[Linux-PowerEdge] Linux-PowerEdge Digest, Vol 102, Issue 6
ggulik at reachmail.com
Mon Nov 5 11:02:55 CST 2012
Thanks, that's a good suggestion, but in this particular case I want
maximum size and maximum performance is not required. I do have the
rest of the slots in the MD1000 with 15k RPM SAS drives with a separate
filesystem that will be for our performance critical systems.
I'm merely trying to make sure that given the slow(er) drives in a
RAID-6 configuration I would like to ensure the performance is as good
as it should be given those trade-offs.
On 11/5/12 10:57 AM, John Lloyd wrote:
> You have a couple of trade-offs here. There was a bunch of (very good) advice about aligning stripe units and stripe widths.
> Or you could buy 4 more 2TB SATA disks, run RAID-10, keep your 12TB total, and avoid the whole striping logic analysis thing and issues with performance. RAID-10 is faster for more kinds of IO patterns than RAID-5 or RAID-6. And when a drive breaks, the volume rebuild time is only a couple of hours not a couple of days.
> The trade-offs of course are money vs performance vs effort to get the system running.
> One other hint: set the the IO readahead size. The command blockdev --setra is another good thing to do for read IO.
> Linux-PowerEdge mailing list
> Linux-PowerEdge at dell.com
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