devices in your home.  All you have to do is copy the music into the appropriate share, and the server automatically makes them available to XBOX, PS3, O!Play, Roku, or whatever devices you have.

WHS also provides a means for remote access to your data when you’re away from home with it’s Remote access system.  It actually creates a secure website that you can log into remotely to not only access your files, but even control your home computers while you’re away.  Amazing.

I should also mention that Windows Home Server has many add-ons available that are developed  by third party software developers.  Many of the other solutions I’ve looked at can be hacked to do other tasks, such as share files via P2P/Bit Torrent, or serve files as an iTunes server.  What makes WHS different, however, is that the add-ons that are available are extremely easy to install, and don’t break the system.  The next version of WHS may even have an iTunes-like “App Store” to simply point and click to buy, download and install add-ons for various extra tasks.  Speaking of the next version of WHS…

Microsoft is working on the next version of WHS, and it has been leaked on the internet.  What have we learned from this?  We know now that the next version of WHS will be 64-bit only, meaning today’s lean 32bit processors found in most turn-key WHS machines will not be able to run it.  System builders, like myself, who are building WHS today should take this into consideration as we plan ahead.

Speaking of Microsoft, another consideration is that.. well, it’s Microsoft.  Many people hate massive corporations.  This is really up to personal preference.  Take it or leave it.  There are many other options available, but nothing I’ve ever seen so perfectly integrates with a home filled with a bunch of Windows desktop and laptop computers.  For example, since WHS formats all hard drives using NTFS, those shares are compatible with Windows features like Libraries and Search.  Other solutions that use Linux file systems are not fully compatible and even break library features.

Another benefit of using NTFS on the hard drives is that – unlike RAID-5 and especially DROBO, if you had to remove a drive from WHS, and it’s not completely failed, you can connect that drive to a Windows desktop computer and simply access the files on it.  This means that even if a drive DOES fail, you STILL might not loose any of your data, even without using duplication.

One last thought… I mentioned that WHS does NOT support RAID.  Well, it’s VERY unsupported, but some users have found ways to force raid under WHS to get the storage efficiency of RAID-5.  Unfortunately, by doing this, they loose the flexibility of adding any size drive any time they want.  Still, they get the backup features, media server, and ease of USE normally provided by WHS, but when it comes to dealing with issues, they are on their own.

Coming up next: I take a look at unRAID from Lime-Technology.  Where did THIS come from?

Taking a closer look: Drobo. Is this the Holy Grail?

Today, I continue my look into different options for Home Network Data Storage.  Yesterday, I examined RAID-5, which isn’t really a system, per se, but it’s important to understand it since most of the other options I’m going to explore are based on the concepts seen in RAID-5.

This time, I’m going to take a look at Drobo.

What is Drobo?

Drobo is a stand-alone external hard drive enclosure that holds up to 4 Sata hard drives in the most basic model, with more advanced models that hold 5 and 8 Sata drives.  Drobo’s claim-to-fame is that it is the simplest, most easy to use external hard drive solution available today, while also being one of the safest places to store your data.  It offers easy expansion by inserting up to four of literally any size (capacity) Sata hard drive you have laying around.

Simple

Drobo is very simple to use.  It’s so simple to use, in fact, that if my in-laws asked me what to buy for good safe data storage, I would immediately recommend the Drobo.  These are the same in-laws who recently called me to come fix their printer, and when I arrived, I found that it was out of paper.  It took me an hour just to explain how Tabs work in Firefox.  Plus, just to get them to use Firefox, I literally had remove every internet Explorer icon from their computer.

Drobo features a series of lights that indicate how full the storage space is.  When it gets too close to being full, it starts showing red lights to indicate it needs more space.  Next to each drive is a green light that indicates the health of the drives.  As long as all the lights are green, everything is good.

To increase the amount of storage in a Drobo, you literally just take out the smallest disk and replace it with a larger disk.  Drobo’s lights will even suggest which drive is the smallest to remove.  As long as you don’t take any more drives out until all the lights are green again, you don’t have worry about anything else.

That’s right… You don’t have to shut it down, or rearrange the drives, or open a control panel and tinker with configuration settings, or telnet into a root shell and enter special command line commands into a parity processor while crossing your fingers next to a tiki-god talisman.  You can literally treat it like an old fashioned VCR.  Need more space?  Take out the 2 hour tape and put in a 4 hour tape.

