Changing the Managing controller for a vdisk

[k20pattu]

Gurus,

On EVA5000 (VCS4100) with a single diskgroup of 56x146GB and 56X300GB FC disks, there exists about 92 vdisks. While running EVAperf recently we noticed that all the vdisks bar one are managed through only one controller. Second controller is virtually sitting there idle.

This is the EVA where users always complained of slow performance and now we might be able to relate the slow performance to all IOs going through a single controller (different sizes disks in diskgroup are not performance issue because other such similar EVAs are ok).

We could not find any way to change the managing controller - in fact CV doesnt give option to change the controller (whether while creating a vdisk or while presenting it). Looks like CV itself picks up the controller.

Can anyone please shed some light whether it is possible to change the controller for vdisks?

Thanks
Ketan

[IBaltay]

Hi,
if you change it via the presentation from None to Set preferred path (failover/failback) it will be changed. But if the host does not recognize the new managing controller it will continue to access the previous managing controller. Thus after 1 hour of intensive R/W via the proxy controller EVA switches the role back. To resume it, a) the path preference should be always set on EVA side. Then the preferred path should be inline with the LVM based systems (Unix/Linux) if they dont support the ALB. IF they ALB aware (MPIO), then it should be set to always recognize the managing controllere from the host side...

[k20pattu]

Thanks! Currently Controller A is the managing controller. So if I change the preferred path/mode from "No Preference" to "Path B-Failover/Failback", it should cause the Controller A to divert all IOs to Controller B and eventually EVA5K will change managing controller to Controller B?

Please correct me if my interpretation is incorrect.

Regards,
Ketan

[IBaltay · Accepted solution]

yes,
but it should be done in a IO silence period, when there is no IO on the appropriate vdisks...

[SriniHP]

Changing the path preferance to No_Preferance is that non-disruptive? or is it require downtime?

[RBhat]

For EVA 8400, In order to change the path preference of the vdisk , is it require downtime ?