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Re: [ldap] Implementation Suggestions

Igor Brezac wrote:

On Fri, 20 Jan 2006, Spicer, Kevin wrote:

From: Daniel Henninger [mailto:daniel@ncsu.edu]
It may be worth adding the noatime flag to the filesystems that hold
data and (bdb) logs.  You are indexing a lot of attributes, do you

No atime?  That's interesting.  I've never heard of that, what does
that do?
From mount_ufs(1M)
                     By default, the file system is mounted with
                     normal  access  time  (atime) recording. If
                     noatime is specified, the file system  will
                     ignore access time updates on files, except
                     when they  coincide  with  updates  to  the
                     ctime  or  mtime.  See stat(2). This option
                     reduces disk activity on file systems where
                     access  times are unimportant (for example,
                     a Usenet news spool).

                     noatime turns  off  access  time  recording
                     regardless of dfratime or nodfratime.

                      The POSIX standard  requires  that  access
                     times  be marked on files. -noatime ignores
                     them unless the file is also modified.
I think this was introduced in Sol7 or 8,

This is still not a lot files to really make a difference.

You are better off looking at forcedirectio if it is available on solaris 8. This certainly helps with sql db performance.

I wouldn't expect the noatime option to make much difference; though using direct I/O in BerkeleyDB could help a little. It's important to remember that the BDB cache files aren't read or written like normal files, they're just serving as backing store for a mapped memory region. BDB won't actually issue reads or writes to the individual database files unless it needs to flush the BDB cache or pull something in that's not in the cache. Solaris will generally only update the atime once after the first mmap reference.

 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/