mdbox + zlib performing less than just mdbox

[Marc Roos]

 >mdbox format is a cross between mbox and sdbox.
 >
 >The idea is that it keeps up to mdbox_rotate_size sized mbox files 
 >which contain mails. Using zlib here will not help, because zlib is 
 >not applied to the full mdbox file, but individual mails within.
 >
 >Also not sure why you think that adding compression would make things
 >faster? =)
 
atop shows a saturated lvm/disk, some were telling me that enabling
compression would alleviate on the disk io's in exchange of higher cpu
utilization.

 
 >I am not fully sure how cephfs works but you might get better results
 >with sdbox format.
 >

I think the one message / one file, is bad for cephfs storage, as I 
understand ceph creates quite a bit of overhead there.
https://www.mail-archive.com/ceph-users@lists.ceph.com/msg48054.html
 
 >> On 14 January 2019 at 17:30 Marc Roos <M.Roos at f1-outsourcing.eu> 
wrote:
 >> 
 >> 
 >> 
 >> I have test environment to determine what would be best settings. I 
have 
 >> been told that enabling zlib compression would be good to save iops 
on 
 >> storage. But doing the test now, I get worse results. 
 >> 
 >> [@test2 ~]# pr -m -t mail04-mdbox-vdb-append-64kb-6.log 
 >> mail04-mdbox-vdb-append-64kb-8.log |less
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    1    1    6   1/  1                 1    1    6   1/  1
 >>    0    0    9   1/  1                 0    0    8   1/  1
 >>    0    0    7   1/  1                 0    0    8   1/  1
 >>    0    0   10   1/  1                 0    0    9   1/  1
 >>    0    0    7   1/  1                 0    0    6   1/  1
 >>    0    0    8   1/  1                 0    0    8   1/  1
 >>    0    0    9   1/  1                 0    0    8   1/  1
 >>    0    0   10   1/  1                 0    0    8   1/  1
 >>    0    0    9   1/  1                 0    0    7   1/  1
 >>    0    0   11   1/  1                 0    0    7   1/  1
 >>   29    3 1093 ms/cmd avg             43    2 1232 ms/cmd avg
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    0    0   10   1/  1                 0    0    9   1/  1
 >>    0    0    9   1/  1                 0    0    7   1/  1
 >>    0    0   10   1/  1                 0    0    7   1/  1
 >>    0    0    9   1/  1                 0    0    6   1/  1
 >>    0    0   11   1/  1                 0    0    8   1/  1
 >>    0    0    9   1/  1                 0    0    7   1/  1
 >>    0    0    8   1/  1                 0    0    6   1/  1
 >>    0    0   11   1/  1                 0    0    7   1/  1
 >>    0    0    9   1/  1                 0    0    5   1/  1
 >>    0    0    9   1/  1                 0    0    9   1/  1
 >>    0    0 1063 ms/cmd avg              0    0 1413 ms/cmd avg
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    0    0    8   1/  1                 0    0    8   1/  1
 >>    0    0   10   1/  1                 0    0    8   1/  1
 >>    0    0    7   1/  1                 0    0    8   1/  1
 >>    0    0   10   1/  1                 0    0    6   1/  1
 >>    0    0   10   1/  1                 0    0    7   1/  1
 >>    0    0   11   1/  1                 0    0    8   1/  1
 >>    0    0    7   1/  1                 0    0    8   1/  1
 >>    0    0   11   1/  1                 0    0    6   1/  1
 >>    0    0    8   1/  1                 0    0    7   1/  1
 >>    0    0   10   1/  1                 0    0    8   1/  1
 >>    0    0 1077 ms/cmd avg              0    0 1382 ms/cmd avg
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    0    0    7   1/  1                 0    0    6   1/  1
 >>    0    0    9   1/  1                 0    0    4   1/  1
 >>    0    0    6   1/  1                 0    0    7   1/  1
 >>    0    0    9   1/  1                 0    0    7   1/  1
 >>    0    0    8   1/  1                 0    0    7   1/  1
 >>    0    0   10   1/  1                 0    0    5   1/  1
 >>    0    0    9   1/  1                 0    0    8   1/  1
 >>    0    0    7   1/  1                 0    0    6   1/  1
 >>    0    0    9   1/  1                 0    0    6   1/  1
 >>    0    0    7   1/  1                 0    0    8   1/  1
 >>    0    0 1246 ms/cmd avg              0    0 1524 ms/cmd avg
 >> ...
 >> ...
 >> ...
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    0    0    8   1/  1                 0    0    5   1/  1
 >>    0    0    6   1/  1                 0    0    4   1/  1
 >>    0    0    6   1/  1                 0    0    4   1/  1
 >>    0    0    7   1/  1                 0    0    4   1/  1
 >>    0    0    5   1/  1                 0    0    5   1/  1
 >>    0    0    5   1/  1                 0    0    4   1/  1
 >>    0    0    6   1/  1                 0    0    4   1/  1
 >>    0    0    7   1/  1                 0    0    5   1/  1
 >>    0    0    6   1/  1                 0    0    4   1/  1
 >>    0    0    7   1/  1                 0    0    5   1/  1
 >>    0    0 1596 ms/cmd avg              0    0 2308 ms/cmd avg
 >> Logi Sele Appe                      Logi Sele Appe
 >> 100% 100% 100%                      100% 100% 100%
 >>    0    0    7   1/  1                 0    0    4   1/  1
 >>    0    0 1583 ms/cmd avg              0    0    4   1/  1
 >>                                        0    0 2331 ms/cmd avg
 >> Totals:
 >> Logi Sele Appe                      Totals:
 >> 100% 100% 100%                      Logi Sele Appe
 >>    1    1 1978                      100% 100% 100%
 >>                                        1    1 1145
 >> 
 >> 
 >> 
 >> 
 >> 
 >> 
 >>
 >
 >