Re: Questions on prealloc command

russ.brooks_at_dayzim.com (Russ Brooks) wrote in message news:<a7f817f2.0303251246.5abf1271_at_posting.google.com>...
> Hi,
> In order to compare the effects of the nodatainlog /etc/fstab
> parameter, a consultant issued the following command. Note: the
> discussion was whether it made sense to implement this parameter for
> filesystems that contained the online redo logs and the archive logs,
> not for data or indices.
>
> /bin/time -p prealloc myfile 1000000000
>
> The results indicated slightly poorer I/O performance with the
> datainlog parameter. The question is, was this a valid simulation of
> I/O for online redo logs?
>
> Thanks,
> Russ

According to Veritas File System system admin guide, a "nodatainlog mode file system is approximately 50 percent slower than a standard mode VxFS file system for synchronous writes" and is supposed to be used "on systems with disks that do not support bad block revectoring" (not sure exactly what that technology means). So you get poorer instead of better performance as expected.

BTW, what is "prealloc"? Is it like mkfile on Solaris?

Yong Huang Received on Wed Mar 26 2003 - 15:41:01 CST