[Dovecot] Users with large (4GB) inboxes crippling dovecot

[Scott Silva]

on 5-29-2009 1:42 AM Bernd Petrovitsch spake the following:
> On Thu, 2009-05-28 at 21:28 -0500, Kyle Wheeler wrote:
>> On Friday, May 29 at 09:46 AM, quoth Curtis Maloney:
>>> This is certainly one advantage dbox and maildir have -- not being 
>>> limited to the FS file size limit per folder.
>> That's not *entirely* accurate. Certainly no single message can exceed 
>> the 2GB limit even with maildir, and the other issue that begins to 
>> come up is the impact/effect of large numbers of files. Depending on 
>> the filesystem (I'm assuming ext2?), there's probably a hard limit on 
> 
> FC4 had ext3 (unless my memory is totally mistaken).
> 
>> the number of files per directory, and almost certainly there's a big 
> 
> Subdirectories, yes (because the link count in the inode is of quite
> finite size).
> But there never was TTBOMK a limit on the number of files (!=
> Directories) in ext2 (except the trivial one: The directory is as large
> as the largest file. But that applies probably to all filesystems -
> though more recent ones allow for much larger files).
> Let alone ext3.
> 
>> performance penalty for that many files. To get good performance with 
>> Maildir and really large folders, you need a filesystem that can 
>> handle large numbersof files. Ext3 has directory hashing, ReiserFS is 
> 
> Make sure you have the "dir_index" option set on that filesystem (which
> is probably set per default anyways these days. Otherwise you can change
> it on the fly with `tune2fs`).

I don't think you can do it on the fly. Any directories created before the
option was set will not have directory indexing until a fsck is done.

<quote>

 Using Directory Indexing

This feature improves file access in large directories or directories
containing many files by using hashed binary trees to store the directory
information. It's perfectly safe to use, and it provides a fairly substantial
improvement in most cases; so it's a good idea to enable it:

# tune2fs -O dir_index /dev/hdXY

This will only take effect with directories created on that filesystem after
tune2fs is run. In order to apply this to currently existing directories, we
must run the e2fsck utility to optimize and reindex the directories on the
filesystem:

# e2fsck -D -f /dev/hdXY

Note: This should work with both ext2 and ext3 filesystems. Depending on the
size of your filesystem, this could take a long time. Perhaps you should go
get some coffee...

</quote>




> The back of my head suggests that one has to recreate the directory
> after changing that option (read: `mkdir new; mv old/* new; rmdir old;
> mv new old`. Solving the "command line too long" problem is left to the
> reader;-).
> 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 258 bytes
Desc: OpenPGP digital signature
Url : http://dovecot.org/pipermail/dovecot/attachments/20090529/29f68393/attachment.bin