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Persistant dfs

 
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Timothy P. Jackson
Valued Contributor

Persistant dfs

Hi Everyone,

Is there any difference between the new Persistant dfs and the legacy dfs?

Can you mix them when you setup a logical volume?

Is there a performance difference?

Thanks,
Tim
6 REPLIES
Kenan Erdey
Honored Contributor
Solution

Re: Persistant dfs

Hi,

check this document.

http://www.scribd.com/doc/40054087/Persistent-Dsf-Migration
Computers have lots of memory but no imagination

Re: Persistant dfs

as such there is no difference between Persistant dfs and the legacy dsf , is just there is a change in the naming convention in 11iv3,
Ismail Azad
Esteemed Contributor

Re: Persistant dfs

Hi tim,

There is a pretty significatn_difference between persistent and legacy DSF. The "inbuilt" native multipathing feature on 11.31 now would normally see the LUN as the "LUN" itself. Legacy DSF's are based on "lunpath". 8 paths to the LUN give you 8 legacy DSF's but only one persistent DSF for that LUN. You_can mix them up as long as they are referring different LUNs or disks. However, this is not_recommended. Use the "persistent" DSF wherever possible. Legacy DSF's are present only for "backward compatibility". In terms of LVM there is a beautiful script called as vgdsf that allows for this migration.

> Performance difference

Agile addressing definitely provides better performance with default allocation policies which can be manipulated with the command scsimgr. PV links are definitely getting_deprecated.

Regards
Ismail Azad
Read, read and read... Then read again until you read "between the lines".....
Torsten.
Acclaimed Contributor

Re: Persistant dfs

AFAIR there was a doc telling the system does multipathing with legacy device files too, but strongly recommends the new style device files.

Hope this helps!
Regards
Torsten.

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Ismail Azad
Esteemed Contributor

Re: Persistant dfs

Hi,

>Torsten

Yes... a parameter called as leg_mpath_enable.

Regards
Ismail Azad
Read, read and read... Then read again until you read "between the lines".....
Timothy P. Jackson
Valued Contributor

Re: Persistant dfs

Thanks everyone for your input. I guess I will have to get up to speed with the new technology.

Sorry it took so long to assign points!

Thanks again!

Tim