Re: RAID for large disks
Thanks for the responses all.
I want RAID 5 but without mirroring. The data is important but not that important.
I am planning to use LVM.
If the controller creates a stripe size of 16k, do I need to do anything special with physical extends (in pvcreate or vgcreate) ?
Do I need to do anything specific when creating a LV? I plan on striping my LV to create extra spindles. Do I need to create my ext3 filesystem with any particular settings? I am looking for a optimal tuning guide with emphasis on performace versus redudancy.
On Sat, Jun 7, 2008 at 4:27 PM, Andrew M.A. Cater <email@example.com
On Sat, Jun 07, 2008 at 12:52:24PM -0400, Mag Gam wrote:You have four or five considerations.
> With the RAID array I am planning to use RAID 5 so my data is still
> protected. My confusion is going with RAID striping (picking the right
> size). Also, Does the filesystem layout need to be specific when I do
> striping? If I am using 128k stripes, should I start my filesystem on 129k
> and end with max-(128+1k)?
You mentioned you were going to use your 12 disks as two RAID arrays.
If one is going to be for your data and one for a backup of that data -
2 x RAID 5 and then RAID1 [5 x 500 = ~2.5TB mirrored].
If you need maximum data storage - all your disks in one array in RAID
11 x 500, one spare - 5.5TB but you rely on the spare :)
If you need data resilience - all your disks in one array in RAID 6 or
Hardware RAID control is lovely - but you may need battery backup on
some cards to avoid problems on delayed writes. Hardware RAID control
also ties you to one manufacturer's cards and/or recovery utilities if a
RAID fails and you have to recover data.
If you go the hardware route: take the card defaults.
Linux mdadm works well and, under some circumstances, can approach the
performance of a dedicated hardware RAID card - disks can be swapped
into any Linux box to recover the RAID.
You can then add LVM on top.