MSA1000 A/A performance worse than A/S (VMS BACKUP)

[Tim Hughes_3]

Hi all. After upgrading our MSA1000s from A/S (4.48) to A/A (7.0) we have noticed a significant performance decrease when doing backups. Other I/O seems about the same or better.

VMS BACKUP bypasses the VMS file cache so it has a greater reliance on the controller cache than normal I/O.

I suspect that going to A/A reduced the amount of READ and READ AHEAD cache available for an individual LUN. I assume in A/A all the cache is shared which means each controller only gets to use half of it. The other half is hidden. The total amount cache available is the same but per LUN it is reduced. Is the correct?

Anyone seen VMS backup performance drop off with A/A? Any work-arounds? Can I configure 7.0 as A/S?

Tim