Re: Writing disk problem (WD)

[Atle Kristensen <afk@tiscali.no>]

On Tue, 16 Sep 2003 16:33:47 +0200 (CEST)
kaido@oldany.cz wrote:

>    I don't know why, but if I want write to some directory, on specific
> partition, talking about rwd0h (mount point /home), writing is OK (it
> means fast), but to some directories it's bad (very, very slowly).
>     The BSD partition is about 30GB, but as far as I know, it shouldn't be
> a problem. If you wouldn't be able to tell where problem should be,
> please, give me some tips for diagnostic software for disks (Specialy
> for WD).

I've used DLG for WDC. Such stuff is just to thest if it is broken.
Noting more else. (atactl(8) shows smartstatus)

> wd0 at pciide0 channel 0 drive 0: <WDC WD400BB-75CAA0>
> wd0: 16-sector PIO, LBA, 38146MB, 16383 cyl, 16 head, 63 sec, 78125000
> sectors
> wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2

Check out the expected speed at google (PIO mode 4, Ultra-DMA mode 2)
my head is a little bit empty now...

You can add noatime to increase the performance a little bit.

tried time dd=/dev/null of=BIGFILE bs=1024 count=1000000
at several partions to test?

There is speed difference at wd0i(who begins at cylinder 0, who is fastest)
as opposed to wd0h. The slower ones are the outers. (that is why I usually has swap,and disk intensive partions in the inner part.) 
I THINK that is something in the FAQ about the performance. Check this out.

I think that your dmesg was OK about the disk. DMA is already there.

-- 
Atle Kristensen 
Live Long And Prosper
OpenBSD 3.4-beta GENERIC#135 i586 Pentium/MMX