EVA LUN ALLOCATION

[pkumar97]

am attaching some screenshots with this post
Please check the details and suggest me how we can allocate these disk via controller b , becasue it is currently through controller A , Also pelase tell me how we can change
Host LUN SCSI Reservation
AGIMX1 6 None
AGIMX2 6 None
scsci reservation becasue it is currently none it should be like Regular .

[pkumar97]

Am attaching the sheet

[Santhosh D]

Hi,

First of all, please let us know what HSV Controller is it

Because in early generations like EVA 3k and 5k, we had this utility called SCSI reservation which was in use. For example, if you have a VDISK where Controller A is the Master, then the Host has to access the ownership from the Master always and then release it.

But in new generations, we dont have that function any more, any Host wich is presented to that LUN can access that VDISK wothout changing the Ownership.

This technology applies when Master Controller fails also. The Slave controller will take over the ownership.

[pkumar97]

currenty we are using EVA4000

[pkumar97]

can any one please have a look on this

[Uwe Zessin]

> this utility called SCSI reservation which was in use.

SCSI reservations have *NOTHING* to do with the internal virtual disk management ownership of a controller. They are used by some host operating systems (Windows Clusters, Tru64 Unix Clusters, VMware ESX server, sometimes IBM AIX) to serialize access to a disk.

[Víctor Cespón]

You currently have the vdisk Preferred path/mode set to "No preference", so the control is from the multipath software on the server.

The vdisk will stay associated to controller A until the multipath software changes it, or more than 60% reads come from controller B and the EVA changes it.

AGIMX1 and AGIMX2 are the servers to which this vidks is presented.

Regarding "SCSI Reservation", why do you need to change it? Where's documented?

[pkumar97]

vcespon ,
Am asking whether we need to do anything with that i mean regarding " scsi reservation " . I just want to cross check with you guys anything wrong with the allocation .

Am attaching the vdisk details once again . Please verify this . if anything wrong please suggest how we have to rectify

[pkumar97]

attached sheet

[Dennis L W Thury]

I assume you have MPIO installed on the 2 servers (AGIMX1 & AGIMX2). I further assume these 2 servers are clustered.

You could set the preferred path for this disk from within CV by selected the desired value for "Preferred path/Mode" under the presentation path. But that's not what I'd do.

I'd run MPIO CLI on each server, and issue the command sequence:
"hpdsm devices"

"hpdsm device=n paths"

"hpdsm device=n path=m"

Notice that this will disable any load-balancing policy on that disk, which I don't think is a good idea.

Instead, I'd set an appropriate load balancing policy (I tend to use SQST, meaning use the path that has the shortest queue based on the service time of that path. I'd also be sure ALB is enabled.

Hope this helps,