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Software Raid 5 in WHS? RRS feed

  • Question

  • Does anyone know if software Raid-5 is supported in WHS like is is in Server 2003? My first impressions are that raid 5 is a little more robust than this new folder mirroring. I do see the need to have a redundancy solution that is more consumer friendly like folder mirroring, but I think that raid 5 is just going to perform better overall and have better redundancy.

    What do you guys think?

    Tuesday, February 27, 2007 2:49 AM

Answers

  • I'm not an MS employee, but I'd almost guarantee that this won't be supported, at least in this version.  There's an all-new drive technology being used, combining single-instance-storage and a new technology called "Drive Extender" that is used for the replication.  The disk usage scenarios are pretty strict in this version (e.g. you must have your primary drive be formatted and have 10GB used as the primary partition and the rest be data).  I don't think any customization will be supported, unless that customization is being done at the OEM level.  Hope that helps answer your question.  If I'm wrong, I'm sure someone will correct me shortly. 
    Tuesday, February 27, 2007 3:26 AM

All replies

  • I'm not an MS employee, but I'd almost guarantee that this won't be supported, at least in this version.  There's an all-new drive technology being used, combining single-instance-storage and a new technology called "Drive Extender" that is used for the replication.  The disk usage scenarios are pretty strict in this version (e.g. you must have your primary drive be formatted and have 10GB used as the primary partition and the rest be data).  I don't think any customization will be supported, unless that customization is being done at the OEM level.  Hope that helps answer your question.  If I'm wrong, I'm sure someone will correct me shortly. 
    Tuesday, February 27, 2007 3:26 AM
  • That was the impression I got, that they wanted to have people stay away from that. The release documentation in the install bundle warns you pretty strongly not to mess with anything in the Disk Management tool, and just to use the wizard, but I think I'll try anyway. : )
    Tuesday, February 27, 2007 3:53 AM
  • LOL! 
    Good luck with that. 

    Just thinking about how this works, I don't see how you can make this work, as WHS forces you to initialize the drive volume through it's interface, and if you reformat the disk, I don't think it will be initialized any more from within WHS.  It knows which drives it "owns" in the system, and which ones it doesn't, and won't use ones that it hasn't initialized.  You can have the drive in your system, and I'm sure you could share it out and stuff, but you won't be able to use it for backups and such.  But feel free to give it a go, and let us know what happens.
    Tuesday, February 27, 2007 4:01 AM
  • well, if you don't give it a go, then I'll give it a try next week!
    Tuesday, February 27, 2007 5:37 AM
  • I believe the mirroring is quite a bit more robust than RAID-5.  With a RAID-5 array, if you lose any two disks then your entire storage is destroyed.  With mirroring (let's assume you're mirroring everything), your data is only destroyed if a disk *and* its specific mirror disk dies. 

    So, for example, say you have a 4-disk array and 2 disks die.  In RAID-5, all your data would be destroyed, period.  With mirroring, there's only a 1/3 chance you'd lose anything - and in that case you'd only lose half your data.  (I don't know if the "half your data" part is true for WHS - but it is true in theory.) 

    Google and some other company each just published a report on their experiences with disk failures.  The results were pretty stunning: it turns out that a two-disk failure is *much* more likely than expected.  Also FWIW, Google doesn't use RAID arrays for most of their data storage.  They tend to rely on a simple double-mirroring model that's more akin to WHS. 

    The cost for mirroring's added robustness is disk space.  With RAID-5, there's only ever one disk dedicated to redundancy (so it's only 25% of a 4-disk array, and 20% of a 5-disk array).  With mirroring, you lose 50% of your disks to redundancy.  And don't forget that RAID-5 is actually a pretty complicated process - quite a bit is going on to "stripe" your data onto your disk array.  There's something reassuring with WHS utilizing more of a simple "xcopy" backup model.  (It also allows WHS to support non-identical disks, disk array growth, etc.)

    I don't mean to pan RAID-5.  It's a great technology, and has been around a long time.  But it definitely sacrifices robustness for more available disk space.  I personally would like to see WHS support *both* mirroring and RAID-5.  I'd like to use mirroring for most everything, but only RAID-5 for my huge DVD collection. 

    -andrew

    Tuesday, February 27, 2007 6:28 AM
  • Software RAID 5 works fine in WHS. It just isn't compatible with the WHS management console system.

    Personally I'm looking at using WHS as my new software RAID platform. Since the software RAID works exactly like any other compatible Windows OS, I can use WHS and get the added benefit of the new automated backup system.

    The share-based mirroring in WHS doesn't compel me at all. So I think I will RAID all my drives, and just use one drive to host WHS and backup data. (I'd just backup Windows+Users folders in this case)

    A good feature to suggest is allowing WHS to see software RAID arrays, so the "enthusiasts" can have their way like I mention above.
    Tuesday, February 27, 2007 8:01 AM
  • Okay, so I tested a mirrored raid array (software) of two 400 gig drives. The answer: no dice. While the mirrored array works fine under My Computer, WHS console see only the individual drives, and treats them independently. If you want to add them to WHS, you have to break the mirror and add them as separate disks.

    I guess I'm going the hardware raid route then, since I think thats a tad more failsafe then the folder mirroring. Folder mirroring is great for the targeted audience, but I'm looking to moving to a raid 5 array.
    Wednesday, March 7, 2007 2:07 AM