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sysman io rebuild and EMC device configuration

 
Bill Hall
Honored Contributor

Re: sysman io rebuild and EMC device configuration

Dave,

$1$$DGA devices will remain around until the entire cluster is shutdown.

What is or where is the performance issue?

Bill
Bill Hall
Shriniketan Bhagwat
Trusted Contributor

Re: sysman io rebuild and EMC device configuration

Hi,

I am just thinking, will below commands help to solve the problem?

$ MC SYSMAN
SYSMAN> SET ENV/CLUSTER
SYSMAN> IO SCSI_PATH_VERIFY
SYSMAN> IO AUTOCONFIGURE
SYSMAN> EXIT
$
$

Regards,
Ketan
Ian Miller.
Honored Contributor

Re: sysman io rebuild and EMC device configuration

SYSMAN IO SCSI_PATH_VERIFY disconnects the paths to devices no longer available.
____________________
Purely Personal Opinion
Dave PNCGIS
Occasional Advisor

Re: sysman io rebuild and EMC device configuration

I have also contacted EMC. This is their take on why we have the issue. It sounds like IO SCSI should fix this:

EMC:
When OpenVMS boots or when using SYSMAN to scan the SCSI bus, OpenVMS replaces all it knows about storage with the new information supplied by arrays about what devices have been presented to that host. From then on OVMS uses that information to find devices and paths. Periodically OVMS queries devices to see if they are still there. If they respond in time, all is well. If not then OVMS goes into the mount verify process. That takes time and affects performance on all devices. I expect that mount verify errors would be logged in syslog.sys for the missing devices.

Follow HP's recommendations. This issue has nothing to do with the array. It is the way OpenVMS behaves. Just as you have to scan the bus to make newly provisioned devices known to OpenVMS, you have to scan the bus to make OpenVMS forget about devices removed.
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The Brit
Honored Contributor

Re: sysman io rebuild and EMC device configuration

Hi Dave.

It sounds like a bit of double-talk to me. I would assume that you are not going to un-configure EMC Luns while they are mounted on the VMS system. And if they are not mounted, then "mount-verify", and any associated performance problem, is not a consideration.

I know they say it has nothing to do with the storage array, however OpenVMS behaves exactly the same with other compatable storage arrays, HSG, EVA, XP, etc (all HP of course), and these arrays do not experience any "performance" issue. LUNs are often "presented" and "unpresented", sizes modified, etc, and no performance issues are observed or experience.

Of course I might just be lucky.

I have no experience with EMC storage, however I do know several sites which use it, and most report "peculiarities" when using this storage with OpenVMS.

Just my 2c worth.

Dave