SUMMARY: RAID interleave for Solaris Volume Manager

From: Anshuman Kanwar (anshuman@expertcity.com)
Date: Mon Jun 30 2003 - 12:41:25 EDT


Many thanks to Kevin Buterbaugh for an excellent reply and book rec.

> The "-i" option to metainit is the amount of data that
> is going to be written per disk before moving to the next
> disk in the stripe. Therefore, in your RAID 0+1 example,
> an interlace of 16K with give a 80K chunk. For
> a 10 disk RAID 5, a 16K interlace gives a 144K chunk.

> What's really important is matching up the interlace given to
> metainit with the maxcontig parameter passed to the newfs
> command when creating a UFS filesystem. The maxcontig should
> be some integer multiple of the chunk size. So, for example,
> with your RAID 0+1 stripe, you'd want a maxcontig of 80 or 160
> or 240 or ... K. HTH
>
> If you don't have it, I'd recommend picking up a copy of "System
> Performance Tuning" (2nd edition) by Musumeci / Loukides, published
> by O'Reilly. It's got a more detailed explanation of what I've
> tried to summarize above. HTH...

Along with this I am using the forcedirectio and noatime flags. Performance
has increased about 2.5 times.

 

Thanks again for being a great resource.
-ansh

P.S. I'm sorry if I offended the charter of the list by asking a simple
question. Hichael Morton [mh1272@yahoo.com] seems to have been particularly
irked. Anyway, I think this was an operational question and the
documentation was obscure.

> ==================================
>
> Kevin Buterbaugh - Systems Engineer
> LifeWay - www.lifeway.com

 
> sunmanagers-bounces@sunmanagers.org wrote on 06/30/2003 12:51:11 AM:
>
> > Hi managers,
> >
> > I have a basic question regarding -i flag for metainit.
> > What does this interlace size mean in terms of actual disk
> > writes ?
> >
> > Suppose I have an application that writes in 64KB chunks. I
> > want Solaris Volume manager (on solaris 9) to match this:
> > I am trying to dodge multiple writes per application write
> >
> > 1) For a RAID 0+1 volume composed of 5+5 disks -i 16k will
> > give a __kb chunk ?
> > 2) For a RAID 5 volume of 10 disks how is this stripe size
> > related to interlace ?
> >
> > What should I read to grasp this relationship ? Basically I
> > am trying to extract as much performance from a A5200 as
> > possible.
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