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Old 01-06-2016, 02:37 PM   #1
MikeyCarter
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Question Hardware raid vs software raid, is hardware raid portable?


For years now I'd get these 4-5 bay enclosures and use them as JBOD with md. My reason...if the enclosure dies (which quite a few have died over the years)... then I can use any enclosure, even just a bunch of cables to get things up and running again.

So my question. Am I right in thinking if I have enclosure X I need exactly enclosure X to get the raid back up and running with hardware raid? or is RAID the same on all/most of these enclosures that I can just move the physical drives around?

Is there a list of similar ones which software raid can run in a pinch if needed? (eg the enclosure dies so I just start running cables to esata cards... till I can order a new one)
 
Old 01-06-2016, 03:24 PM   #2
MensaWater
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Hardware RAID if provided by the enclosure as opposed to an adapter in your server can vary by vendor.

Given that you can safely move the entire enclosure from one server to another with the RAID intact but you'd have to make sure your new server knew to use it (e.g. imports VG info if in LVM).

Moving the drives from one enclosure to another could be problematical. Some RAID such those done on Dell PERC cards (which are generally just OEMed from LSI) actually puts information about the RAID on each disk and on the controller. If you replace the controller it can learn the RAID from the disks and if you replace the disks they can learn from the controller. They even give you an option as which to do if they find a mismatch (e.g. if you still had a working controller in one server and had replaced a failed drive with a drive previously in another server's RAID).

Your question appears to be aimed at the idea of moving all disks from one enclosure to another so I'd suggest you do that via software RAID as your new system can be told to use the software RAID setup for the new paths of the disks.
 
Old 01-06-2016, 04:30 PM   #3
suicidaleggroll
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I agree with the above.

True hardware raid is portable, just move the controller card and drives over, or even move the drives over to a compatible controller card, and you're good to go. I do not believe the raid offered by your enclosures is a true hardware raid though (unless you're spending a LOT of money on these enclosures...), most likely they're what's known as "fake raid". Portability of fake raid systems can vary from vendor to vendor and are generally best avoided.

More on the differences here:
http://skrypuch.com/raid/

Last edited by suicidaleggroll; 01-06-2016 at 04:32 PM.
 
  


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