sos on cyrusimapd

[Eric W. Bates]

We have an SSD dedicated for cache and another dedicated for the log.

They seem to help.

On 6/28/2018 4:45 PM, Albert Shih wrote:
> Le 27/06/2018 à 12:58:22-0400, Eric W. Bates a écrit
> 
> Hi,
> 
> Thanks you *very* much for your answer.
> 
> I will try that. But I'm know pretty sure that the problem doesn't come
> from network but from I/O of the disk.
> 
> I manage to configure my mutt (my old MUA) to keep the connection, he lost
> the connection because by default he keep the connection only for 15
> secondes. Changing that to 600 secondes and I never get disconnected.
> 
> But I still get some hang (10-30 sec) and I think it's the I/O because the
> server hang too or at least very slow down (when I'm connected by ssh) and
> If I use atop I'm see the disk are busy.
> 
> Another point is during those time (~1500 connections for ~500 uniques
> users), the ARC go down to 20G (by configuration it's get 96Go).
> 
> I will try the zfs tweaking.
> 
> 
>>
>> kern.ipc.maxsockbuf=4194304 # (default 2097152)
>> net.inet.tcp.sendbuf_max=4194304  # (default 2097152)
>> net.inet.tcp.recvbuf_max=4194304  # (default 2097152)
>> net.inet.tcp.mssdflt=1460  # (default 536)
>> net.inet.tcp.minmss=1300   # (default 216)
>> net.inet.tcp.cc.algorithm=htcp  # (default newreno)
>> net.inet.tcp.cc.htcp.adaptive_backoff=1 # (default 0 ; disabled)
>> net.inet.tcp.cc.htcp.rtt_scaling=1 # (default 0 ; disabled)
>> net.inet.tcp.syncache.rexmtlimit=0  # (default 3)
>> net.inet.ip.rtexpire=10      # (default 3600)
>> net.inet.tcp.syncookies=0  # (default 1)
>> net.inet.tcp.tso=0   # (default 1)
>>
>> kern.ipc.soacceptqueue=32768  # (default 128 ; same as kern.ipc.somaxconn)
>> net.inet.tcp.delayed_ack=0
>>
>> Been quite a while since we set all that up and it's been performing well.
> 
> well, from thunderbird point of vu everything seem fine, only some *normal*
> slow down, users doesn't complain.
> 
> I complain because it's big server with lot of disk (24 disks, 2 SSD for
> /var/imap, RAM 192Go), so....I like to make it very efficient
> 
> And again thanks you for your help.
> 
> Regards.
> 
> 
> 
> 
> --
> Albert SHIH
> DIO bâtiment 15
> Observatoire de Paris
> xmpp: jas at obspm.fr
> Heure local/Local time:
> Thu Jun 28 22:35:43 CEST 2018
> 

-- 
Clark 159a, MS 46
508/289-3112

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