file system capacity and performance

[Cray]

When will the file system capacity harm disk I/O performance? Is is good, fair, or bad if %free is less than 10%, or 5%?

[Jeeshan]

Actually it depends upon your application.

and load in the files system.

its safe to distribute the load between the file systems.

but its fare to remain the file systems as near as 85%. but this is not for I/O performance. but for safe distance of file system becomes full.

[Steven E. Protter]

Shalom,

How you use the file system will have a lot to do with it.

My /opt file system which contains binaries has operated quite nicely with 2% free. Those files don't change much, and there is not a lot of heavy I/O.

An oracle database on filesystem will have trouble operating in that environment and the database my stop when Oracle tries to cut a new extent and there is not enough space.

I generally get concerned for performance and other reasons at 10% free or less.

But as the saying goes, your mileage may vary.

SEP

[Emil Velez · Accepted solution]

with HFS over 90% it has issues finding 8K blocks contiguous.

JFS filesystems can be defragmented so files can be written contiguous therefore less pointers. For example if you have a 100MB file you could access all of the blocks of the file with 4 pointers if there si 32 MB free in allocation units within the file system.

You can use fsadm -e -d to defrag a JFS filesystem which makes files contiguous and minimizes the number of pointers a inode has for a file.

[Chauhan Amit]

Hi,

Check this doc for file system performance and tuning

http://docs.hp.com/en/5576/JFS_Tuning.pdf

Regards,
Amit