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VMAX Host IO limits
I am looking into an issue where the Host IO limits are set on a storage group, in this case they are set to 800MB/s and 15000 IO/s, everything looks to be configured correctly for the storage group, I can see that each FA port in the port group has a limit of 3750 IO/s just as expected. Now for some reason the limits appear to be restricting the IO/s to 1500.
Quincy561
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January 20th, 2015 06:00
Host IO limits works on a very granular level, in seconds at most. So if you are looking at longer averages, the limit may seem lower because of host IO bursts.
Quincy561
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January 20th, 2015 07:00
It is not uncommon to see a big burst of IO for very short periods, then a much longer period of no IO. I would suggest opening a case and have someone look at your system if you are interested in finding out what is going on. A CDB trace may be needed to see if there are such bursts.
Anonymous
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January 20th, 2015 07:00
Yes I can see that from other samples, but in this case it is a factor of 10 out, I can see a consistent line where the host IO is at 1500 and at that point I can see the delayed IO % go up to around 70% and the response times increase, I had to double check the settings as this looks just like it should be set for 1500, but it's not, it is set for 15000.