Re: Disk I/O Question - Mailing list pgsql-general
På tirsdag 10. november 2015 kl. 17:23:15, skrev teeeebro <terryb@esi.net>:
The third party application is locked down and we do not have root access to
the server. We have reached out to them for the version number of
PostgreSQL.
The application server is a virtual machine (RedHat 6) running on VMware
5.5. This is a stand-alone host server running only the third party
application. This application is used to monitor just over 5000 network
devices (routers, switches, firewalls, servers, etc.). It receives a LOT of
information and writes it to disk.
The host server has 2 local 15k drives mirrored. The host server is also
attached to the SAN via 8GB fiber channel.
For testing we did a base installation of Centos 6 and ran a command line
test provided by the application vendor.
*rm -f /tmp/foo && sync && dd if=/dev/zero of=/tmp/foo bs=4k count=12k
oflag=dsync*
They said we should be see between 7 and 10 MB/Sec.
Writing to the SAN we get around 1.7 MB/Sec.
Writing to the local drives we get around 11.3 MB/Sec.
Just a note: We have a 4 host server cluster of VMware servers running off
the SAN. There are multiple MSSQL servers running in this cluster as well
as web servers, etc. etc. About 45 servers in all. We have zero
performance issues with any of these.
Thoughts?
Thanks again!!
Terry
We used to host our solution on VMWare. We started to experience severe performance-issues which turned out to be when we hit the SAN's 8GB disk-cache.
We got ~1|MB/Sec, which is bad.
The command we used to test was:
iozone -r 8 -i 0 -i 2 -s 10000000
PG reads/writes using 8K-pages and it's important to test on >8GB, hence "-s 10000000"
-- 
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
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