Re: ide drives performance issues, maybe related with buffer cache.

[John Newbie]

> > So question is : why when i am copying file from one HD to another (for
> > simplicity from /hda to /hdb)
> > the speed fall down ? Starting from about 27-30 MB/s (drives are in 
> UDMA-4,
> > hdparm -X68) it drops
> > down to 11-12 MB/s after 4-5s. In *indows transfer rate is almost 
> constant
> > and about 20-22 MB/s (same hardware). Why the h#ll we suck?
> > I feel that it's due to buffer cache, because when you use sync (while
> > copying) transfer rate is so small or even 0.
> > Drives are tuned with hdparm to highest transfer rates, readahead, 
> multiple
> > sector count (hdparm
> > for details).
> > Tried different filesystems, from classic ext2/3 to modern xfs/reiserfs. 
> The
> > same results.
> > Pure kernel from kernel.org (2.4.{19,20,21}), vendors kernels - all the

> How do you copy files? cp? dd? Midnight Commander? ;)
> Does it happen with SCSI?
> --
> vda

I've used cp & Midnight Commander (mc). Also when someone uploads big file 
on server through
samba, speed sometimes fall down to zero.

Have no idea about scsi, drives are IDE.

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