locked
Do snapshots work without folder duplication? RRS feed

  • Question

  • Hi guys,

    I orignally shied away from WHS because I was worried about stability.  I initially set out to build a linux file server that would do nothing but serve up files.  For a variety of reasons, I've started looking into using WHS.  Hardware wise, I have a 3ware 9650SE-16 device controller with 8 WD2002fyps 2TB drives attached in a RAID6 setup.  I have a friend with a WHS with 16 2TB drives and think it's crazy that he loses half to folder duplication.  Sure, you can turn it off, but a drive takes a dump, you're screwed.  I also refuse to use my raid card as an expensive simple SATA controller =)

    I've read that WHS can't handle a change in size of an attached hard drive, so I went down the auto-carve route the 3ware card offers.  I set the carve size to be 1TB so any time I add disks to the raid volume, a new 1TB volume gets exposed to the OS and will only attach full 1TB volumes (will leave the new "remainder" volumes alone until they hit the 1TB size).

    Does anyone see a problem with this approach?  I've abstracted away from WHS the possibility of a drive failure and I still retain the speed of the hardware accelerated RAID.

    Lastly, I haven't looked into the snapshot of files too closely, but is this feature disabled if I don't have folder duplication on?

    Thanks!

    Friday, April 16, 2010 3:02 PM

Answers

  • If by "snapshot" you mean Previous Versions/VSS copies of files, then you should readthis KB article . Long story short, they don't work properly on Windows Home Server due to the way Drive Extender operates with files and disks.

    As for your plan to use RAID, I see no reason why it shouldn't work. However, itis unsupported, and Microsoft has been pretty clear that it won'tbe supported. In addition, it's pretty likely that you won't see the level of performance improvement you might expect, since Drive Extender adds overhead and as soon as you have multiple drives (even logical volumes on a RAID array) DE will become involved in your file management.


    I'm not on the WHS team, I just post a lot. :)
    • Marked as answer by ekological Saturday, April 17, 2010 3:14 PM
    Friday, April 16, 2010 4:08 PM
    Moderator

All replies

  • If by "snapshot" you mean Previous Versions/VSS copies of files, then you should readthis KB article . Long story short, they don't work properly on Windows Home Server due to the way Drive Extender operates with files and disks.

    As for your plan to use RAID, I see no reason why it shouldn't work. However, itis unsupported, and Microsoft has been pretty clear that it won'tbe supported. In addition, it's pretty likely that you won't see the level of performance improvement you might expect, since Drive Extender adds overhead and as soon as you have multiple drives (even logical volumes on a RAID array) DE will become involved in your file management.


    I'm not on the WHS team, I just post a lot. :)
    • Marked as answer by ekological Saturday, April 17, 2010 3:14 PM
    Friday, April 16, 2010 4:08 PM
    Moderator
  • Thanks for the info, Ken!  I saw that earlier when I searched but saw that the timestamp was in Jan 2009!!!  I thought if it was a known issue back then, it might be resolved by now...

    I don't mind if Microsoft doesn't support hardware raid.  It's all abstracted away from the software and so long as the drivers work, I'm a happy camper.  As for performance improvement, my friend's server consisted of a Areca adapter (I think a ARC-1300ix-16) connected to 16 WD20EADS disks.  I believe the CPU was a xeon dual core variety, but I'm not sure of the exact one.  When trying to copy a very large file to the server over a gigabit ethernet network, I obtained the following activity:

    http://www.pbase.com/ekosan/image/123664724

    You can see equal periods of ~50MB/sec followed by very little activity.  His setup had the duplication turned on so I can only imagine the server was trying to copy the data to the other drives when there was no network activity.

    My server is as listed in the first post except for testing purposes, I only created a raid volume consisting of three disks because I didn't want to wait for 10TB to initialize =)  The CPU is an Intel 2GHz Celeron single core processor.  I did see CPU activity go up during the copy which is probably the overhead from the drive extender.  I actually think the bottleneck now is the source computer which has three 1TB drives using the Intel fakeRAID.  I'll have to try with my laptop over a wired gigabit connection using the SSD =)  At any rate, the peaks in the graph translate to roughly 100MB/sec and the line in the middle translates to 50MB/sec.  So I'm always at least better than my friend's setup and oftentimes have higher throughput and there are no periods of inactivity:

    http://www.pbase.com/ekosan/image/123664727

    So far, so good...

    Friday, April 16, 2010 6:01 PM
  • If you're happy, I'm happy. :)

    We don't talk about RAID here much (beyond "it usually works but it's unsupported") because Microsoft is pretty adamant about it having no place in their product vision. See e.g the Drive Extender techinical brief and this blog post for Microsoft's position. I'll note in passing that I agree with Microsoft's position on the consumer side, and disagree (to an extent) on the technical side.


    I'm not on the WHS team, I just post a lot. :)
    Friday, April 16, 2010 7:16 PM
    Moderator