Hej Sergio, don't know if it is still relevant but will try to give an answer anyhow.
There wasn't a limitation to the pools itself to the given number 5 or 7 (as it is 1024 as Maik already said) but there was/is a cache partitioning to avoid a full cache situation, if there are any slow draining arrays in the pool (like NL-SAS or such) using all the cache. This partitioning is/was not symmetric in a case that 2 pools may use 50% and 4 may use 25% by pool. Therefore if you have a large amount of pools with slow backend, still all slow pools could remove cache from others, and therefore affect them in caching and performance.
But I believe if this is still available in the code then it get irrelevant for "normal" installations, since the cache grew up and also the speed of the backend storage increased (are there still many NL-SAS behind SVCs?). Other improvements to the cache workflow also removed the urgency to this behavior.
Hope this helps.
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Björn Steiner
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Original Message:
Sent: Wed December 20, 2023 08:55 AM
From: Sergio Pardos
Subject: SVC: Does the limit of 7 mdisk groups best practice still stand?
Good evening
Back in the day, there was a best practice in place which stated that more than five mdiskgrps in a given SVC cluster led to excessive cache partitioning and therefore, performance degradation. That number was raised to seven on DH8 or SV1 hardware. ¿does that BP still stand on SV2 and SV3 hardware? in case it does... ¿same limit?
Thanks and best regards.
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Sergio Pardos
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