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RE: On very different journalling activity on 2 servers.


I have upgraded the 'bad' machine with the latest 'up2date' kernel, but it
is possible that GRUB is still loading the older kernel. Our sysadmin at the
dayacentre says the console shows the old kernel kernel-2.4.7-10 

This might have happened because the first kernel upgrade I did on this
machine I did manually by downloading the .rpm & installing it locally.

Now I know to use /use/sbin/up2date instead but ......

How do I tell from the machine (SSH) which kernel it is actually running?

Thanks - sorry to be so ignorant.

Nico Morrison
nico morrison micronicos com
Micronicos Limited  -  London, UK.
Tel: +44 20 8870 8849 Fax: +44 20 8870 5290

From: Stephen C. Tweedie [mailto:sct redhat com]
Sent: 05 February 2003 10:13
To: Nico Morrison
Cc: 'Andrew Morton'; ext3 users list
Subject: RE: On very different journalling activity on 2 servers.


On Wed, 2003-02-05 at 08:45, Nico Morrison wrote:

> [root ns5 nico]# /sbin/hdparm  /dev/hda
> /dev/hda:
>  using_dma    =  0 (off)

> Does this mean that dma is in fact off?


> Looks like is ON on the server that has no problems and OFF on the one
> loadsa journalling?


> What do we need to do & is it safe to turn DMA ON on a busy working public
> internet server?

You don't.  

The trouble is, the kernel usually has a reason for not being in DMA
mode.  If it can negotiate DMA, it will; but the older of your two
systems did not do so, so either that older kernel doesn't know how to
drive the IDE controller in DMA mode safely, or it has detected an error
on the IDE bus and has backed off to non-DMA mode automatically.  In
both cases, forcing DMA on manually is not recommended.

I'd suggest that you upgrade the 7.2 box to the current errata kernel,
which is the same across all the 7.* releases.  That should give you the
same updated IDE drivers as the 7.3 box has, and will hopefully get you
running DMA properly.  If it doesn't, then you're going to have to check
the logs to see why DMA isn't being negotiated.


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