Re: pg_dump/pg_restore --jobs practical limit?

On 11/1/23 15:42, Laurenz Albe wrote:
> On Wed, 2023-11-01 at 13:09 -0500, Ron wrote:
>> I will "soon" migrate some 1+ TB database from Pg 9.6.24 on RHEL 6 VMs to Pg
>> 14.latest on RHEL 8 VMs.  The VMs have 10Gbps "NICs", SAN-based LUNs managed
>> by LVM, and are all on ESX blades.  nproc count on some is 16 and on others
>> is 32.
>>
>> Does anyone have experience as to the point of diminishing returns?
>>
>> IOW, can I crank them processes up to --jobs=30, will I see no gain -- or
>> even degradation -- after, for example, --jobs=24?
>>
>> This would be for both pg_dump and pg_restore (which would be run on the
>> RHEL 8 VM).
> Test, test, test. Theoretical considerations are pretty worthless,

Which is why I asked if anyone has experience.

> and it is easy to measure that.

Not necessarily. Our test systems are way too small (only good enough to
validate that the script works correctly), and there's always something
(sometimes a lot, sometime just "some") going on in production, whether it's
my customer's work, or the SAN (like snapshotting /every/ VM and then
copying the snapshots to the virtual tape device) or something else.
--
Born in Arizona, moved to Babylonia.