Originally posted by: snowyx5
Here is the scenario:
We set up some new LUNS and put them in a TrueCopy relationship.
The LUNS are Serial ATA(groan) in an AMS500 virtualised through USPs (presented as external storage via the USP)
Configuration is identical between sites (yes, really, 100%)
The TrueCopy links between our USPs are pretty wide in terms of bandwidth.
We do a paircreate with the copy pace to 15 (the highest).
We do one lun at a time.
Here is what happens:
Write pending % on the SVOL side USP ramps up immediately.
It gets to about 70% and stabilises and remains that high until TC sync completed.
Performance on the PVOL side takes a serious dive for any hosts with other TrueCopy luns presented.
It seems that the SVOL side USP cannot destage rapidly enough and there is a knock effect to the PVOL side.
So, now we only do one lun at a time and set copy pace to 1 (the lowest).
Now the cache WP climbs to 60% and remains stable while the sync occurs.
Performance remains acceptable on the PVOL USP.
Now the query - prick the brains of the Forum ... :-)
Is there any way of controlling [i]initial sync [/i] TrueCopy traffic on the arrays ?
I'd like to deprioritise it even more than the copy pace allows.
I'd like to stop it from taking over the array when I'm careless.
Am I asking for too much, should we accept these are SATA drives and just manage them accordingly ?