The awesome thing here is that the Drobo will automatically handle partitioning the drives, formatting them, adding it to the RAID array, and even moving your data around to the safest possible configuration.  You literally don’t have to do anything but give it the time it needs to do it.  And yes, you can use ALL of your data while it’s doing all that.

Expandable

Again, this is part of Drobo’s claim to fame.  They call this “BeyondRAID” technology.  It’s similar to RAID, but unlike standard RAID, Drobo lets you expand by inserting any size Sata hard drive that you have.  Drobo looks at the size of the drive, and automatically figures out the best way to integrate that extra storage into the storage pool that it makes available to the user.  If the Drobo is full of drives, and you still need to expand, you just take out the smallest disk and slide in a new bigger disk in it’s place, and the Drobo works automatically to incorporate the new disk into the storage pool.  This makes Drobo the ULTIMATE storage solution when it comes to expandability…

…right up until you have one more hard drive than will fit into it.  When you run out of space, and you have to take a drive out, now you have an extra drive.  Odds are that drive isn’t dead yet, either.  So, now what do you do?  You’ve got this extra drive laying around, and the Drobo is full!  Do you buy another Drobo?

Reliable

Drobo is, from what I hear, very reliable.  It takes very good care of your data, so you’re completely immune from loosing anything with one complete hard drive failure.  I’ve also heard that the hardware of the Drobo box itself is very high quality, and that much thought has been put into things like keeping the hard drives and other circuitry cool.

If I were to choose a Drobo for my data storage needs, I would feel pretty confident that my data is safe.

I should mention that I have read a few report of people loosing all of their data when using Drobo.  I’m not sure what’s going on with that. Perhaps it’s some kind of glitch, or massive user mistake, but while it does sound pretty extreme, most users of Drobo seem to be very happy with the devices.

Secure

Ok, this sounds too easy.  There has to be a catch, doesn’t there?  And there is.

Drobo is NOT a network storage solution.  It’s basically a super an external hard drive.  That means that you can’t just connect it to your network.  Drobo needs to be connected directly to a computer on your network.  From there, you can share the storage space with other computers on your network.

But, then how do you control access to the data?  Well, that depends on the computer it’s connected to.  A basic Windows computer offers workgroup file sharing that is actually pretty easy to configure, though it takes a but of understanding how it works, and a bit of planning as to how you want to set it up.  If you want more control, it is possible to turn off “simple file sharing” and do something more advanced, but I suggest grabbing a book on it, because it can get quite complex.

DroboShare

Ok, I lied.  You don’t really NEED to connect it directly to a computer, there is an extra device you can add called DroboShare.  DroboShare is basically a network interface controller for the Drobo that takes care of the important things like managing the Drobo’s file system and controlling user access to the data.

The biggest problem that I have with DroboShare is that, while DroboShare uses a gigabit Ethernet connection for maximum speed, it connects to the Drobo itself using USB.  It’s a lot like driving a Yugo on the autobahn, or trying to fill a swimming pool through a drinking straw.  Which brings me to my next point…

Fast

Drobo is not fast.  It is basically an external hard drive that connects to a PC using USB.  The latest version can connect to a PC using FireWire 800, but I’ve read that only really works for a Mac – Windows machines only really get to use it as FireWire 400.  The more expensive 5 bay Drobo S also features an eSata connection for the fastest throughput, but the problem with that is that still requires a desktop computer to run it, as the DroboShare only has the USB connections.

Now, admittedly, USB 2.0 isn’t horrible.  It’s fast enough to stream a movie to a media player.  The problem is this – is it fast enough to stream 3 movies to 3 different media players at the same time?  I have my doubts.

Low Power

Ok, I’ll be honest – I’m not really sure how a Drobo stacks up when talking about power efficiency.  I do know that it must keep all of the drives spinning to be able to access the data, but I have read that it can be put into standby mode as needed.  I don’t know if this is a sleep mode from which it can awaken automatically when data is needed.

What I do know is that if you decide to connect a Drobo to a full desktop computer, then you have to take the electrical usage of that computer into account when thinking of keeping your data available 24x7.

Quiet

Again, to be honest, I don’t know how quiet Drobo is.  I’ve heard it’s fairly quiet.  However, because it is primarily designed as an external drive solution that connects directly to a computer, it will tend to be more “in your face” with whatever noise it does produce. 

I suppose if you connect it with a DroboShare and stick it in a closet, it would probably be completely unnoticeable.

