Cloning RAID 5 to higher capacity drives

[TerraNova]

Hi guys

I have RAID 5 (hardware RAID) with 4 hard drives (250G each), can I clone these drives to higher capacity drives (500G each) without loosing the RAID configuration, i.e. the RAID will work after cloned.

Or. It has to be exactly same HDD brand and model and capacity?

thank you for any feedback.

[Zorb]

Yeah easy. Create another array on your controller and clone as if they are two hard drives. Ex. 4x250GB AND 4x500GB as you said, but at the same time so you have two arrays, 750GB and 1500GB. Clone from one to the other then delete the first. If necessary, add another RAID controller.

Either that or buy an extra 1000GB drive and use it temporarily to copy your RAID onto that, swap out your RAID drives (don't erase them until you're sure you're safe!) for the new drives, copy the data back over from your temp drive, and then throw it in another computer as an upgrade or turn it into a paperweight or something.

Some RAID cards support RAID5 Extension so you can (if all the information will fit) copy all your stuff onto one 500GB drive, create the array with three 500GB drives, copy the information onto the array from the single drive, and then add the other later and expand the array. Just remember it will be slow until it's done doing its thing. This kind of thing is limited to very high end SATA RAID cards, with backup batteries, and most SCSI cards that are worthy of the name can do it too.

[Zorb]

Guess I took too long editing...

But... If you're thinking of cloning the drives individually and then adding them back in, it will not work as far as I can see on any card I've used. In theory it could be done within the RAID principle (byte for byte image with a little side work), and then you could just extend your volume with a partition editor. Unfortunately, in practice, most RAID cards won't let you adjust parameters of a single array volume at such a low level, they only understand create, delete, extend, convert in most cases. Convert won't be of any use because it's used for converting from a RAID 0 or RAID 1 to a RAID 10 (or to a RAID 5 on some better cards if you add enough drives).

Now, there is an exception to this.... Many RAID cards will allow you to replace a drive on a RAID 1 or 5 with a larger drive, so if a drive dies and you can't get that small a drive, you can replace it with a larger one. This feature would be used as well to upgrade an array to larger drives. The downside to this is that it will take forever to rebuild, and your RAID will run quite slowly while it's rebuilding. If your RAID card is smart enough, it will allow you to increase the size of an array volume as long as there is enough space left on the array to handle it. In this case, you would, as in the above example, use a partition editor to then extend your partition on the array volume.

My RAID card on my big machine allowed an conversion from four 36GB IBM Ultrastar UL36LZX to four 73.4GB Quantum Atlas 10K II, then from there adding 12 more Quantums to make 16 total. It took a four days of swapping a drive every night when I left the office and telling it to rebuild, then adding the other 12 (across four channels BTW) and telling it to expand the RAID, then a day to extend the volume after all that was done.

Just remember, there's a big difference between a $3000 6 channel 512MB Ultra160 SCSI PCI-X card (hey, it was 2001), and a little $25 SIL3114R5 SATA job.

[hddguy]

Why not image to the higher disks and then cut max LBA to match original capacity?

[Cleanroom]

I agree with zorb on that it would be safer to just copy the data off to a Drive that can support all the data on the current raid. Then confirm the copy is good, then swap out the raid disk with the larger ones. Set up the new raid and then copy the data back

[Zorb]

Why not image to the higher disks and then cut max LBA to match original capacity?

When you set the max lba back to the drives' native capacity, the RAID card will probably go crazy and the array may delete itself or rebuild incorrectly. Some cheap RAIS cards will zero the first several megabytes of a new array, so if you were to respecify it if deleted, you would be in some trouble.