Linux SW raid..

MasterPlan1 · 30 Dec 2010 at 13:05

Quick one, like HW raid, do all disks need to be the same brand\model? Or can they be a mishmash of different disks? My one worry is that my old 1Tb WD Green has significantly lower cache than the newer ones.

zetec452 · 30 Dec 2010 at 14:05

It would help the consistency of the array if all disks are the same. If you want this for redundancy you could consider using JBOD and something like rsnapshot to copy the data across.

KIA · 30 Dec 2010 at 18:13

I think you'll be fine.

memyselfandi · 30 Dec 2010 at 21:29

If the drives are the same capacity then they should be fine.

BigglesPiP · 31 Dec 2010 at 01:01

Linux sw raid works on partitions, not block devices. Any two or more same sized partitions will suffice, even 2 on the same disk so be careful.

As for performance, it'll be better, but not as better as homogeneous drives. Just keep the stripes big, 256 or 512k.

memyselfandi · 31 Dec 2010 at 09:03

BigglesPiP said:
Linux sw raid works on partitions, not block devices. Any two or more same sized partitions will suffice, even 2 on the same disk so be careful.

As for performance, it'll be better, but not as better as homogeneous drives. Just keep the stripes big, 256 or 512k.

True ... Although I wouldn't go with multiple raid partitions in the same array on the same physical disks .... I tried it once (for a laugh to see if it would let you do it) and whilst it worked for a while it did go dramatically pear-shaped under the slightest load

(on top of the obvious reasons why not to do it)

matja · 31 Dec 2010 at 23:24

I've used linux md raid5 on 2 IDE disks and 2 SATA disks, all different models, in the same array for about 4 years - no probs, it's exactly what it's designed to handle