A reminder of the advantages of Drive Extender over RAID

by Alex Kuretz on April 10, 2009 · 9 comments

in Windows Home Server

The MediaSmartServer.net site (as well as the handful of other sites I host for various friends and family) runs on a Linux server hosted in a data center (powered largely by windmills in Wyoming!). In order to safely back up all the important information collected on this site, such as the helpful and informative Wiki articles and all the forum posts, I found it necessary to build a Linux server to do nightly backups of the Web Server, perform service monitoring and alerting should the Web Server have issues, and a few other various activities. This server is running in my home, has a 2 x 160GB hard drive RAID 1 array to mirror all the data, and has been working great for a couple of weeks.

This evening I checked the server and found that one of the hard drives was not working correctly and the RAID array was running in a degraded state. I could see that the server was able to detect that both drives were in the system, but one of them was showing an incorrect number of cylinders which was causing problems with the OS accessing the partitions. I tried adding the “failed” (but obviously working) drive back into the array, with no luck. I tried removing the partitions from the drive using “fdisk” and manually configuring the cylinders to the number that I knew was correct for this drive, and this also did not work. Out of desperation I even rebooted the server, but there was still something wrong with this drive.

I should state that I’m no System Administrator, and while I’m quite comfortable running and using Unix systems there are some areas that I just don’t have much experience, and configuring hard drives and RAID arrays is one of them. Since I don’t know all the right tools in Linux, I popped the drive out of the server, put it into one of the handy screw-less drive trays from HP, and slid it into my MediaSmart Server. I then found the drive in the Disk Management section of the Windows Computer Management console, deleted the partition, created a new partition and did a full format. I also ran a full chkdsk on the drive to see if there were any hardware issues with it. A few hours later the disk checked out ok, I put it back into the Linux server, and added it back into the RAID array (which is still rebuilding as I write this blog entry).

The RAID array rebuilding as I write this blog entry.

The RAID array rebuilding as I write this blog entry.

This events of the evening has left me thinking quite a bit about what a great experience the Drive Extender technology of Windows Home Server provides to the end user. There would have been no need for the numerous cryptic commands I had to type tonight creating partitions and specifying file system types, because Drive Extender will happily accept any sized drive I care to connect to the Windows Home Server. Out of the box Windows Home Server would have automatically informed me when a disk in its storage pool failed (and even sent me an email or text message using my Remote Notification Add-In), while the only reason I knew about the failure on my Linux server tonight was because I was in the process of configuring automated monitoring and alerts. And if the server hardware were to fail, since Drive Extender utilizes the NTFS file system I could have inserted that drive into any computer and retrieved my data off of it, something that would not have been possible with the disks in my RAID array.

This is probably leading some of you to question why I even have a Linux server running at home. While I’m a huge fan of Drive Extender and Windows Home Server, there are certain applications and environments where it is not the best fit. In order to easily and securely back up MediaSmartServer.net I need tools like rsync to efficiently and easily copy files across the internet, I need ssh to secure and encrypt the transmission of this data, I need cron to schedule these tasks, and I need a platform that makes it easy to install, deploy, and develop the applications that power this site. Admittedly I’m going way beyond the intent of Windows Home Server with this scenario, which is why I chose another purpose-built system to perform these tasks.

After a couple of years using a home server, it can be easy to take for granted the ease of use that Windows Home Server provides us. But every now and then something happens that reminds me that behind the easy to use interface is some powerful technology and tonight was one of those moments.

The Windows Home Server team blog has a good article on why RAID is not a consumer technology that is worth a read. What are your thoughts on RAID versus Drive Extender?





Article by

I'm Alex Kuretz, and I'm the founder of MediaSmartServer.net. I was the Lead Test and Integration Engineer at HP for the MediaSmart Server until April 2008 when I moved on to other opportunities outside HP. I've kept active in the Windows Home Server community, creating several add-ins and helping users make the most of their Home Servers.


{ 9 comments }

JohnBick April 10, 2009 at 7:43 am

I think both RAID and DE have their place. RAID does offer the ability to improve overall data access performance through striping and, in more high-end uses, that is very important. But when one looks at DE vs RAID-1 (mirroring) I just do not see any advantage to RAID.

