1. do you want the code ?
2. I managed to gain linear perfromance with raid5.
it seems that both raid 5 and raid 0 are caching read a head buffers.
raid 5 cached small amount of read a head while raid0 did not.
On 1/4/06, JaniD++ <djani22@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message -----
> From: "Raz Ben-Jehuda(caro)" <raziebe@xxxxxxxxx>
> To: "Mark Hahn" <hahn@xxxxxxxxxxxxxxxxxxx>
> Cc: "Linux RAID Mailing List" <linux-raid@xxxxxxxxxxxxxxx>
> Sent: Wednesday, January 04, 2006 9:14 AM
> Subject: Re: raid5 read performance
>
>
> > I guess i was not clear enough.
> >
> > i am using raid5 over 3 maxtor disks. the chunk size is 1MB.
> > i mesured the io coming from one disk alone when I READ
> > from it with 1MB buffers , and i know that it is ~32MB/s.
> >
> > I created raid0 over two disks and my throughput grown to
> > 64 MB/s.
> >
> > Doing the same thing with raid5 ended in 32 MB/s.
> >
> > I am using async io since i do not want to wait for several disks
> > when i send an IO. By sending a buffer which is striped aligned
> > i am supposed to have one to one relation between a disk and an
> > io.
> >
> > iostat show that all of the three disks work but not fully.
>
> Hello,
>
> How do you set sync/async io?
> Please, let me know! :-)
>
> Thanks,
> Janos
>
>
>
--
Raz
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