EVA 4000 poor performance

[Christ 33]

Hello,

We have an EVA4000 2C4D with 54 discs (mix 146 FC, 250 FATA and 500 FATA).
Same slot for each enclosure for each disc category.
We have poor performance in copy mode: less than 90 mo/s, from windows servers. I tried a test from the Manap to copy 6 files of 1.7 Gb. From C: to C:, it was faster than from C: to EVA! During the test, there was nobody else than me on the SAN. I have redone the test with evaperf command running. I copied from C: to 146 Gb FC group, to 250 Gb FATA, to 500 FATA and from 250 FATA to 146 Gb FC (Full SAN). The result was between 53 and 103 Go/s for the EVA (poor value). Time latency was between 2 and 6 ms (very good value).
These times latency, was only for my copy. During a test, I tried to send request from another server to an Oracle data base which was on the SAN. In this case, the time latency for theses requests was between 20 an 40 ms! During all these tests, controller CPU usage stayed under 15%
I run at the same time SanHealth on the switches Brocade, but I donâ t see different information.

It seem that there is a bottle neck somewhere, but I dontâ s see where!

How do you explain this strange result?

See attach the SAN drawing.

[Thomas J. Harrold]

Can you describe how you have configured your disk groups? How many of each drive type?

I've learned that EVA performs best (generic workloads) with >32 drives per disk group.

From everything I've read, don't rely on the FATA disk groups for anything other than disk-disk backup, or archival.

-tjh

[Christ 33]

Thanks for your answer.

I have 56 discs in 4 enclosures.

26 FC discs 146 Go 15k
19 FATA 250 Go
11 FATA 500 Go

I made an error when I told about -Same slot for each enclosure for each disc category-. Somewhere, there is a mix.

We have 3 discs groups, one for each disc type.
We use FC disc for database Oracle 10g, FATA disc to make disc to disc to tape.

[Thomas J. Harrold]

No issues with mixing disk types per slots or enclosure. As long as each disk type is in it's own disk group, you should be OK.

(26) 146GB drives is not too bad. When you setup your test, did you use vraid5, or vraid1?

How many virtual disks are configured in that disk group (146GB)?

-tjh

[Christ 33]

We have 50 luns in Vraid 5
In user guide HP say: -- Disk drives should be installed in vertical columns within the disk enclosures --. Do you think that this will impact the performance if itâ s not?

[Thomas J. Harrold]

The "vertical column" suggestion is to ensure that you do not simply install disks within 1 shelf. As long as the shelves are equally balanced, you should be OK. Usually disks are installed in groups of 8 (minimum required for a disk group). In that case, you'd want to install two disks per shelf in an EVA4000.

In your case, if you have (6) 146GB drives in each shelf, with two shelves each containing a 7th drive, you should be fine.

Why (50) vdisks? Are they all presented to different hosts?

-tjh

[Christ 33]

Yes, we have many servers (see attach), but we have really 5 Oracle servers which are really working on the SAN, specially one Windows cluster for the production.

[tkc]

Hi Christian,

Initiate a collection of the EVA performance objects with the following command from the DOS prompt of the SMA : evaperf all -cont -csv >data.csv

[Owen_15]

Hi Christian,

Let me start by stating what the maximum rated performance figures are for the EVA4000.

For a single controller - the maximum throughput is 335MB/s. This is from the quickspecs located at http://h18000.www1.hp.com/products/quickspecs/Division_01-2006/12234_div.PDF

From the same quick specs, the host ports are 2Gb/s, which provide approximatley 200 MB/s per host port. Of which the EVA4000 does have 4 ports in total, two on each controller.

This is where you need to be investigating exactly what sort of multipathing you have setup. Ie are you load balancing across both controllers down two different paths or are you perhaps only using one path. Because if you are using only one path, the maximum theoretical throughput is only 200 MB/s.

In regards to your file copy test, there are a couple of points you need to be considering that will be stopping it from achieving the maximum value
- block size of the file systems that you are using and of the files themselves being copied.
- the IO throughput that a file copy is creating (I would expect it to be significanlty less than what an Oracle DB can request).
- file system and logical volume disk buffers and queues.

All of these will be playing a part and a value of 90 MB/s from a straight file copy off the FC disk group is reasonable.

More advanced tests such as those in this white paper are better able to stress an EVA.
http://h71028.www7.hp.com/ERC/downloads/4AA0-5452ENW.pdf

Regards
Owen

[Amar_Joshi]

Just to add to Owen's detailed explanation.. IO block size does matter for different size of files. If your files are small and block size is big (or vise versa) you may hit a performance problem.

Also very basic thing to note is the WriteBack cache on all the Vdisks you have created.