El 27 nov. 2017 15:24, "Don Seiler" escribió:
Good afternoon.
We run Postgres (currently 9.2, upgrading to 9.6 shortly) in VMWare ESX
machines. We currently have effective_io_concurrency set to the default of
1. I'm told that the data volume is a RAID 6 with 14 data drives and 2
parity drives. I know that RAID10 is recommended, just working with what
I've inherited for now (storage is high-end HP 3Par and HP recommended RAID
6 for best performance).
Anyway, I'm wondering if, in a virtualized environment with a VM datastore,
it makes sense to set effective_io_concurrency closer to the number of data
drives?
I'd also be interested in hearing how others have configured their
PostgreSQL instances for VMs (if there's anything special to think about).
If the storage was exclusively for the Postgres box I'd try
effective_io_concurrency somewhere between 8 and 12. Since it is probably
not, it will depend on the load the other VMs exert on the storage.
Assuming the storage isnt already stressed and you need the extra IOPS, you
could test values between 4 and 8. You can of course be a lousy team player
and have PG paralelize as much as it can, but this eventually will piss
off the storage or vmware manager, which is never good as they can limit
your IO throughput at the virtualization or storage layers.
Cheers.
