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RAID Controller Migration

Apothe0sisApothe0sis Have you ever questioned the nature of your reality?Registered User regular
Hi All,

Let's talk RAID Controllers. If I have a RAID controller which is currently at capacity and want to install a controller with a bigger capacity. My concerns are as follows:

Is there anything controller specific with regard to how the RAID volumes are created? We're specifically talking about RAID1 in this case.

Can you simply unplug them from one controller and plug them into another? If I take one of the disks within a RAID1 volume and try to access it like a regular disk, can that be done? Will it RUIN EVERYTHING? Are there any guidelines here?

Tide goes in. Tide goes out.
Es-annon NEVA 4GET

Posts

  • AlectharAlecthar Alan Shore We're not territorial about that sort of thing, are we?Registered User regular
    I'm no expert, but I know that many hardware RAID controllers use specific meta-data to maintain the array, at least when you're using a parity setup (RAID 5 or 6, usually). This is usually specific to the chip used in the RAID controller and thus migrating the drives over would require them to be either re-formatted, or for the new controller card to be based on the same chipset.

    I'm not sure if something similar is utilized in mirroring setups. My assumption would be no, as I can't think of a reason RAID 1 would require the same kind of meta-data. As long as there is no striping (that is, you're not using RAID 1+0) you should be able to access the contents of any single drive without issue if the OS you're using to access it supports the filesystem on the disk.

    Aside from the 1st paragraph, I'm not 100% on the stuff above, so please don't take just my word for it. All that said, you might consider going with a software RAID in the future. Most controllers have a JBOD mode you can use that will pass through instructions from the software-based RAID, and if you're using a relatively modern processor the load is really quite minimal for a small array. Also, in my experience they migrate much more easily.

  • electricitylikesmeelectricitylikesme Registered User regular
    The controller will use some type of metadata, which likely means the new controller will want to re-initialize the disks even if they're used in RAID1.

    Basically, this is why you should almost never use hardware RAID, since the RAID card itself becomes the point of failure.

    My advice is, since you're expanding the array and will need new disks to make sure you get enough capacity to backup the old volumes first before you try anything.

    And, if you can, switch to some type of software-RAID - the CPU overhead is negligible from the common modes these days. Both Windows and Linux do a great job here.

    That said: there is software specifically designed for recovering the data and volumes out of various RAID failures, and in mirror mode at least you could probably just run TestDisk to build a normal partition table around the RAID volume.

  • QuantuxQuantux Registered User regular
    edited March 2013
    Depending on the controllers involved, you may be able to import raid config from the drives to the new card. I know this can be done with the standard HP/Dell cards, but if we're talking mobo sata-raid, then probably not. Get into the raid config on your next boot and see what options you have.

    Quantux on
    PSN/Steam - Quantux

  • Apothe0sisApothe0sis Have you ever questioned the nature of your reality? Registered User regular
    Quantux wrote: »
    Depending on the controllers involved, you may be able to import raid config from the drives to the new card. I know this can be done with the standard HP/Dell cards, but if we're talking mobo sata-raid, then probably not. Get into the raid config on your next boot and see what options you have.

    We are talking about dell cards, moving from a perc200 or something to an h700.

    Unfortunately it isn't a Linux or windows box, but a VMware box which is running with local storage - the best solution is to get a SAN, but that is not on the cards right now.

    Tide goes in. Tide goes out.
    Es-annon NEVA 4GET
  • Le_GoatLe_Goat Frechified Goat Person BostonRegistered User regular
    Apothe0sis wrote: »
    Can you simply unplug them from one controller and plug them into another? If I take one of the disks within a RAID1 volume and try to access it like a regular disk, can that be done? Will it RUIN EVERYTHING? Are there any guidelines here?
    Unless both controllers are configured the same way, I don't think you can pull HDDs from one RAID array and put them in another RAID array and expect them to behave the same (specifically between RAID types).

    However, I am pretty confident that you can pull drive from a RAID1 configuration and use it outside of that array as a typical disk. Afterall, it's just a carbon copy of the other disk in the array. As long as it is not placed within another RAID array, it should function normally. Good news is that it is easy to test. You can easily just add a newly formatted disk into the original RAID1 and rebuild the array, then test the disk you removed without fear of losing what was on the original array.
    Alecthar wrote: »
    I'm no expert, but I know that many hardware RAID controllers use specific meta-data to maintain the array, at least when you're using a parity setup (RAID 5 or 6, usually). This is usually specific to the chip used in the RAID controller and thus migrating the drives over would require them to be either re-formatted, or for the new controller card to be based on the same chipset.
    I believe that Alecthar is correct here. One of the problems with RAID is that you really cannot change the properties. If you do wish to change how the RAID operates, it requires completely formatted drives, much like how multiple partitions on a single drive behave. However, I have had success in the past of cloning a drive onto a newly formed (and larger) array. If you're talking terabytes, then cloning may not be very viable of a solution.

