eva3000 and primary/alternate paths on hpux11i

[Charles McCary]

Hi - I'm familiar with the old autoraid luns where you would alternate paths in the volume group to achieve load balance across controllers. I'm also familiar with the va7100 where you only use the performance path as the primary path in the volume group (although, I've heard recently that they've changed their minds on this).

Anyway, we're about to order an eva3000 and as mentioned above will have hosts running 11i connected to it. What's the prevailing theory for the eva3000, do you alternate paths within the volume group or not? I did read where load balancing across the controller was recommended, but you could conceivably do this without alternating within the volume group by having one volume group go to one controller and another volume group go to another. Maybe it doesn't really matter as long as it's balanced?

[Zygmunt Krawczyk]

Hi Charles,

eva3000 with HP-UX 11i requires Secure Path software

http://h18006.www1.hp.com/products/sanworks/secure-path/hp-ux.html

Secure Path is multi software and can balance the workload among available paths and eva controllers.

Regards,
Zygmunt

[Charles McCary]

Zygmut,

hi - yes I'm aware of the secure path requirement, however that doesn't alleviate the volume group setup does it?

[RAC_1]

The alternate paths are exactly for load balancing, but for fail over. You are right in thinking that if you have two controllers, you can a vg going through one controller and another VG through other controller.

You can do that for LVs also. One LV with one primary controller and on other lv, another as primary.

The softwares like ecure path (vxvm - dynamic multipathing, EMC power path) do failover and load balancing.

Anil

[Prashant Zanwar_4]

Yes in addition to above discussion, when hou have mirroring you use disks from two different controllers which not only gives you data redudency on disks but on controllers also.
Also we use alternate pathing term for one disk. This means disks has multiple paths, which further adds up to redudency.

Similarly we can use it in reverse, one path as primary to one disk, other path primary to other disk and same with secondary.

There are disk arrays capable of connecting to number of connectors(Fibre/SCSI..)..
Here the term of LUN comes into picture. LUN number changes as per the PATH of controller or the same disk or so.
Correct me if I am wrong.

Hope the above helps atleast somewhere.
Prashant

[Francis_12 · Accepted solution]

Hello,

The SecurePath software allows you to do load-balancing on the EVAs.


The only way to do load balancing with EVAs is to use the SecurePath software :
http://h18006.www1.hp.com/products/sanworks/secure-path/index.html

In your case, you will need SecurePath 3.0d for hp-ux 11iv1 :
http://h20000.www2.hp.com/bizsupport/CoreRedirect.jsp?targetPage=http%3A%2F%2Fh200006.www2.hp.com%2Fbc%2Fdocs%2Fsupport%2FSupportManual%2Fc00059258%2Fc00059258.pdf

Please read carefully the pdf page 25 where the load balancing/failback mechanisms are detailed.

Hope this helps,

Bye.

Francis.