Re: System I/O and Disk I/O

penghd wrote:

> Hi there.
>
> We have a C/S OLTP system running on oracle9i.
> When we put the oracle server on a windows 2000 Server, system works
> well. From the windows monitor tool, it show the whole system I/O is
> 8MB/s, but the harddisk R/W rate only about 500KB/s.
> But when we migrate the oracle server to an IBM pserie Server(AIX OS),
> it ran slow as hell. Because we are using Disk array, we cant get the
> real R/W rate of real harddisk, but just the I/O of the Logical
> Volume, its about 8MB/s too.
>
> So I think its some problem about the CACHE (database cache or system
> cache), is it?
>
> The PC Server and AIX Server both have 2CPU 2G MEM, and the database
> init.ora are same. Is there something need pay attention on UNIX?
>
> And should we try the Multi-Thread Server Mode? There are about 200
> client. So on the AIX Server we can see 200+ Oracle Processess.
>
> Thx, and sorry about my poor English.

Don't jump to the conclusion that it's a disk I/O problem.

Have you checked your network? Bad cables, switch and NIC configurations, and so on could be a problem for clients connecting to the new server.

Since you moved from Windows to AIX, you had to create a new database and export/import your data. Are you sure that everything, including indexes, optimizer statistics, redo logs, temporary tablespace, archivelogmode, and so on is consistent?

Break the problem down into smaller pieces, try testing a known good query locally both on the Windows box and the AIX box, directly from SQL*Plus to see if the execution time is similar. The OEM standalone tool is a quick, easy way to generate a database configuration report for comparing the old and new databases as well as memory utilization and other performance-related items.

As for Unix, tools such as "top", "iostat", "vmstat", "netstat" are less user-friendly but more powerful ways to see what's going on compared to Windows.

--Mark Bole Received on Sat Mar 06 2004 - 15:34:30 CST