One large filesystem vs. several smaller 2

[MrHPUX]

We have a new Oracle database going into place that will be approx. 300GB. Our DBAs would like to put this in one large filesystem. In the past I have always broken this space up into multiple filesystems. The storage is on an HDS system so it is already presented to the server as RAID5 units.

Any suggestions or reasons I should go with one approach over another?

Thanks in advance,
Brian
<*(((>< er

 

[Chapter11]

In our environment, I try to cap filesystem sizes at 8 gigs. That is not so much an issue with the OS as it is backups: with our backup software, it's easier for us to manage several smaller backups than it is a single large backup).

Also from the point of view of backups, if I have 4 tape drives, and I have multiple filesystems, I can back up filesystems in parallel. If I have only one filesystem, it doesn't matter that I have 4 tape drives, I can only do one backup stream. This ignores the fact that I could stream multiple backups inside the single filesystem, but that introduces a layer of complexity to my backups that I prefer to avoid. That layer of complexity will exist somewhere, so I'd rather it be in the DBA's domain than mine.

 

[bi]

MrHPUX: From the point of view of database performance, I'm astonished your DBAs want everything in one huge filesystem.

You want to keep the data files separated from the index files and you want to keep the rollback segments and redo logs separated from everything, including each other. It sounds as if your DBAs only have experience with databases on NT or Linux.

To protect yourself, you might want to look at some of Oracle's docs on their web site (docs.oracle.com) and see what they say about placing datafiles.

If you dump everything into one filesystem, performance is going to be terrible and you (and your AIX server) are going to get blamed. (I've been there before.)

Also, with a database that size, they will probably have more than one datafile and more than one index file. If you have smaller filesystems, the DBAs are going to be able to separate out their &quot;hot&quot; tables so you can place them on isolated or faster disks.

Don't let the DBAs push you around! They need a good sys admin to save them from themselves! You are absolutely right about breaking up the filesystem!!

 

[mrds101]

Also if you are using filesystems and not raw devices, you can only have one jfslog per fs. As I recall the max jfslog size is 128MB therefor when the log is full IO will be reduced until the jfslog is flushed.

It is therefor more logical to have several filesystems with seperate jfslogs.

Hope this helps