I had an issue somewhat related when doing heavy I/O and had database archive logs running. It ended up being aio issues such as having large enough values in /proc/sys/fs/aio-max-nr. I don't remember the details for sure. But I think there has been a kernel bug related to aio. But I would see the same behavior with cpu load low but vmstat showing high I/O on disk. I could even see aio errors in the alert_log.
Without making any changes to /proc the 2.6.21 kernel fixed my problems with this. But if you're running supported SLES this probably isn't an option for you.
Warren
-----Original Message-----
From: Michael Taylor [mailto:mdtaylor69@(protected)]
Sent: Wed 5/9/2007 1:24 PM
To: Arun Singh; suse-oracle@(protected)
Subject: Re: [suse-oracle] Heavy I/O causes servers to become unusable
Usually issues like that can be resolved by applying the latest firmware for all affected systems, (server, storage, etc) and the latest SLES Service Pack and online updates.
I was able to get a 32 GB DL 585 quad socket dual core up to a load average of 125 applying large ERP upgrades on SLES-9 when those machines first came out. After a few firmware updates and SLES online updates, it was 5 to 10 times faster than similarly sized Sun boxes.
-Michael
Arun Singh <Arun.Singh@(protected)
Is server swapping under heavy load? Please post brief output of vmstat, iostat and top under I/O load.
-Arun
>>> On 5/9/2007 at 11:58 AM, wrote:
> We have Oracle databases and applications running on IBM servers -- SLES8
> on our apps server and SLES9 on our db servers.
>
> We have our development servers setup with RAID 5.
>
> We find that when I perform heavy I/O such as copying a database or
> applying patches or upgrades, the servers become unusable. TOP will show
> CPU idle of 35 - 50 % but a load average or 10 - 15. This happens on
> internal disks as well as disks on our EMC Clarion so we suspect it is more
> of a server or OS issue.
>
> I have been a dba for 12 years and have performed the same operations on HP
> and Sun Solaris. On Sun and HP, I would see the server become slow, but not
> unusable.
>
> Does anyone have any suggestions?
>
> Angie
>
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