I have an old PCI-X controller running 8 drives in RAID 5. I'd like to dump the controller and go to software RAID under Ubuntu. Is there a way to do this and retain the data from current array?

EDIT: (and a slight tangent) The answers below are certainly fine, but here's a bit of added detail in my specific situation.

The hardware raid was being done by an old Promise raid card (don't remember the model number). My whole system went down (dead mobo, most likely) and the old controller was a PCI-X card (not to be confused with PCI-e). I asked the question hoping to salvage my data. What I did was buy another Promise (HighPoint) card, and plug all the drives in and install Ubuntu. I was expecting to have to rebuild the array, but surprisingly enough, the HighPoint card saw the old array and brought it up clean.

Moral of the story - it looks like at least Promise controllers store their metadata on the arrays themselves, and appear to have some amount of forward compatibility.

  • Does you raid currently show as single disk (like sda) or as mapper-device (like nvidia/xyz4711)? Do you "see" the physical disks under Ubuntu? – Nils Aug 26 '12 at 20:53
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    Without having to copy the data to another set of disks? Probably not. If there is a way, it depends on the on-disk format of your old controller. What's the exact model of your RAID controller? – Gilles Aug 26 '12 at 21:24
  • i don't think there are any hardware raid cards (whether real raid or fake-raid) that have an on-disk format compatible with linux mdadm software raid. Some fake-raid controllers may be compatible with device-mapper raid (dmraid) - as fake-raid they're already 'software raid', just not mdadm. Backup and Restore is almost certainly the only way to convert. – cas Aug 26 '12 at 21:53
  • @nils - the box is running windows right now, and it shows up as a single drive – kolosy Aug 27 '12 at 23:05
  • @Gilles it's some old POS Promise card. – kolosy Aug 27 '12 at 23:05

If you actually have a RAID configured through hardware (i.e., the operating system sees fewer physical disks than you actually have) there's no hardware to software conversion method. You have to back up the data to an alternate location, convert the RAID manually, and restore.

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