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setting up new eva6400 .question about striping/vdisk path

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Frequent Advisor

setting up new eva6400 .question about striping/vdisk path

Hi all,

I need to setup EVA6400 with RHEL 5.6 .I need to create a single file system of 2 TB size .This file system is going to be 40% read and 60% write .It will be random read/write .

I am looking for your thoughts in order to get the maximum performance

1) What is the recommended vdisk size?
2) Will it be good idea to use the LVM striping on top of Vraid1 disk? If yes what are the recommended strip size and number of disk in the strip.
As per EVA best practice doc, it was advised that if the vdisk is owned by different controller, then it be advised to go with striping by using the volume manager.
3) How many disk path we can use per LUN for the optimum performance .with EVA 6400 we can have maximum of 8 Path per Lun (4 path per controller) ?
Will there be advantage of 8 path over 4 path ?

I am planning to create 100 GB of vidsk (vdisk1) and going to use LVM striping with -i 2 -I 4096.

Looking for your valuable suggestion.

Simon Hargrave
Honored Contributor

Re: setting up new eva6400 .question about striping/vdisk path

We personally don't stripe at the LVM level against our EVA's, primarily because the data is already spread evenly across all of your disks in your disk group. The only advantage to striping is to ensure both your controllers in an ALUA configuration are working as equally as possible.

You need to look at the usage of your EVA as a whole, not just this LUN or machine. If this will be the "main use", then it may be worth striping over 2 x 1TB LUNS, one owned by each controller. However if you have many TB published to many LUNs or hosts, then just make sure the IO is balanced equally across the controllers "for the whole estate".

As for paths, you can use as many as possible, the LUNs are published down all host ports. Set your zones up with all ports, and provided you're using dm-multipath with the correc multipath.conf then port balancing will be handled automatically with respect for your controller-LUN affinity.
Frequent Advisor

Re: setting up new eva6400 .question about striping/vdisk path

Hi Simon ,
thanks for the reply .

We wiill be presenting 2 TB each to 6 node in the redhat cluster .

So ,it is recommanded to avoid LVM striping in eva .The striping is not going to give you added advantage ?

And how about Vdisk size ?I am planning to give 100 GB's Vdisk1 for 2 tb File system .The IO is going to be random read and writes .
Honored Contributor

Re: setting up new eva6400 .question about striping/vdisk path

Go with 1x2TB Disk. Avoid LVM Stripes.
If you have to grow the file system - present new 100GB VDisk and just expand (concat) the LVOL. For additional space, just expand the 100GB Vdisk unti it reaches the 2TB max VDISK size.

Hakuna Matata.
Simon Hargrave
Honored Contributor

Re: setting up new eva6400 .question about striping/vdisk path

Yes I'd just use 2TB LUNs, 3 for each node on each controller.

Depending on how parallel your io's are, you may need to increase the queue depth on your hosts. The ql2xmaxqdepth in modprobe.conf (don't forget to mkinitrd as the qla2xxx driver will be loaded up in initrd).

You can verify and tweak the depth on the fly by reading and writing /sys/module/qla2xxx/parameters/ql2xmaxqdepth