topic Re: XP12000 external storage multipath in Disk Enclosures

XP12000 external storage multipath

Madis Rehepapp — Thu, 27 Jan 2011 11:02:01 GMT

XP External Storage Support document (http://h20272.www2.hp.com/utility/document.aspx?docurl=Shared%20Documents/hw/external_storage/P9500_XP24000_12000_External_Storage_Stream_external_2010_10_27.pdf) lists path mode as single for several storage arrays.

The XP External Storage Software User Guide (http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c02250769/c02250769.pdf) explains: "For Single mode, only the path with the highest priority (primary path) is used to execute I/Os to the external LU. When an error occurs in
the primary path, the path with the second highest priority is used (that is, no per-LU dynamic load balancing across paths)."

I understand that single mode is appropriate when the external storage is using asymmetric or active/passive controllers, but is there anything that would prevent you from configuring multiple active paths to the same primary controller and load-balancing between these paths to gain higher throughput? Ignoring the high availability issues for a moment, can path mode: multi be used with any given storage system when just connecting to one controller?

Re: XP12000 external storage multipath

Jan Soska — Mon, 31 Jan 2011 10:35:40 GMT

hello, check this multipath for windows os:
http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=421493〈=en&cc=us&prodTypeId=18964&prodSeriesId=421492&taskId=135

jan

Re: XP12000 external storage multipath

Madis Rehepapp — Mon, 31 Jan 2011 10:37:52 GMT

How would Windows Multipath documentation help here? I am talking about connection between two storage systems, not server and storage.

Re: XP12000 external storage multipath

Jan Soska — Mon, 31 Jan 2011 10:41:59 GMT

Ah, sorry, I missed the point... :(

Jan

Re: XP12000 external storage multipath

Alzhy — Mon, 31 Jan 2011 14:06:57 GMT

We have EVA8XXX's hooked up to our XP12000. The EVAs serves as external storage to the XP12K as primarily serves as 2nd Tier SVOLs for split mirror backups and clones of production.

What we have done is we alloacte 2 ports from each EVA controller and zone them to 4 ports on the XP12K CHiP ports (one for one). I can no longer remember what path settings we've set them to but everything's been working well.

Note these EVAs are ALUA (assymetric active/active).

Re: XP12000 external storage multipath

Madis Rehepapp — Mon, 31 Jan 2011 14:15:50 GMT

Alzhy, thanks, that's the kind of info I'm looking for.
Do you do load balancing between the two EVA ports and have the two ports on the other controller as standby? Or is it really only one connection active at any given time?

Re: XP12000 external storage multipath

Alzhy — Mon, 31 Jan 2011 14:20:01 GMT

I have never really observed to be honest. What we do is we have path preferencing on the EVA and alternate preferencing between the 2 controllers... i.e. esVdisk1 on HSV-A, esVdisk2 on HSV-B, esVdisk3 on HSV-A.. so forth...