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Without OCE, you'd need to nuke the array, recreate it with the added disk and restore data from backups.aye29 said:So without online capacity exapnsion I would still be able add a drive to an existing array but I would have to rebuild each time? In either case would I have to wipe the data in the existing array to add a drive?
aye29 said:How reliable is online capacity expansion? Is it likely that using it would destroy that data on my existing array? I got a LSI Megaraid 150-6 off ebay and I want to create a 3 drive raid5 array and add more disks later using OCE. If OCE is dangerous then I'll probably just buy 6 drives and create a 6 drive array and not deal with OCE in the future.
Madwand said:It's another uptime preservation tool. Usually it won't save you any time overall -- the re-build plus partition expansion time can take more absolute time than a full restoration from backup. There are multiple potential points of failure, so it isn't a good idea to use OCE to avoid making a backup. Usually you'll get lucky, but the one time you get unlucky, it could cost you all your data.
Dew said:An advantage of XFS here is that expanding to fill the new space takes around two seconds.
Even if you use a tool like EVMS, delete+recreate is probably what'll happen underneath. As long as it starts at the same cylinder, there should be no problems. My suggestion is try making a 3-disk array, expand it to 4, and write down what steps you have to take to get it all expanded.crewd said:I have no personal experience of how exactly the OCE works but I've come to understand that it only expands the physical volume or "free space" of what the OS sees and leaves any partitions and filesystems untouched. It seems easy to enlarge an XFS with xfs_grow but don't you have to expand the underlying partition first? And how do you do that, just delete+recreate a new, larger, one with fdisk? Is this really reliable? Or could you use something like LVM or EVMS to do the job?
Possible? Sure! But I don't think the manufacturers would get very far with this approach... try it first, but my guess is it's actually a useful featurecrewd said:Is it possible when OCE'ing the array that the free space would appear "in front" of the existing partition and not "behind" it? Stupid question, maybe, but just wondering...
Heh, yeah.unhappy_mage said:Possible? Sure! But I don't think the manufacturers would get very far with this approach... try it first, but my guess is it's actually a useful feature