Well, obviously it the depends on the mail amount.
We have about 1000 mailboxes with about 350GB of online mail. On spike
hours we have a full recycle of the logs in about 10 minutes especially
because of circular replication increasing the server activities.
Restart after a crash takes more or less 2 minutes.
---
Andrea Brancatelli
Schema31 S.p.a.
Responsabile IT
ROMA - BO - FI - PA
ITALY
Tel: +39. 06.98.358.472
Cell: +39 331.2488468
Fax: +39. 055.71.880.466
Società del Gruppo SC31 ITALIA
Il 2015-11-09 12:26 Jure Pečar ha scritto:
> On Mon, 09 Nov 2015 10:54:48 +0100
> Andrea Brancatelli <abrancate...@schema31.it> wrote:
>
>> My blind shot is that it doesn't depend on dbmail itself, but to MySQL
>> "filling up".
>>
>> Things probably get slow when either:
>>
>> * your controler cache gets filled and the controller starts writing
>> for real to disk
>> * your InnoDB log buffer gets full and the DB has to start committing
>> pending transactions to the real IDB files.
>>
>> There is not much you can to for the first thing, but for the second one
>> you can tweak the innodb_log_file_size and innodb_log_files_in_group.
>>
>> The purpose of those files is being written sequentially thus avoiding
>> the bottleneck of the disk having to seek the inodes and the free inodes
>> as the table grows.
>>
>> I suggest you to "watch" those file while the DB is appending the
>> messages and see how fast they get filled, a complete roundabout implies
>> a flush to the real tables.
>>
>> Just to give you a vague idea, on our system we have 6 * 512MB files.
>
> I don't think that's a smart thing to do. See
> https://www.percona.com/blog/2008/11/21/how-to-calculate-a-good-innodb-log-file-size/
> [1]
>
> We have about 2MB/min going into innodb logs and already have 2*256MB innodb
> log files, which should be plenty.
>
> What kind of append performance are you seeing on your setup?
>
> What is your crash recovery time with such large log files?
>
> Anyway IO is not the bottleneck, as our db server is capable more than 4GB/s
> (nvme is amazing). It must be something else...
Links:
------
[1]
https://www.percona.com/blog/2008/11/21/how-to-calculate-a-good-innodb-log-file-size/
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