HPE EVA Storage

EVA 6110 with FC and FATA groups - Slow!!

 
Timjade
Advisor

EVA 6110 with FC and FATA groups - Slow!!

Hi guys, can you please help on a topic that was inevitable.

Our client has an EVA 6110 with FC and FATA disks.

Windows 2003 64 R2 and Windows 2008 R2
OS's are connected to it via Qlogic QMH2462 4Gb FC HBA's.

These are blade servers.

Now, the problem is the speed of the EVA.

Load and capacity have recently increased significantly, we are using nearly all of the 35TB worth of disks and there are nearly 1000 concurrent users connected to our database.

My questions are:
Will the capacity have an effect on performance? (I have heard mixed results) ie. There is not much available free disk...

The problem is most likely contention from other systems contending for IO. How can we get some good tests? EVAPerf?

Thanks.
22 REPLIES 22
Johan Guldmyr
Honored Contributor

Re: EVA 6110 with FC and FATA groups - Slow!!

Hi!

There's quite a big difference between the FC and the FATA disks.
FATA disks are about 1/3 as fast as the FC disks.

A lot of times the performance is not fast because the vdisks are not balanced between the EVA controllers. You can see which is the owner by looking under presentation.
Some times the vdisk are balanced 50/50, probably also good to balance them based on load.

Are both DGs full? How many disks/disk type and how much free space do you have?
I believe HP recommends to have an occupancy around 95% but that it may be possible to do with higher if you have many disks.
Uwe Zessin
Honored Contributor

Re: EVA 6110 with FC and FATA groups - Slow!!

What data is stored on the FATAl disk drives and what is the access pattern? These drives are NOT meant as a cheap replacement of 'real' disk drives for servers that "don't need fast I/O".

This usage can damage the drives and it can slow down the whole array, because valuable cache space is blocked - try to turn of writeback caching on all virtual disks stored in FATAl disk groups.
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Timjade
Advisor

Re: EVA 6110 with FC and FATA groups - Slow!!

Hi, thanks for your replies.

the FC DG is about 99% full, the FATA DG is about 90% full.

I'm aware that the load on the controllers might not be optimal at the moment, especially when MPIO isn't configured properly on the Win2k8 R2 boxes to use full multipaths optimizing all 4 possible paths to the EVA. We are seeing one controller take most of the work and the other controller not doing much! I have a case logged with HP regarding configuring MPIO to properly load balance, I believe it should be (round robin with subset and all paths=Active/Optimized?) currently 2 paths are Active/Optimized and the other 2 are Active/Unoptimized.

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The data is mainly databases (Jade databases to be exact) they are large object oriented DB's, there isn't many small files.
The FATA DG's are used for test and the FC DG's are used for production.
Johan Guldmyr
Honored Contributor

Re: EVA 6110 with FC and FATA groups - Slow!!

I'm not sure about the terminology for the multipathing, but for the EVA it would be best if all hosts that are accessing the same LUN/vdisk is doing so via the same controller.

ALB .. ALP? Is that what it was called? The multipathing algorithm that senses which path is going to the owning controller.
Timjade
Advisor

Re: EVA 6110 with FC and FATA groups - Slow!!

Oh and there are 61 FATA disks (279GB) and 31 FC disks (465GB)

All VDisks:
Preferred path/mode: No preference
Uwe Zessin
Honored Contributor

Re: EVA 6110 with FC and FATA groups - Slow!!

Adaptive Load Balancing - if enabled, it should only do I/O through the paths that lead to the controller which owns the virtual disk. This avoids additional traffic through the non-owning controller and the mirror ports.
Especially proxied read I/Os are bad.

Non-preferred means that the EVA does a round-robin assignment during boot, but hosts with 'non-optimal' MPIO settings can kill that and in the extreme case force ownership of all vdisks to one controller.
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Timjade
Advisor

Re: EVA 6110 with FC and FATA groups - Slow!!

Would it not be optimal to have a LUN with both controllers doing equal amount of work? instead of just having one controller do all the work?
Timjade
Advisor

Re: EVA 6110 with FC and FATA groups - Slow!!

So what do you suggest?

I need to setup MPIO on the server(s) for all paths to Active/Optimized? (as only 2 paths are at the moment)
Uwe Zessin
Honored Contributor

Re: EVA 6110 with FC and FATA groups - Slow!!

IF by "LUN" you mean "virtual disk", the EVA is an "asymetrical active/active array". That means disk I/O for a given virtual disk is only done by the controller which 'owns' that disk.

If a host does read I/Os through the non-owning controller, this one asks the owning controller to 'pick up' the data from the disks and sends it back through the mirror port.

What you want to do is:

- configure ownership (=path preferrence in CV-EVA) to divide all vdisk across both controllers)

- turn on ALB in the MPIO.

This makes sure that I/Os are only using the "optimized" paths and the "non-optimized" ones only used in case of a failover.
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