Does enabling multipathing degrades backup performance to disk storage unit created on SAN disks

[arun660]

Hi Guys,

Need some info:

Does Backup performance degrades when multipathing is enabled for the SAN disks used for creating the disk storage unit?

Thanks in advance for your comments.
 

[Marianne]

It all depends on the array type multipathing capabilities and the type of multipathing software used.

If array supports active/active multipathing, performance will be increased.

If active/passive only, it will have no effect on performance.

[arun660]

Hi Marianne,

Thanks for your reply.

However, does any of the configurations decreases the backup speed or time when multipathing is enabled?

I am not bothered even if it is not increased, but it should not decrease the backup speed and time.

[Marianne]

Please firstly find out what type of multipathing software you are using and the multipathing config options.

If DMP that is part of VxVM (Storage Foundation), there are no multipathing options that I'm aware of that will decrease performance.

[Nicolai · Accepted solution]

If your SAN has multiple path using multipathing software is mandatory. Else a down path in the SAN will cause I/O errors on the storage unit.

I am not aware of any multipathing causing performance decrease - I would say it causes a performance increase since the multipathing software monitor the I/O queue for each path and balance the load according to the queue.

[novonil_choudhu]

DMP :

An input/output (I/O) enhancement technique that balances I/O across many available paths from the computer to the storage device to improve performance and availability.

A feature of Veritas Volume Manager that provides greater reliability and better performance by using path failover and load balancing for multiported disk arrays connected to host systems through multiple paths. DMP detects the various paths to a disk using a mechanism that is specific to each supported array type. DMP can also differentiate between different enclosures of a supported array type that are connected to the same host system.

A feature of VERITAS Volume Manager designed to provide greater reliability and performance by using path failover and load balancing for multiported disk arrays connected to host systems through multiple paths. DMP detects the various paths to a disk using a mechanism that is specific to each supported array type. DMP can also differentiate between different enclosures of a supported array type that are connected to the same host system.

A feature designed to provide greater reliability and performance by using path failover and load balancing for multiported disk arrays connected to host systems through multiple paths. DMP detects the various paths to a disk using a mechanism that is specific to each supported array type. DMP can also differentiate between different enclosures of a supported array type that are connected to the same host system.

An enhancement technique that provides the load balancing and path failover to disks that are connected to the Scalable File Server cluster nodes.

[Marianne]

Please always include the URL or document that you are quoting from.

I guess it is this one?
 http://www.symantec.com/security_response/glossary/define.jsp?letter=d&word=dmp-dynamic-multipathing

[novonil_choudhu]

Yes correct @Marianne this is the url. Aplogies for not pasting the url