I had naively assumed that I should install Ubuntu to a RAID 5 array to give our in house dev server the best chance of having 100% up time. I have since learned that RAID 5 might be a bad choice for Dev (due to the cost of writes) and that putting the OS and filesystem on the same RAID is not necessarily a good idea (I thought it was a necessity and if the OS was lost, so was the array).

We have 3 1TB drives. Would it be smartest to partition 100 gig of each for the boot sector, RAID1 two of those together (so the OS is RAID'd), then RAID 5 the remaining 900 Gigs per drive into a RAID 5 (effective storage of 1.8TB)? Or is a RAID 5 setup such a bad idea that I should just RAID1 two of the 1TB drives together (effective storage: 1TB) and sit on the third drive?

We are looking to run virtualization on the server (its got 4 gigs of ram and a core duo 2.93 Ghz processor, am I in trouble there?).

Thanks for any ideas or links.


Software RAID-5 is not the best choice for your bootable system drive, as it requires quite a bit of technical knowledge when it goes wrong.

That said, RAID-1 is actively supported by mdraid for your boot partition.

If you're going to run virtualization, in general disk I/O is the main bottleneck. (We run some VMs from RAID-5, but not on consumer hardware :)

I strongly advise you to invest in at least a separate mirror - or better, raid-10 - for the virtual I/O.

The OS can go on a single small mirror, and if you know the OS won't be hit hard itself this can be on shared physical drives.

But with such a small setup, and only 3 disks, no, you never want to run RAID-5.

  • Thanks for the input. When you say the OS can go on shared physical drives, you mean it can go on an array that is made up of the saem drives as the main array? Thanks – Tyler DeWitt Oct 25 '11 at 14:41
  • Yes; I used to have an old fileserver set up this way: 4GB on two drives (sda1 and sdb1) as /, 4GB on two drives (sdc1 and sdd1) as swap, and the rest of all four drives (sda2 thru sdd2) as RAID-5 storage – adaptr Oct 25 '11 at 14:55

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