Mark Zealey a écrit :
Thanks; these look interesting. We have a similar nas setup but we have 2 frontend dovecot servers connecting to it and store the indexes over nfs. Could you please tell me how have you done this configuration ? 2 frontend dovecot proxy with 10 dovecot mda ? We are looking for such a configuration : 2 mda frontend with maybe an active and a passive one !
We also have around 10 mail servers running deliver to try to keep the indexes on the nfs store up-to-date. Have you done any tests with the speed of multiple boxes each maintaining a local index of the mailbox? No sorry
I suspect in this case keeping indexes on nfs would be the best bet but I don't have anything to substantiate that claim...
Also one thing to note with storing things on nfs is that there are a large number of broken kernels out there (they issue about 10* more nfs lookup requests than they should) - centos 5.1 had these issues iirc (though the centosplus kernel and centos 5.2 did fix it). Good thing to know, I'll try to change kernel before my migration !
Always give it a good test before you change the kernel on your server... I assume you are using nfs3; has anyone tried using heavily loaded nfs4 and seeing if any better performance can be achieved?
Another thing - I found that dovecot's pop3 implimentation is worse than courier's over nfs (wait state on our boxes is significantly increased). I still don't really understand why this is; I suspect it's probably due to to the indexes being created/updated though I thought these were meant to be discontinued after a while if it is just a simple login/fetch all operation. I only mention this because if you are offering pop then you should really do the same benchmarks for that.
Mark