Say I start a RAID 5 array with 3 320gigglebyte drives. Down the road I wish to upgrade the 320s to 750s. It would seem that removing a 320 and then adding in one 750 drive at a time and rebuilding the array would allow for the array to 'just' increase in capacity. Is this a correct assumption? Do the controllers found on most on-board raid solutions support this?
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RAID 5 question
- Thread starter breadman
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I doubt many on board controllers would support doing this. I don't even think very many dedicated hardware controllers support or recommend doing this either. I have done it on a dedicated SCSI IBM Serveraid 5i controller with a RAID 5 set - pull a 36GB drive, plug a 73Gb and wait for it to rebuild, then do the same with the other drives. While it did work, I also spoke with IBM on this and they were very adamant that it was a very bad idea to try and expand an array in this manner. Better to plug a big external drive up - back up / copy everything to it, create the new array and copy / restore the data. I think only very high end dedicated controllers would support doing this.
This is a false assumption, you can not increase a RAID 5 capacity this way, if you integrate the 1x 750 gig into the array of 320s, it will only use/see the first 320 gigs of the drive. You can't slowly increase a RAID 5's capacity, one [H]ard disk at a time that way. Its best to do whats said above^^ and backup and start fresh with new harddrives. And only the best of the best RAID controllers allow for "on-line expansion" the term for increasing an array's capacity, and none of the on-board (on motherboard?) controllers allow for that.
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I also probably should have pointed out that I was not able to expand the array until ALL of the drives in the array had been replaced with the larger drives. Until then all the additional space on the drives was totally unusable in any way. Also - the way it worked out in that one time I did this - all I could do with the extra space when done was to either create a new partition in Windows Disk Management - or use something like Partition Magic to extend the partition. In the end I did end up backing up the data to another drive and simply recreated a whole new RAID 5 set.
The Hunter
Limp Gawd
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This is possible to do using Linux software RAID. As mentioned you need to have every disk the same size. Basically the way it works is you'd take out a 320, replace it with a 750, wait for it to rebuild, then repeat until the arrray is all 750s, then you grow the array to fill the extra space, and then expand the filesystem.
Full details in my thread here: http://www.hardforum.com/showthread.php?t=1178081
Full details in my thread here: http://www.hardforum.com/showthread.php?t=1178081
I heard with SATA cards like 3ware series, Areca etc ones that have onboard controllers are capable of doing "on-line expansion", then if you are running Windows XP Pro or Server 2003 then you can just use the command prompt and type in "Diskpart" to extend the partition to the newly added drives.
Only downside like everyone said is that it will take a long time and if something fails or you lose power, anything at all, well you just kind of toasted your RAID...
Only downside like everyone said is that it will take a long time and if something fails or you lose power, anything at all, well you just kind of toasted your RAID...
Well, heh, ill be damned. Thats a fine solution, a bit pricey, but in that form factor, its nice.
One can build something with specs that match from old, retired hardware, real easily, however it wont be as good looking, thats for sure.