Cheap

Here’s the problem with Drobo.  It isn’t cheap.  A Drobo box, without any hard drives, costs as much as a small laptop computer at $350.   The more advanced models (that can hold 5 or more hard drives) easily costs as much as a very powerful gaming rig – around $700.  The DroboShare device is another $200.

That’s only part of the problem.  The other part of the problem is that Drobo’s are not exactly known to be EFFICIENT.  If you insert just one drive into a Drobo, you don’t even get to use all of the space on that one drive.  The Drobo uses half of that drive for “protection”.  I’m not quite certain how that’s supposed to work, since if you loose that one drive, you still loose it all, but that’s what the Drobo Calculator at Drobo.Com shows.

If you insert a second drive of the same size, then the Drobo automatically uses the entire second drive to protect the first drive.  This essentially is exactly the same as RAID-1, “Mirroring”, which is well known to NOT be particularly Efficient.  It’s very safe, but not efficient.  Still, your usable space is now equal to the entire first drive instead of just half of it, so it’s still an increase.

If the second drive is NOT the same size as the first drive, then it gets worse, because the Drobo will basically treat both drives as if they are the size of the smaller drive, and then do it’s Mirroring thing.  Any space on the larger drive above the smaller drive gets wasted as “Reserved for expansion”.  Oddly, if the smaller drive is less than half the size of the first drive, the Drobo’s storage pool actually gets SMALLER than with the larger drive alone.  Granted, it’s now protected from drive failure, but it is smaller.

Once you add a third drive, the Drobo starts to use Parity instead of Mirroring to become a little more efficient, but it still seems to suffer from the “Reserved for expansion” problem if the largest drive is significantly larger than the second largest drive.  Using the DroboCalculator, I tried to see what would happen with 2 500g drives and 1 1500g drive, and it shows the same amount of space as if I had used 3 500g drives.

Adding a fourth drive finally makes the Drobo start to be rather efficient.  But, then again, at this point, the box is full.  You simply can’t add a 5th drive unless you own the much more expensive “Drobo S” model.

Data Robotics, the makers of Drobo say that you should expect to loose an amount of storage equal to whatever the largest size drive is.  Honestly, that is to be expected.  What surprised me the most is that you should also strive to make sure the the SECOND largest drive is as close to the size of the largest drive as possible to avoid wasting space to “reserved for expansion”.

Other Thoughts

One aspect of the Drobo that worries me is that noone outside of Data Robotics Inc. really knows how Drobo works.  The details of “BeyondRAID” technology seems to be a very closely guarded secret.  I’ve read several articles on how people think it works, but I’ve also seen rebuttals from Data Robotics that are along the lines of “well, that’s close”.  What makes me worry about this is that – If the Drobo itself breaks down, you must replace it with another Drobo unit to get your data back.  This is similar to the problem with RAID-5, except that when my RAID motherboard died a few years ago, I was able to use just an add-in card with the same chipset to access my data.  With a Drobo, I’d be forced to acquire another Drobo box to be able to get my data back.  And again, they aren’t cheap.

One aspect of Drobo that really impresses the hell out of me is that unlike RAID-5, when you remove a drive from a Drobo, it immediately starts to rebuild the missing data in the remaining free space of the remaining drives.  If you have enough free space on those remaining drives, your data will eventually be fully protected again, even before you add the replacement drive back in.  Then, once you do that, it will move the data around again for maximum safety.  other systems I’ve read about will wait until you replace the failed drive, but Drobo doesn’t seem to want to wait around.

When I first heard of Drobo, I wanted one badly.  The idea of being able to use different size hard drives together in a RAID-5 like configuration, AND to be able to add those drives over time as needed seemed like a dream come true.  But, I must admit the slow speed, inefficient space usage, and high cost have really put me off.

If they sent me a review unit, I would be very happy to re-evaluate.  I’d like to know if the DroboShare could sustain streaming 3 video files simultaneously, one to my MediaCenter, one to my laptop, and one to my father-in-law’s O!Play Air.  I’d like to see how long it takes to rebuild data.  I’d also like to see how long it takes to rebuild data while streaming video files.  Also, I’d like to test it’s power usage and see how loud it is.

 

Next: Windows Home Server – perhaps that’s the HOLY GRAIL?

Taking a closer look: RAID-5. How does it measure up?

