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1 LonnyNiederstadt commented Permalink

Hello! I'm hoping to learn the maximum LUN queue depth for the Stowize v7000 when connected to an IBM Power AIX host system. <br /> In the Redbooks I see the limit of 10000 outstanding IO/s per node (lowered to 7000 for safety in queue depth calculations), but I haven't seen a maximum allowed queue depth. <br /> ESS, DS5000, and DS8000 series storage are documented as allowing host queue depth up to 256. I've seen examples of v7000 LUNs set to queue depth 80 and even 128, but no mention of a max yet. <br /> Knowing the max allowed queue depth can be critical for Oracle database implementations, to make sure that parallel query execution doesn't overflow the queue depth and start accumulating wait queue time. <br /> Thanks!

2 LonnyNiederstadt commented Permalink

Heard from Barry Whyte: other than system limits, v7000 doesn't limit the maximum LUN queue depth - although its rare to need a queue depth greater than 64. Sometimes when intervening in a hotspot that is generating LUN queue full conditions, I recommend increasing queue depth until another rebalancing/distribution action can be taken. Think I'll use 256 as a practical planned limit for that type of bandaid, so that the plans look pretty much like they would if taking the same action on a host using ds8000 series storage.