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Re: [webmin-l] High I/O usage issues which may be relatedto Usermin...
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From: Jamie C. <jca...@we...> - 2006-10-07 04:49:28
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On 6/Oct/2006 21:25 Jesse C. Smillie wrote .. > Currently I'm using Sendmail with the mbox format. What you say does > make sense though. Towards the end of the year I did notice our email > traffic increasing so it would be only reasonable that the old way of > doing things could cause us issues with incoming mail on the rise. > > Doing a quick search on google I noticed that doing Maildir shouldn't be > a huge problem with some minor mods to promailrc. However what I don't > understand is does that mean new mail goes into > /var/spool/mail/username/<messages here> or would it be > ~username/mail/inbox/<messages here>? Typically, the inbox for Maildir format is ~/Maildir . You can have mail delivered to this with a line in /etc/procmailrc like DEFAULT=$HOME/Maildir/ > Lastly, as far as the conversion is usermin cabable of reading two > different formats at a time? I ask because I wonder can I just convert > say all the inboxs first, wait to see what it does, and then convert all > of their personal folders. Or do I need to do both sides of the puzzle > at the same time? Yes, it can read both - you can have the inbox in Maildir format, but keep other folders in mbox format under users' ~/mail directories. - Jamie > We currently are using Dovecot for the Pop3 / Imap side of things and it > appears to be really easy to convert to the different setting. > > Thanks Jaime, bTw. > -Jesse > > > Jamie Cameron wrote: > > On 6/Oct/2006 12:06 Jesse C. Smillie wrote .. > > > >> Hello once again everyone. Since the new school year started we have > >> been noticing increasingly high I/O usage on our servers. When I run > >> the top command quite often you will see the WA status swing from really > >> low up into the 70-80 even 90% range for up to a min and then drop > >> again. I spend a little time trying to track down the problem and have > >> noticed the following: > >> > >> When I/O is really high I always see the following line in "ps aux | > >> grep D": > >> 1229 14619 0.8 0.2 37272 16520 ? D 14:43 0:00 > >> /usr/local/usermin-1.230/mailbox/delete_mail.cgi > >> > >> (Note: User ID is normally not the same one when polled) > >> > >> Sometimes I also see the index.cgi file too, but no where near as much > >> as the above. > >> > >> A coworker in our department had made mention that maybe whats happening > >> has something do with the process that usermin uses to remove mail from > >> a mailbox when its deleted. Something about compacting the box during > >> the delete instead of doing it like Thunderbird and waiting to compact > >> until space can be saved. I guess case being all the reading and > >> rewriting required to removed the dead message from the box. > >> > >> I don't recall having this problem that bad last year. On occassion > >> when almost everyone was logged in things would get a little screwy, > but > >> not like this. > >> > >> General information about our config: > >> Server: > >> Processors: Dual Opteron 242's > >> Ram: 6Gig ECC DDR > >> HDs: 1.2 TB 3ware Raid Array > >> OS: Slamd 64 10.2b (Slackware more or less) > >> Kernel: 2.6.18 > >> Usermin Version: 1.230 (This was happening in the last version too > >> however. I just upgraded two days ago to see if the problem went away) > >> > >> Unfortunately dealing with I/O problems isn't my speciality so I could > >> be barking up the wrong tree here. Any suggestions would be greatly > >> appriciated as always... > >> > > > > What format are your mailboxes in? If they are in mbox format (one file > per > > user), when Usermin deletes email it will re-write out the entire mail > > file with the removed emails taken out. As you might expect, this could > cause > > substantial disk IO on large mail files.. > > > > The solution I used was to switch to Maildir format, in which each email > is stored > > in a separate file. Deleting from this format is much quicker.. > > > > - Jamie > > > > ------------------------------------------------------------------------- > > Take Surveys. Earn Cash. 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