In my last post, I explored the Holy Grail of Home Network Data Storage.  Now, let's take a look at some specific solutions and see how they measure up.

First, I want to take a generic look at RAID, since most of the other solutions I will be discussing are decended from RAID.

What is RAID?

RAID is an acronym that stands for "Redundant Array of Inexpensive Disks".  The idea behind RAID is to use multiple hard drives to store data in a way that either increases speed, or increases reliabilty... or both at the same time.

RAID is actually more of a concept that includes many different sub-categories.  There are many different "Raid Levels" such as RAID-0 which is designed purely for speed, RAID-1 which is designed purely for data protection, and RAID-5 which, with enough physical harddrives, combines both speed AND data protection.

For our discussion about the Holy Grail of storage, I will focus mainly on RAID-5 because RAID-0 is sorely lacking in the RELIABLE department, and RAID-1 fails to impress in the CHEAP factor.

RAID-5 uses a combination of "striping" and "parity" to increase both speed and reliabilty of data. 

Understanding Striping

Striping is a way of spreading data across multiple drives to increase speed.  Here's one way to think of it:  Suppose you have a house full of furnature, and you need to move across town.  You have a truck that can hold a certain amount of furnature.  Assuming your packers and loaders are VERY fast, the speed limit in town really limits how fast you can move your stuff from one location to another.  You can greatly increase the speed at which you can move your stuff if you add more trucks!  If you have 3 trucks moving the furnature, the job gets done MUCH faster.

Hard drives are kinda similar to this idea.  The most limiting factor of a hard drive is the speed at which it can read data off the disk and pump that data through it's controller to the network card, or wherever it's needed.  With today's hard drives, it really boils down to how tightly packed is the data on the surface of the disk, and how fast is the disk spinning.  When you use multiple physical hard drives and spread the data between them, you can get more data moved faster, just like using more trucks.

Understanding Parity

Parity is a way of adding extra bits to existing data to create a way to rebuild missing bits.  It can be hard to wrap your brain around how it actually works, but I can make it simple.  Consider the following excersise.

Imagine we have 3 Bytes of data, and each byte is stored on it's own hard drive.  Bytes, as you know are made up of 8 bits.

For each ROW, add up the bits.  If the result is an odd number, ADD 1 to the row.  If the result is an even number, add zero.  The goal is to make sure every row adds up to an even number.  For example, the first row is 0+0+0 which adds up to 0, which is an even number, so we write down a 0.  The fifth row is 1+1+1, which adds up to 3, an odd number.  We add a 1 to bring it up to 4, which is an even number.

Now, imagine one of the hard drives bites the dust.  We've just lost all 8 of the bits on that hard drive.  But, with Parity, we can "REBUILD" the missing data.

Now, imagine adding a new empty hard drive, and do the same excersise again - For each row, add up the bits and either add 1 or add nothing to make sure each row adds up to an even number.

As you can see from this simple excersise, we can very easily determine the missing data by using parity along with remaining data to figure out what was missing.  It works the same way in a computer, except that the CPU uses the XOR math operator to add up the bits much more quickly.

RAID-5 - how does it measure up?

Ok, now let's take a look at using RAID-5 as a storage solution for a home network.

Expandable

RAID-5 is NOT very good at being expandable.  The problem with RAID-5 is that while you can use many hard drives, they must all be the same SIZE, and the must be all together from the start.  If you have hard drives of multiple sizes, the array can only use as much space on each drive as the smallest drive.  Any extra space on the other drives is wasted.  Also, you cannot add another hard drive to a RAID-5 array without rebuilding the array.  This usually means you need to take all of the data out of the array(backup), then rebuild it from scratch including the new drive, then move all the data back into the array.

There are certain hardware RAID controller cards that actually can handle adding drives to an array, but these tend to cost alot more, which goes against the CHEAP factor, plus it's often quite a complex task to actually make the change since much of it must be done by hand.

Reliable

RAID-5 is very good at being reliable.  In an array with multiple drives, you can loose one drive completely, and still not loose any of your data.  You can add a replacement drive back into the array, and the controller hardware or software can rebuild the missing data using the parity.  As a bonus, the controller card can even calculate the missing data on-the-fly.  If you need to access your data while a drive is missing from the array, the controller can perform the parity calculations on-the-fly to create the missing data and serve it to you, even without it existing on a physical drive.

