Discussion:
[Veritas-vx] VMAX Auto-provisioning group devices & veritas ebn naming scheme
Hari Vemuri
2011-05-28 06:21:47 UTC
Permalink
Hi

When such name inconsistency occurs, you can run "vxddladm assign names" to refresh the names without the need to turn off naming persistence.

With regards
Hari
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Today's Topics:

1. VMAX Auto-provisioning group devices & veritas ebn naming
scheme bug (***@inform.gazprom.ru)


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Message: 1
Date: Fri, 27 May 2011 16:25:57 +0400
From: <***@inform.gazprom.ru>
Subject: [Veritas-vx] VMAX Auto-provisioning group devices & veritas
ebn naming scheme bug
To: <veritas-***@mailman.eng.auburn.edu>
Message-ID:
<***@MAIL.adm.gazprom.ru>
Content-Type: text/plain; charset="utf-8"



Hello all!



The traditional symmaskdb technology was replaced with Auto-provisioning Groups (see Solution Enabler Symmetrix Controls CLI 7.2)



Just noticed an interesting bug when configuring veritas disks on thin devices combined in storage groups. When adding a symdev A (thin device

for sample) to the symmetrix storage group a new lun id is presented to the symdev A. When removing this symdev A from the storage group this lun id can be used by another newly added symdev B. When giving back the symdev A to the storage group it is presented with the new lun id. As a result Veritas gets two identical ebn disk names which can lead to some very bad things. There can be two workarounds:

1) Using reserve lun id option for symdev on symmetrix storage group to exclude any confusion about lun ids;

2) vxddladm set namingscheme=ebn persistence=no use_avid=yes



I think the best option is number 2. But no sure about potential problems because of changing default persistence (=yes) meaning



Any suggestions?



Regards, Pavel Tsvetkov



P.S. about this option from man pages:







persistence

Specifies whether the names of disk dev-

ices that are displayed by VxVM remain

unchanged after disk hardware has been

reconfigured and/or the system rebooted.



If persistence is on, the DDL assigns device names

from the persistent device name database, rather

than generating new names according to the OSN or

EBN naming scheme.



If the naming scheme is OSN, name persistence is

off by default. The generated names are not likely

to differ from the names in the persistent name

database, unless a change causes the OS to assign

a new path name for a device.



If the naming scheme is EBN, name persistence is

on by default. Certain configuration changes on

the array side could cause the generated name to

be different from the name in the persistent name

database. When name persistence is on, the name

from the persistent names repository is used for

the DMP meta-device, unless

the user changes it. .



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P***@inform.gazprom.ru
2011-05-30 04:53:15 UTC
Permalink
Hello Hari

Thank you for the reply.

Yes, it is possible to correct wrong duplicate veritas disk names. For example one cam remove disk.info file and
issue vxconfigd -k to rebuild disk configuration. But it can be too late because of incorrect disk names errors. One of the disks suddenly gets failed for example. I want to keep this from happening.

With regards
Pavel
Hi
When such name inconsistency occurs, you can run "vxddladm assign names" to refresh the names without the need >to turn off naming persistence.
With regards
Hari
-----Original Message-----
From: veritas-vx-***@mailman.eng.auburn.edu [mailto:veritas-vx-***@mailman.eng.auburn.edu] On Behalf Of veritas-vx-***@mailman.eng.auburn.edu
Sent: Friday, May 27, 2011 10:30 PM
To: veritas-***@mailman.eng.auburn.edu
Subject: Veritas-vx Digest, Vol 58, Issue 12

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Today's Topics:

1. VMAX Auto-provisioning group devices & veritas ebn naming
scheme bug (***@inform.gazprom.ru)


----------------------------------------------------------------------

Message: 1
Date: Fri, 27 May 2011 16:25:57 +0400
From: <***@inform.gazprom.ru>
Subject: [Veritas-vx] VMAX Auto-provisioning group devices & veritas
ebn naming scheme bug
To: <veritas-***@mailman.eng.auburn.edu>
Message-ID:
<***@MAIL.adm.gazprom.ru>
Content-Type: text/plain; charset="utf-8"



Hello all!



The traditional symmaskdb technology was replaced with Auto-provisioning Groups (see Solution Enabler Symmetrix Controls CLI 7.2)



Just noticed an interesting bug when configuring veritas disks on thin devices combined in storage groups. When adding a symdev A (thin device

for sample) to the symmetrix storage group a new lun id is presented to the symdev A. When removing this symdev A from the storage group this lun id can be used by another newly added symdev B. When giving back the symdev A to the storage group it is presented with the new lun id. As a result Veritas gets two identical ebn disk names which can lead to some very bad things. There can be two workarounds:

1) Using reserve lun id option for symdev on symmetrix storage group to exclude any confusion about lun ids;

2) vxddladm set namingscheme=ebn persistence=no use_avid=yes



I think the best option is number 2. But no sure about potential problems because of changing default persistence (=yes) meaning



Any suggestions?



Regards, Pavel Tsvetkov



P.S. about this option from man pages:







persistence

Specifies whether the names of disk dev-

ices that are displayed by VxVM remain

unchanged after disk hardware has been

reconfigured and/or the system rebooted.



If persistence is on, the DDL assigns device names

from the persistent device name database, rather

than generating new names according to the OSN or

EBN naming scheme.



If the naming scheme is OSN, name persistence is

off by default. The generated names are not likely

to differ from the names in the persistent name

database, unless a change causes the OS to assign

a new path name for a device.



If the naming scheme is EBN, name persistence is

on by default. Certain configuration changes on

the array side could cause the generated name to

be different from the name in the persistent name

database. When name persistence is on, the name

from the persistent names repository is used for

the DMP meta-device, unless

the user changes it. .



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