Dear All, Plainly trying out the behavior of mysql showed that in my virtualized environment, InnoDB does survive unfriendly shutdowns if the files are kept on a virtual disk (qcow2 via virtio). So the problem itself seems to be associated with nfs. Nevertheless, I will try to separate the mysql server (using InnoDB) from my mailpiler server.
Thank you very much for your feedback. Being pointed at nfs as the probable cause made it easier to test in that direction. Regards, Michael -----Ursprüngliche Nachricht----- Von: Janos SUTO [mailto:[email protected]] Gesendet: Freitag, 15. Mai 2015 12:03 An: Piler User Betreff: Re: AW: InnoDB Question Hello Michael, On 2015-05-15 10:58, Prof. Dr. Michael Schefczyk wrote: > > Basically, I am looking for a smart model to run the system in a > virtualized environment. The hypervisor is KVM on Centos 7. I use the > standard caching (writeback) for the guest disk and no cache for nfs. > The nfs connection is over 10Gb/s Ethernet which is just used for > connecting two hypervisors to one NAS. The utilization of the overall > system is rather low - far away from congestion. > > Space of the mailpiler DB is not a real issue. In my case, it consumes > ca. 2 GB with automysql backup files. What I like to do, however, is > to use guest machines with small disks (i. e. less than 16 GB) which > permit a swift nightly live backup. Under those circumstances, > separating the mysql files sounded (and sounds) like a good idea to > keep the system scalable. In case I needed to revert the guest machine > to a state of a few days ago (this does not happen often), the current > database files including its backups would still be there. This does > seem to work well with clean shutdowns, but not with unfriendly > shutdowns. > > My practical experience is, that unfriendly shutdowns are no issue if, > (a) the database files are on the virtual guest disk itself (but at > the cost of not getting the advantages stated above) or (b) using > MyISAM, which I noted after converting from InnoDB to MyISAM on my > virtualmin web server (with the bad feeling that InnoDB is the storage > engine in the focus of future development). > > To resolve the issue with mailpiler, I do consider the following > options: > 1. Change caching model. > 2. Move to iSCSI. > 3. Move away from nfs by providing a second virtual disk to the guest, > containing just the database files. > 4. Convert to MyISAM storage engine. > > My feeling is to try 3) first and 4) second. Do you have > recommendations for me? I'd still recommend you to use a dedicated sql host with local disk(s). > In addition, I am considering to move the mailpiler DB to a separate > server along with my other databases. Of course this does only > centralize the issue so the basic problem still remains. Is it as > simple as changing the 'localhost' parameter in config.php and making > the database available at the new location? yes, however don't forget to fix piler.conf as well, then restart piler. Janos
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