Fast

RAID-5 tends to be pretty good at being fast.  At least, the potential is there.  It really depends on the speed of the Controller that is controlling the hard drives.  If the controller has dedicated hardware circuitry to handle the calculations for parity, then a RAID-5 system can be incredibly fast, and can easily be faster working together than any of the single drives working alone - while still being safe.

 

Ok, let's stop for a moment.  RAID-5 isn't really a "system", it is a concept that would be used in building a system.  If we want to use RAID-5 to provide data storage on a home network, we would still have to use it as a feature on a server, or a stand-alone Network Attached Storage device.  The choice we make here determines the following several factors as a network storage device.

 

Secure

RAID-5 itself has no security.  It's the operating system of the machine running the RAID array that determines the security.  You could build a Windows Server 2008 machine with some AWESOME security, and control access to every single file on the system.  Or, you could buy a cheap NAS enclosure with really badly implemented (or no) security.

Low Power

Again, how much power a system uses depends on the whole of it's parts, but thinking specifically of just the RAID-5 array, one important thing to remember is that when you access data on the array, ALL of the hard drives in the array must be spinning.  In fact, I would not expect to spin-down the hard drives of a RAID-5 array ever.  There is potential for a low-power system if you select the right drives and other hardware.

Quiet

Likewise, how Quiet a system is depends on the whole of it's parts, but taking into account the number of hard drives, and the fact that they must spin continuously, you have to consider fans to keep them cool.  The potential is there for a quiet system, depending on the case and the fans.

Cheap

RAID-5 has great potential here.  You see, the problem with RAID-5 is that it requires at least 3 hard drives just to bring it into existance, and if you want to eventually have more drives, you really should start with those from the beginning.  So, there is an initial start-up cost investment to deal with.

The Cheap factor also includes Efficiency, and this is where RAID-5 shines.  You can get full data protection from any 1 hard drive crash for the cost of one of the drives.  Each additional drive you add after the first one adds you that much space.  If you have 3 500g drives, you loose 500g to safety, and can use 1000g.  If you add another 500g drive (at the start), you get 1500g of usable space.  As you consider starting with even more drives, the cost per usable gig of storage goes down.

There are a few other factors to consider - again, the cost of the system depends on the whole of it's parts.  And to do RAID-5 really well, you should get a dedicated RAID controller card to connect the drives to the system.  Those pretty much start at roughly $300 from what I've seen.

Simple

Here's where it all falls apart.  You see, if we consider RAID-5 as a stand alone concept, then we must assume that you know what to do with it.  You will need to build a system to house it, or you'll need to go buy a box of some kind to build it in.  I'm not talking about a turn-key system, I will explore those in detail in my new few posts.

A well built RAID-5 system would be simple to maintain, but very complex to build initially.  My wife could not build one, but if the machine had hot-swap bays, she could easily swap out a dead hard drive.  Then again, that all boils down to - how much are we willing to spend on it to start with?

Bottom line here is this: I can’t just turn to my wife and say “RAID-5.   GO!” and expect her to know WTF I’m even talking about.

Other Thoughts

As will all of the "systems" I'm planning to discuss, there will always been some additional considerations to think about.  These are the litle gotchas that you need to consider outside of the other factors mentioned above.

First, I will take the opportunity again to point out that RAID is NOT the same as backup.  If you have a healthy RAID array, and you (or someone you love (or a virus!)) accidently deletes a file, there is no protection from that at all.  The RAID array will happily delete the file, just exactly like a single ordinary hard drive would.  If you overwrite a file, it's gone.  BACKUP YOUR DATA.

If you loose one hard drive from an array, the array is then unprotected until you replace the missing drive and let it rebuild.  During this time, if you were to loose another hard drive, you would loose all of the data on the array.  The fact that RAID-5 continues to run with a failed or missing hard drive increases the temptation to USE the system in that state, which in turn increases the risk that something could go wrong during that time.  If you want ultimate safety, you would shut the system down when it looses one drive.

In a RAID-5 system, you really need the whole system up and running to access the data.  If you had to take the system apart, you would not be able to get anything out of the drives by hand because the files are stretched across all of the drives, and only the chipset of the RAID controller knows exactly how to reconstruct the data.  If you use a rare RAID controller card, and it dies instead of one of the hard drives, you may loose all of your data if you can't replace the controller card.  One might consider deliberately using a controller with a common chipset in case replacement is ever necessary.

 

Coming up next:  Drobo!