topic Re: Enable Asynchronous I/O (fs_async = 1) in Operating System - HP-UX

Enable Asynchronous I/O (fs_async = 1)

EML — Sat, 15 Feb 2003 16:44:23 GMT

I am thinking of trying this recommendation from HP to improve disk I/O performance. But I have some questions, if someone could help me?

I am using Informix DB. Does setting fs_sync=1 affect this DB(meaning improve perf.) even if it is using raw filesystems?

Re: Enable Asynchronous I/O (fs_async = 1)

Sridhar Bhaskarla — Sat, 15 Feb 2003 18:41:58 GMT

Hi,

fs_async parameter is effective only for file systems. The definition it is

//fs_async specifies whether or not asychronous writing of file
system data structures to disk is allowed. If no value for
fs_async is specified, synchronous writes are used//

http://docs.hp.com/hpux/onlinedocs/939/KCParms/KCparam.FSasync.html

You are using raw devices (not filesystems).

It is not recommended unless you can afford to dataloss during a system crash.

If you are planning to go for filesystems, then the OnlineJFS options mincache=direct, convosync=direct are worth considering along with delaylog.

-Sri

Re: Enable Asynchronous I/O (fs_async = 1)

Rammig Claus — Mon, 17 Feb 2003 00:08:27 GMT

Hi, the fs_async parameter affects only HFS-Filesystem and not raw-devices or VxFS-Filesystems.

Best regard ...
Claus