Just an update to this issue, it's still persisting. 210meg/sec raw
reads with 100-110meg/sec throughput on filesystem reads. I'm a bit
perplexed. Setting stride and aligning sectors in my mind is to help
with write performance not read performance. So I'm left with a
couple of questions. Wha
On 24 Apr 2009 at 16:06, Konrad Rzeszutek wrote:
>
> On Fri, Apr 24, 2009 at 02:14:43PM -0400, Donald Williams wrote:
> > Have you tried increasing the disk readahead value?
> > #blockdev --setra X /dev/
> >
> > The default is 256.Use --getra to see current setting.
> >
> > Setting it to
I'm not sure if you have seen this, but there is a guide from Dell on
this subject:
http://www.support.dell.com/support/edocs/software/appora10/lin_x86_64/multlang/EELinux_storage_4_1.pdf
Also I would suggest the following changes in multipath.conf for RHEL5
device {
vendor "EQLOGIC"
Donald, thanks for the reply. This issue has me baffled. I can goof
with the read ahead all I want but it has no effect on the performance
with a filesystem. I must be missing a key buffer section that is
starving my filesystem reads.
Here is the output from iostat -k 5 during artificially gener
We are running with Async IO right now, it's yielding better results
with multipath.
On Apr 24, 5:06 pm, Konrad Rzeszutek wrote:
> On Fri, Apr 24, 2009 at 02:14:43PM -0400, Donald Williams wrote:
> > Have you tried increasing the disk readahead value?
> > #blockdev --setra X /dev/
>
> > The def
On Fri, Apr 24, 2009 at 02:14:43PM -0400, Donald Williams wrote:
> Have you tried increasing the disk readahead value?
> #blockdev --setra X /dev/
>
> The default is 256.Use --getra to see current setting.
>
> Setting it too high will probably hurt your database performance. Since
> datab
I've found that trying to reduce wire latency brings big wins in read
performance. Don't get too hung up on sequential read throughput
though--focus on parallel performance and IOPS, particularly for your
database workload.
You can fiddle with the read-ahead settings if you want, but Don's
right-
Have you tried increasing the disk readahead value?
#blockdev --setra X /dev/
The default is 256.Use --getra to see current setting.
Setting it too high will probably hurt your database performance. Since
databases tend to be random, not sequential.
Don
On Fri, Apr 24, 2009 at 11:07 AM,
As an update:
new observed behavior:
- RAW disk read performance is phenomenal (200meg/sec)
- Ext3 performance is 100meg/sec and tps in iostat aren't going about
800 (50k with raw disk).
Some added info:
- This system has an oracle database on it and it's tuned for huge
pages..etc (see sysctl po
