Hi
On top of what has been mentioned here (RAID <-> BS aligment, and many other things) I would suggest to look at the last 4/5 slides of a 2018 (disclaimer: my own) London UG presentation http://files.gpfsug.org/presentations/2018/London/14_LuisBolinches_GPFSUG.pdf
It gives a start on different storage subsystems and full stripe write and those things that do not matter, ... until they do.
But I agree that on top of whatever that Protect process was doing there might be ways of improvement here. Enjoy the ride.
--
Ystävällisin terveisin / Kind regards / Saludos cordiales / Salutations / Salutacions
Luis Bolinches
Ystävällisin terveisin / Kind regards / Saludos cordiales / Salutations / Salutacions
Luis Bolinches
Consultant IT Specialist
IBM Spectrum Scale development
ESS & client adoption teams
Mobile Phone: +358503112585
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----- Original message -----
From: "Valdis Klētnieks" <[email protected]>
Sent by: [email protected]
To: gpfsug main discussion list <[email protected]>
Cc:
Subject: [EXTERNAL] Re: [gpfsug-discuss] Client Latency and High NSD Server Load Average
Date: Sat, Jun 6, 2020 08:38
On Fri, 05 Jun 2020 14:24:27 -0000, "Saula, Oluwasijibomi" said:
> But with the RAID 6 writing costs Vladis explained, it now makes sense why the write IO was badly affected...
> Action [1,2,3,4,A] : The only valid responses are characters from this set: [1, 2, 3, 4, A]
> Action [1,2,3,4,A] : The only valid responses are characters from this set: [1, 2, 3, 4, A]
> Action [1,2,3,4,A] : The only valid responses are characters from this set: [1, 2, 3, 4, A]
> Action [1,2,3,4,A] : The only valid responses are characters from this set: [1, 2, 3, 4, A]
And a read-modify-write on each one.. Ouch.
Stuff like that is why making sure program output goes to /var or other local file
system is usually a good thing.
I seem to remember us getting bit by a similar misbehavior in TSM, but I don't
know the details because I was busier with GPFS and LTFS/EE than TSM. Though I
have to wonder how TSM could be a decades-old product and still have
misbehaviors in basic things like failed reads on input prompts...
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