practical limits of files system

[Tim Killinger]

In UX 11.0 - Is there a practical limit on the number of directories that can exist within a directory?? i.e.
/dir/dir2 ....dir2 might contain 1100 directories. should we work to break this down for practical reasons relating to file system performance???

[Pete Randall]

Tim,

Usually the question is how many files, but I think how many subdirs would be pretty much the same idea. Have a look at these threads:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xb35e35a43b46d71190080090279cd0f9,00.html
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x14a293e260b0d611abdb0090277a778c,00.html
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x14a293e260b0d611abdb0090277a778c,00.html
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xe87a42308663d611abdb0090277a778c,00.html


Pete

[Steven E. Protter]

If there are too many directories, system performance will be degraded, especially if you use nfs or cifs/9000/samba to share the directories.

You can measure these issues by running the attached performance data collection script while at the same time running normal access from your application or however you do it.

1100 directies can be created, though the performance impact depends on a lot of factors.

Script is production, easy to understand, runs in the background and the data collection time period can be modified.

Its not terribly well documented, HP gave it to me.

SEP

[Michael Steele_2]

Inodes link files and directories, can be measured with sar and won't have a hard limit by file system. Inodes are a system wide parameter, ninode, measured with:

sar -v 5 5

Also refer to ulimit and the maxdsiz kernel parameters which will limit processes and users, or, disk quotas via edquota.

[Bill Hassell]

Massive numbers of subdirectories can be slower to search but will have no effect once the inode has been cached. So, it would be slow to locate the path (a flat collection of directories at a single level is faster than long subdirectory chains) but once the file(s) are open, there is little effect on read/write performance.

That being said, 1100 directories is not a lot and other than the obvious issues with doing an ls or ll, it shouldn't be too bad. However, a 3-4 level hierarchy would much easier to manage.

[Gary Yu]

there's a kernel parameter "vx_maxlink" which set the max number of subdiretories.

[Uday_S_Ankolekar]

Hope this doc helps...

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062908465

-USA..