What would be VERY nice would be to have DE built into Windows 7 to provide the duplication benefits at the client level. Granted, in some situations this may be seen or used as a replacement foe WHS, but it would provide the consumer with reliability and expandability characteristics that would, I believe, encourage expansion of use (i.e., more data storage) bu the less technically oriented consumer.

Phil April 10, 2009 at 11:52 am

As a hobbyist, I can’t speak for the ramifications, but why not use a little (or a lot) of both, now the WHS DE is available? I have been considering RAID 0 or 5 for my gaming PC for a while. Since the PC uses DDR memory (and no more than 2.5 GB, right now), there’s a lot of disk accessing going on, which can slow down your gaming experience. Even with a system drive and a data drive.

So my thought is, why not create a RAID 0 data drive and protect it with MSS full computer backups? That gives you speed [i]and[/i] redundancy, right? Since the MSS is a home “appliance” (ie. I don’t have any hard-core server needs) this seems like a good match…

Alex Kuretz April 10, 2009 at 11:58 am

Phil I think your suggestion of striping (RAID 0) the disks on the PC for improved disk performance makes a lot of sense when you’ve got the awesome PC Backup Software feature of Windows Home Server. In a strict RAID 0 scenario you’re taking a lot of risk as either disk failure can cost you your system, but when that RAID 0 is backed up to Windows Home Server and so easy to restore then that risk is negated.

John, I guess the primary value proposition I see with putting DE into a client OS would be strictly for the auto-sizing partitions, so that when a user needs more space they just add a drive and don’t have to remember which partition or disk the data is stored on. However, this somewhat conflicts with the idea of the Home Server which provides centralized storage, access, and security of your data.

John Reed April 10, 2009 at 1:39 pm

Alex – I’m confused… isn’t Drive Extender (DE) at the heart of Home Server?

… In my opinion the combination of WHS and DE are currently the closest solution to my Home Server needs. In my perfect world DE would have built-in fully redundant capability. As it’s my understanding not all of the system components in WHS are redundant out of the box. Something which had Drobo like redundancy, where you can literally pull any drive at any time and replace it with a new one without worrying about data loss (understanding that you can only do this with one drive at a time), as well as having all of the current HP Media Server goodness like automated backups, media streaming, windows compatibility, remote access, etc.

my 2 cents

Alex Kuretz April 10, 2009 at 1:55 pm

Hi John Reed,

Yes, Drive Extender is the storage technology used in Windows Home Server, and I agree that they are indeed currently the best solution for a Home Server. There is of course the opportunity to improve by also making the operating system redundant and immune to drive failure.

As I mention in the article, my use of a RAID array in a Linux server is far beyond the needs of the average home server user, and the extra technical skills and experience needed to configure and keep it running made me appreciate the value that WHS and DE provides.

If I’m missing your point, please let me know!
Alex

john reed April 13, 2009 at 11:29 pm

I think you hit my point… I misunderstood you when you said:

“…John, I guess the primary value proposition I see with putting DE into a client OS would be strictly for the auto-sizing partitions, so that when a user needs more space they just add a drive and don’t have to remember which partition or disk the data is stored on. However, this somewhat conflicts with the idea of the Home Server which provides centralized storage, access, and security of your data…”

I just re-read it (for the 3rd time) and now get it… :)

Alex Kuretz April 14, 2009 at 8:50 am

Sorry for the confusion, it sounds like we’re in sync now, but to reiterate I was advocating for DE to remain on the server for long term data storage and protection.

John Reed April 14, 2009 at 9:41 am

Totally agree, and I think we both agree that some improvement could be made ;)

Guillaume Boudreau December 16, 2009 at 2:22 pm

Hi there.

(I realize this post if quite old, but I found it when researching for WHS Drive Extender alternatives, so I thought others might find it too.)

I just posted the first public version of Greyhole – Easily expandable & redundant storage pool using Samba.
It’s an open source implementation of something like Drive Extender, in Linux.

If any of you guys want to help me test it, I’d be happy to get some help in finding bugs.
Once it’s been tested enough, it should become a nice alternative to WHS Drive Extender! :)

You can read the details here:
http://www.pommepause.com/blog/2009/12/greyhole-easily-expandable-redundant-storage-pool-using-samba/

Cheers.

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