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Re: hd sometimes 'hangs' a few seconds



the hdparm command returns:

/dev/hda:
 Timing buffer-cache reads:   128 MB in  0.75 seconds =170.67 MB/sec
 Timing buffered disk reads:  64 MB in  4.69 seconds = 13.65 MB/sec

and yes, DMA is on... in fact unmasqirq has got value 1 as well...

besides, I doubt it's due to my harddisk, since everything went fine with 
ext2...

Sincerely

Hans Schippers

On Monday 08 October 2001 23:19, Bill Rugolsky Jr. wrote:
> On Mon, Oct 08, 2001 at 10:26:33PM +0200, SainTiss wrote:
> > hi,
> >
> > I recently changed my filesystem to ext3 (from ext2), and since then, my
> > hard disk sometimes seems to 'hang' a few seconds (in fact the whole
> > system hangs then, and only the hd LED is on), before continuing
> > normally... This happens for example (not always though) when I untar an
> > archive and try to ls in the newly created directory...
> >
> > Is there an explanation for this?
> >
> > And if so, what's the best solution?
> > (I'm running RH 7.1.94 (roswell))
>
> Are you running an up-to-date RedHat kernel (I'm thinking 2.4.7-6 or
> later)? There have been numerous VM problems that are exacerbated by
> journalling.
>
> Also, I am guessing that you are using an IDE drive.  If it is not the VM,
> then it is poor IDE disk performance.
>
> You can get an idea of raw disk speed with "hdparm -tT /dev/hda"
> (assuming the drive is hda, of course. :))
>
> Try "less /proc/ide/hda/settings" and look at the last two lines.
> Verify that your hard drive is operating in DMA mode.  If not, you will
> need to investigate why not.  If it is already in DMA mode, you might
> try running with the IRQ unmasked; this can be enabled with "hdparm -u1
> /dev/hda" and can be permanently set in /etc/sysconfig/harddisks.  It
> is turned off by default, because unmasking the IRQ can cause
> corruption with some IDE chipsets.
>
> Regards,
>
>   Bill Rugolsky





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