On the HP Discover in June 2013 (I wrote 2014, sorry for that typo). HP has announced the HP 3PAR StoreServ 7450 All-Flash Array. To optimize the StoreServ platform for all-flash workloads, HP made some changes to the hardware of the nodes. The 7450 uses 8-core Intel Xeon CPUs instead 6-core 1.8 Ghz CPUs, the cache was doubled from 64GB to 128GB and they added some changes to the 3PAR OS: HP added additional cache flush queues to separate the flushing of cache for rotating rust and SSD devices.
Yesterday I received the following tweet:
@vMario156 Yes, this was stated in an older version of the best practice guide. 1 IO is currently best practice, not only for 3PAR.
— Patrick Terlisten @pterlisten@social.cologne (@PTerlisten) June 5, 2014 Later Craig Kilborn joined the conversation and I decided to clarify this 100 or 1 IOPS myth the next morning.
@Craig_Kilborn @vMario156 I check this tomorrow at the office. I don't know why this was changed, but it has changed from 100 to 1 IO.
One of the tasks that I finish before I present the first Virtual Volumes (VV) to hosts is to discuss the need of a custom SATP claimrule with the customer. Requirement for a custom claimrule is usually, that the active and optimized path should be switched after each IO and not after 1000 IOs. Duncan Epping wrote a nice blog post some years ago. I recommend to read it.
Some basics The Storage Array Type Plug-In (SATP) is responsable for array-specific operations, like health monitoring of physical paths, reporting of path state changes and path failover.
HP 3PAR Adaptive Optimization (AO) enables autonomic storage tiering on HP 3PAR storage arrays. With this feature the HP 3PAR storage system analyzes IO and then migrates regions of 128 MB between different storage tiers. Frequently accessed regions of volumes are moved to higher tiers, less frequently accessed regions are shifted to lower tiers. I often talk with customers about AO and I know that this feature is sometimes misunderstood and misconfigured.
