Re: Stripe sizes with gstripe

2008-06-13 Thread Wojciech Puchar
Does gstripe read an entire stripe at a time? If so, why do that instead of just reading a few requested blocks? If not, then is there any advantage to large stripes? Apparently it won't read anything larger than your stripe size which defaults to a miserable 4k. depending from what's

Re: Stripe sizes with gstripe

2008-06-13 Thread Kirk Strauser
On Thursday 12 June 2008, David Kelly wrote: Apparently it won't read anything larger than your stripe size which defaults to a miserable 4k. Ugh. It seems like there are a few possibilities here, and I'm not sure which is actually true. Say you have two drives, striped. 1) Ideally, you

Re: Stripe sizes with gstripe

2008-06-13 Thread David Kelly
On Fri, Jun 13, 2008 at 09:08:48AM +0200, Wojciech Puchar wrote: Does gstripe read an entire stripe at a time? If so, why do that instead of just reading a few requested blocks? If not, then is there any advantage to large stripes? Apparently it won't read anything larger than your

Re: Stripe sizes with gstripe

2008-06-13 Thread Kirk Strauser
On Friday 13 June 2008, David Kelly wrote: Still, I don't understand what is going on when I use md5(1) on a gigabyte file hosted on a gstripe partition with 128k stripes that systat -v reports transactions are usually between 42k and 43k each? Even more unlikely, why are *my* numbers almost

Re: Stripe sizes with gstripe

2008-06-13 Thread Kirk Strauser
On Thursday 12 June 2008, you wrote: If there is a tuning knob that I have missed, would appreciate being told what. Dang it; hit send on accident. Anyway, should the partition offsets on your gstripe volume be a multiple of the stripe size or of the filesystem's block size? -- Kirk

Re: Stripe sizes with gstripe

2008-06-13 Thread Wojciech Puchar
then single read is rarely split on 2 disks, while multiple reads have good chances to touch different drives Come to think of it I didn't try setting the stripe size larger than the ATA max transaction size of 128k. yes it is. max transaction doesn't begin on boundary. may (usually will)

Re: Stripe sizes with gstripe

2008-06-13 Thread Wojciech Puchar
Still, I don't understand what is going on when I use md5(1) on a gigabyte file hosted on a gstripe partition with 128k stripes that systat -v reports transactions are usually between 42k and 43k each? because every single 128kB reads is CROSSING 128kB boundary?

Stripe sizes with gstripe

2008-06-12 Thread Kirk Strauser
Does gstripe read an entire stripe at a time? If so, why do that instead of just reading a few requested blocks? If not, then is there any advantage to large stripes? -- Kirk Strauser signature.asc Description: This is a digitally signed message part.

Re: Stripe sizes with gstripe

2008-06-12 Thread David Kelly
On Jun 12, 2008, at 3:21 PM, Kirk Strauser wrote: Does gstripe read an entire stripe at a time? If so, why do that instead of just reading a few requested blocks? If not, then is there any advantage to large stripes? Apparently it won't read anything larger than your stripe size which