HPE Storage Users Group

AO and SSD
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Author:  hdtvguy [ Mon Nov 16, 2015 6:36 am ]
Post subject:  Re: AO and SSD

Interesting, so Premium mode is not supported, but min/max is supported by CLI? 3par really needs to get their act together with this stuff.

Author:  cali [ Thu Nov 26, 2015 9:24 am ]
Post subject:  Re: AO and SSD

It seems that the AO Premium Mode was planed in 3.2.2, but not implemented.
In fact I set the Premium Mode and it did not work.
Error: can't read "ao_mode": no such variable

Now found a hint in the 3.2.2 MU1 Release note:

149461 HPE 3PAR OS 3.2.2 incorrectly allows the premium mode to be set to an AOCFG object, but it will fail AO scheduled tasks with premium mode.
The functionality was removed but the setting was not.


Author:  T16 [ Tue Jan 12, 2021 9:10 pm ]
Post subject:  Re: AO and SSD

Premium mode does not exist, it never went into production.

We had the same issue, ~6TB of SSD space begging to be used, AO even in performance mode would only use ~600GB out of this.

The answer is to give your aocfg a minimum to fill up the SSD Tier:-

In addition to disabling the raw space alerts when the entire SSD tier is used only for AO, a tier minimum value can be set. 3PAR InForm OS 3.2.2 and later includes the ability to set tier minimum and maximum values. These options were designed to address the use case of an environment where all SSD space is dedicated to AO. Use this option by first calculating the usable space in the SSD tier available to AO. A configuration of 8 x 480 GB MLC SSDs in a RAID 5 CPG, for example, results in about 2.6 TB of usable space available to AO. Specify this as the tier minimum for AO with a command such as setaocfg –t0min 2.6T CPG_SSD_r5. Tier minimum and maximums may also be set with the createaocfg and startao commands.

I have set 768GB for AFC, and set about 5TB to be used for AO. No clue if our AFC stats are any good or not, thats the next thing to review and tweak.

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