768kb wrote:
We will use VMFS6 for our next installation too, but I do not expect any big impact to the whole system because unmap is like sending zeroes to 3PAR, which should be handled directly by the ASIC and not written down to disk.
Or is this a wrong assumption? Does 3PAR have to write zeroes to delete dirty chunklets after "unmapping" them?
Is there anyone else with more knowledge about this here?
The result should be the same, but the process is a little different between sending zeroes and sending SCSI UNMAP commands.
The UNMAP command is a SCSI OpCode (42h) so it does not need to be processed by the ASIC and sending the UNMAP command to the system should be a lot faster than sending zeroes as you are offloading the zeroing/block unmapping to the 3PAR system in the same way that other VAAI commands work.
If you want a deepdive into the UNMAP command you can read the SCSI Commands reference manual:
https://www.seagate.com/files/staticfil ... 93068h.pdf