Slow Performance

[Jade Bulante]

I have noticed that whenever a report is being runned on our HP9000 11.00, all the users complain that the system slowes down. All the users are hitting the same database on the same disk and I have a feeling that it's most probably a disk performance issue. I re-verified the bottleneck using sam and I saw the bottleneck on the disk. Is there quick fix to this? Can I modify the kernel?? Can I add even out the disk bottleneck??

[+¦+ó+±]

Hi,
If oracle database, you can check heavy IO's dbf file. In this case, you'd betther split dbf file to other disk.
Here's my some considerations.
- enlarge buffer cache size
nomally, dbc_max_pct : 20, dbc_min_pct : 5
bufpages : 0
- fs_async : 1
- VxFS mount option
- IO channel split
- disk striping
etc.

[Dan Hetzel]

Hi Jade,

It's not surprising if you have all your database files on the same physical disk.

Unfortunately, the only way to solve this issue would be to spread your database onto multiple disks, relocating datafiles, control files, redo logs... trying to distribute them evenly.

You'll need the help of your DBA to achieve this as it's nos as simple as moving the files.

Best regards,

Dan

[Michael McCauley]

You also might want to consider stripping across multiple spindles and multiple controllers if you have them available

[Dave Wherry]

It may not be just your hardware configuration. If your database is on one disk you certainly have an area for contention.
However, how efficient is the program? Is it using indexes? Sequential scans and "select * from..." absolutlely kill performance.

[CHRIS_ANORUO]

Take a look at these documents: S3100002312A, B and C. You can run the attached script at the peak periods to determine the actual cause of the bottleneck. Modify the kernel as specied on this thread including nbuf and bufpages=0, and set swapmem_on value to 1(one).
Glance will give you good insight into the problem on the ground.