[Dovecot] Indexes.
Henrique Fernandes
sf.rique at gmail.com
Thu Dec 2 16:41:05 EET 2010
Did you see the IO wait in the picture i send ?
We did not use GFS cause we need an fencing hardware, they don't garante
data without an fencing harware...
Anyway, we change to storage so we now are able to give a biger quota.
Before use to be 200 mb and pretty much alluser uses pop.
We have 9000 users, but as i see not, only 4500 are actualy active.
Now, we are making teste with ocfs2 and ext3 we might gonna use NFS.
No, i don't have a list where i can ask! =/
Thanks for the help.
Can you see how many client you have log on at same time in you system ?
[]'sf.rique
On Thu, Dec 2, 2010 at 12:09 PM, Robert Schetterer <robert at schetterer.org>wrote:
> Am 02.12.2010 14:53, schrieb Henrique Fernandes:
> > I have abou 9000 clients.
>
> many clients
> >
> > 500 GB of storage used
>
> small store
>
> anyway you shouldnt run into problems with that
> >
> > About the mail option at ocfs2 store creating, i guess the other guy
> > that format the storage system did not use.
>
> what a pitty , mail option help with small files performance like
> indexes and mail etc as far i remember
> >
> > We are looking into ocfs2 1.6 that was out few months ago. But we are
> > not able to get it running on or Centos5.5 yet.
>
> hm centos is more redhat style
> i speculate Red Hat GFS would have been the better choice
> is there a list at centos/redhat/ocfs you might can asked about bugs
> with your ocfs2/distro combination ?
>
> >
> > Are you talking abvout this optimizations?
> >
> > Dovecot supports reading a few fields from the <base filename>:
> >
> > *
> >
> > ,S=<size>: <size> contains the file size. Getting the size
> > from the filename avoids doing a stat(), which may improve the
> > performance. This is especially useful with Maildir++ quota
> > <http://wiki.dovecot.org/Quota/Maildir>.
> >
> > *
> >
> > ,W=<vsize>: <vsize> contains the file's RFC822.SIZE, ie. the
> > file size with linefeeds being CR+LF characters. If the
> > message was stored with CR+LF linefeeds, <size> and <vsize>
> > are the same. Setting this may give a small speedup because
> > now Dovecot doesn't need to calculate the size itself.
> >
> > A maildir filename with those fields would look something like:
> > 1035478339.27041_118.foo.org
> > <http://1035478339.27041_118.foo.org>,S=1000,W=1030:2,S
>
> as far i remember keep close to nfs recommands
>
> http://wiki2.dovecot.org/NFS
>
> FS caching problems
>
> NFS caching is a big problem when multiple computers are accessing the
> same mailbox simultaneously. The best fix for this is to prevent it from
> happening. Configure your setup so that a user always gets redirected to
> the same server (unless it's down). This also means that mail deliveries
> must be done by the same server, or alternatively it shouldn't update
> index files.
>
> Dovecot flushes NFS caches when needed if you set mail_nfs_storage=yes,
> but unfortunately this doesn't work 100%, so you can get random errors.
>
> Disabling NFS attribute cache helps a lot in getting rid of caching
> related errors, but this makes the performance MUCH worse and increases
> the load on NFS server. This can usually be done by giving actimeo=0 or
> noac mount option.
>
> Index files
>
> As described above, it's better to redirect users to the same server
> whenever possible. If you do this, it might also be a good idea to keep
> index files stored locally in that server. If user gets occasionally
> redirected to another server, the indexes will then be created locally
> there. This isn't a problem. However you might want to create a cronjob
> to delete old index directories.
>
> If you choose to keep the index files stored in NFS, you'll need to set
> mmap_disable=yes. Both the mmap_disable and indexing to NFS will result
> in a notable performance hit. If you're not running lockd you'll have to
> set lock_method=dotlock, but this degrades performance. Note that many
> NFS installations have problems with lockd. If you're beginning to get
> all kinds of locking related errors, try if the problems go away with
> dotlocking.
>
> -------------
>
> but i agree, there should be more info with cluster file systems in the
> wiki
>
> perhaps Timo has time to send recommands by mail, i am not sure that
> mine are optimal ( whatever i have no problems yet )
>
> >
> >
> > I will try send an image on the load of machine.
> >
> >
> > []'sf.rique
> >
> >
> > On Thu, Dec 2, 2010 at 11:25 AM, Robert Schetterer
> > <robert at schetterer.org <mailto:robert at schetterer.org>> wrote:
> >
> > Am 02.12.2010 14:10, schrieb Henrique Fernandes:
> > > With recomendation settings do you have ?
> >
> > http://wiki2.dovecot.org/MailLocation/SharedDisk
> >
> > and a few more optimizes about maildir
> > >
> > > how many clients ?
> >
> > i started the server not long ago so they are less yet ( about 100
> > maildirs )
> > but i have my own account in it which has massive mails ( 10 GB store
> > with over 1000 mails daily in out , and perhaps 10000 mails in store)
> >
> > >
> > > sorry, i did not say i use dovecot 2.0.6
> >
> > looks fine, update to 2.0.8 if ready
> >
> >
> > did you use the mail option at ocfs2 store creation ?
> >
> > what os/distro do you use , i remember bugs with ocfs with some
> distro
> > versions
> >
> > >
> > > []'sf.rique
> > >
> > >
> > > On Thu, Dec 2, 2010 at 10:40 AM, Robert Schetterer
> > > <robert at schetterer.org <mailto:robert at schetterer.org>
> > <mailto:robert at schetterer.org <mailto:robert at schetterer.org>>>
> wrote:
> > >
> > > Am 02.12.2010 13:13, schrieb Henrique Fernandes:
> > > > Hello people!
> > > >
> > > > I have huge problems with IO wait becase dovecot configured
> > to use
> > > maildir
> > > > is under OCFS2 1.4. Now i have an question to OCFS2 each
> disk
> > > action is
> > > > really heavy becaue it has no index.
> > > >
> > > > Now i am thinking in what can be done to heltp my system to
> use
> > > less disk.
> > > >
> > > > Looking for index and etc in dovecot i found this, this
> > disables
> > > the index
> > > > file on disk and leave it on ram or it disable the index
> files ?
> > > >
> > > > If you really want to, you can also disable the index files
> > > completely by
> > > > appending :INDEX=MEMORY
> > > >
> > > >
> > > > I am only trying to get dovecot to work faster. Right now we
> > have
> > > to waing
> > > > some seconds to dovecot list all emails or read an email.
> > > >
> > > > I am also thinking in right index to an NFS but i don't know
> if
> > > this makes
> > > > any diferences in performance.
> > > >
> > > > Thanks to all!
> > > >
> > > > I use 3 servres wrinting on OCFS2 one is mailman, and other
> two
> > > are to
> > > > email, I have ipvs to load balance the conections.
> > > >
> > > >
> > > > []'sf.rique
> > > >
> > >
> > > hm , i have no problems with ocfs2 (1.4.3-1: amd64 ) on drbd
> > ubuntu
> > > lucid
> > > using dovecot vers 2 recommended settings for cluster file
> systems
> > > i have my index files in the maildir dir
> > >
> > > --
> > > Best Regards
> > >
> > > MfG Robert Schetterer
> > >
> > > Germany/Munich/Bavaria
> > >
> > >
> >
> >
> > --
> > Best Regards
> >
> > MfG Robert Schetterer
> >
> > Germany/Munich/Bavaria
> >
> >
>
>
> --
> Best Regards
>
> MfG Robert Schetterer
>
> Germany/Munich/Bavaria
>
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