    While I agree that being insensitive is an issue, so is being oversensitive.
  • QuantuxQuantux Registered User regular
    edited March 2013
    After a quick search looks like it is doable (maybe even supported by Dell):
    It is quite easy - power down, replace the controller, power up, if prompted with a foreign configuration, import the foreign configuration in the CTRL-R utility:
    Virtual disks that are created on the PERC 6 and H200 family of controllers
    can be migrated to the PERC H700 and H800 cards without risking data
    or configuration loss.

    http://www.dell.com/support/Manuals/us/en/04/Product/poweredge-rc-h700

    From here

    My experience with Dell raid is limited to the perc4/6 series running raid5, but I know I've had to move an entire array before and used the import foreign config quite successfully (though that's between two identical controllers).

    EDIT: Just had a thought, if you want to be on the safe side, start with one of the drives, import foreign config from that, boot up and verify it's all good, then pop in the second drive and let it rebuild like normal.

    Quantux on
    PSN/Steam - Quantux

  • Apothe0sisApothe0sis Have you ever questioned the nature of your reality? Registered User regular
    Well, for those of you who are interested.

    Migration did not go according to plan, the server refused to boot once the card was installed. As it turns out the card we were told to order was not complete in its information - we got an h700 internal adaptor, we needed he h700 integrated.

    Danced around with dell pro support for a few hours, they thought it should work. It didn't. Upgraded the bios etc... Still no dice.

    At 2.30AM someone new came on shift, declared the card incompatible, and gave us the "correct" part number. Parts and accessories claim that part number doesn't exist. 24 hours later we get a quote for another part, with the exact same description as the card we got, but half the NVRAM for $200 more. The next gen card for the next gen of PE servers which is specified as an integrated card costs less than half that. Still awaiting a response as to what is going on.

    Plus, of course, in classic dell fashion, no part numbers are mentioned on the quote, so who knows what's going on there.

    These people are maniacs.

    Tide goes in. Tide goes out.
    Es-annon NEVA 4GET
  • BigityBigity Lubbock, TXRegistered User regular
    You need a sales rep. We don't put up with that kind of crap.

    Of course, we buy enough computers and stuff for them to care, so that may be an issue.

    76561198017303226.png
  • Le_GoatLe_Goat Frechified Goat Person BostonRegistered User regular
    I wish the forums had a "shake fist of anger" button, because I would have used that.

    Dell support used to be amazing, but then they started getting extremely picky about how to handle support call and replacements. @Bigity may be right. A sales rep would be able to weed through all of their internal contacts to figure out what you need instead of relying on support to bounce around ideas off each other. If that fails, you speak to their supervisor. That's one of the only good things about sales people: if they fuck up, their boss is quickly notified and you get your service... most of the time.

    While I agree that being insensitive is an issue, so is being oversensitive.
  • Apothe0sisApothe0sis Have you ever questioned the nature of your reality? Registered User regular
    We have a sales rep.

    He's totally pants.

    It is my general experience that things go smoothly when we are buying new machines.

    They go to hell when we want to buy parts.

    Tide goes in. Tide goes out.
    Es-annon NEVA 4GET
    GethLe_Goat
  • Le_GoatLe_Goat Frechified Goat Person BostonRegistered User regular
    Sorry for being a bit off topic, but what does that mean: "he's totally pants"? I've never heard that before.

    While I agree that being insensitive is an issue, so is being oversensitive.
  • hsuhsu Registered User regular
    As you have experienced, you are far better off going with a software raid option, whenever possible. Both Windows 7/8 and Linux offer software raid, out of the box.

    Software OS type raid only requires compatible software when a problem occurs, which is a much simpler problem to solve.

    iTNdmYl.png
  • Apothe0sisApothe0sis Have you ever questioned the nature of your reality? Registered User regular
    hsu, that;s a little more difficult in the case of a VMWare ESX server.

    Tide goes in. Tide goes out.
    Es-annon NEVA 4GET
  • Apothe0sisApothe0sis Have you ever questioned the nature of your reality? Registered User regular
    Le_Goat wrote: »
    Sorry for being a bit off topic, but what does that mean: "he's totally pants"? I've never heard that before.

    Something which is "pants" is something which is not very good.

    Something totally pants, is something utterly useless!

    Tide goes in. Tide goes out.
    Es-annon NEVA 4GET
  • QuantuxQuantux Registered User regular
    Hardware RAID controllers take the load off the CPU freeing it for other things. Another benefit is cache memory; we have systems that almost grind to a halt without it (you'd think Dell and HP could supply a cache battery that lasts more than 2 months). In a personal system this impact is negligible, but on a virtual host running several windows guests that all want CPU time and disks to thrash...

    PSN/Steam - Quantux

    Apothe0sis
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