P4500 + Linux Scheduler

[Patrick Neuner]

Hello,

I wanted to ask if someone here got practical experience what IO Scheduler is best to use with Linux running on P4500.

Right now we use the standard scheduler CFQ. But I read some articles where NOOP or DEADLINE are prefered ...

Not sure how reliable those articles are ... and if NOOP or DEADLINE would fit better for P4500.

Speaking about Webservers (mostly apache + mysql + sendmail + dovecot)

Thank you

Andreas Schnederle-Wagner

[Patrick Neuner]

really no experiences about this?!?

At least on HP EVA SANs it can be a huge performance boost to choose the right Scheduler:

With large sequential reads, the default scheduling policy of cfq for Red Hat will yield approximately 50 percent less performance so it is a significant hit. The recommendation is to set I/O scheduler to noop or deadline .

--> http://bizsupport1.austin.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=110&prodSeriesId=3664583&prodTypeId=12169&prodSeriesId=3664583&objectID=c01783004 <--

Also Netapp is suggesting another IO Scheduler than the standard CFQ ...

But I can't find any recommendations for P4500 ...

[Cadonline]

As we are also using P4500 Volumes for our Linux Servers this is a quite interesting Question!

P4500 is based on LINUX too - so if I understand it right it would look like this:

Linux on P4500 Volume - CFQ (overhead of sorting the I/O)

P4500 based on LINUX - *not known which Scheduler* (maybe CFQ too?)

Storage Controller - does propper I/O sorting

So I guess it only produces overhead if you use CFQ on the presented Volumes - but it's just a guess and not know-depth!

Also no idea if NOOP or DEADLINE would work better in that case - I hope someone with more in-depth-knowledge can enlighten us here?

[Patrick Neuner]

Thank you for your Answer - I also think that CFQ only adds overhead but I'm not quite sure what IO Scheduler is best to use in this Scenario. I also don't find any offical recommendation from HP to this Topic ...

Still hoping someone knows "for sure" what's best to use ...

Andreas