topic Re: tuning large filesystem in Operating System - HP-UX

tuning large filesystem

Dimitry Snezhkov — Wed, 30 Oct 2002 19:51:18 GMT

I have an unusual filesystem:
it has over 7 Million small files and 5 million directories.

Processes have hard times searching through it. Backups
time out on it, trying to get datastructures in memory.
I know, there are ways to change block sizes for filesystems with many small files. Is this appropriate in this case? What else would you recommend for reorg of such filesystems ? Best practices ?

/opt/vista30 (/dev/vg130/vistafs ) :
8192 file system block size 2048 fragment size
97140736 total blocks 1686464 total free blocks
1633786 allocated free blocks 15431728 total i-nodes
421610 total free i-nodes 421610 allocated free i-nodes
1075249153 file system id vxfs file system type
0x10 flags 255 file system name length
/opt/vista30 file system specific string

thanks in advance
dimitry.

Re: tuning large filesystem

James R. Ferguson — Wed, 30 Oct 2002 20:19:48 GMT

Hi Dimitry:

Divide and conquer. Smaller is better (read, faster).

Regards!

...JRF...

Re: tuning large filesystem

A. Clay Stephenson — Wed, 30 Oct 2002 20:26:04 GMT

I doubt that any block size tuning is really going to help at all. In your case I would would divide this one filesystem into several mountpoints. I hope that you have OnlineJFS because another thing that would probably help is running fsadm -F vxfs -d -e on a regular basis to reorganize your directories and extents. I wouldn't dream of doing a reorg until you have split the filesystem.

Re: tuning large filesystem

Bill Hassell — Wed, 30 Oct 2002 20:40:16 GMT

Overall performance with millions of files and directories can only be improved with a solid-state disk. The problem is that directory searches (such as backups and processes or scripts that search for files using a mask) are done completely in the kernel aas this is filesystem management. The sizes of the files are not important, it's the sheer number of entries that must be traversed to locate a specific file.

If you think we're saying this is a bad design for datastructures, you're right! If this is a small mountpoint, say less than 2Gb, then a solidstate disk should be less than $10,000 and will give you adequate performance--assuming you have fast (500 Mhz) processors to handle the kernel code.

Otherwise, the directory structures cannot be optimized as they are scattered throughout the volume. The only fix is to use a real database rather than using a filesystem to keep track of individual items.