Re: Mixing FastT hdisks and ESS vpaths

That's exactly what we are doing here. Using SVC in the fabric and bringing
on some FastT disks in an ESS environment. The fact that the FastT sits
behind the SVC and the AIX node uses SDD to communicate with the SVC gets
around any RDAC / SDD concerns.




Jeff
Barratt-McCartney
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<aix-l@Princeton. Subject
EDU> Re: Mixing FastT hdisks and ESS
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12/05/2006 07:36
AM


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IBM AIX
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I agree with simon. As a business partner, one of our major functions is
data migration, and this is the preferred method.

I assume the business partner is recommending that the RDAC controlled
(FAStT) disk will be presented over a seperate set of HBAs(RDAC/SDD have
conflicts).

Another option for online migration with minimal service outtage involves
the implementation of SAN Volume Controllers; creating SVC image-mode disks
of the ESS disk, and then migrating them to SVC controlled FAStT vdisks.
This doesnt require a seperate set of HBAs(SVC uses SDD), and requires only
a minimal outtage to convert the ESS disk to SVC image-mode disks. This
method has been extremely successful for me, and is considerably less work
than using mklvcopy/migratepv








-----Original Message-----
From: IBM AIX Discussion List on behalf of Green, Simon
Sent: Tue 12/5/2006 5:19 AM
To: aix-l@xxxxxxxxxxxxx
Subject: Re: Mixing FastT hdisks and ESS vpaths

I've never heard of such a thing and it seems very unlikely. LVM
doesn't care what sort of disks they are - that's half the point of
having it in the first place: so you deal with Logical not Physical
storage. One could probably make a case that it's not a great idea from
a long-term storage management perspective, but I can't see anything
wrong with it as a transitory solution.

--
Simon Green

-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@xxxxxxxxxxxxx] On Behalf Of
AIX Geek
Sent: 04 December 2006 23:05
To: aix-l@xxxxxxxxxxxxx
Subject: Mixing FastT hdisks and ESS vpaths


Can anyone point me to some documentation that says that FastT hdisks
and ESS vpaths should *NOT* be mixed in a volume group?

Planning a migration (from Shark onto FastT) and the proposal on the
table from a business partner is to add the FastT hdisks to the VG and
mirror. Conceptually, it's OK. But other sources have called out the
fact that IBM doesn't support FastT hdisks and ESS vpaths in the same
volume group.

True, false, or true-with-caveats?

Relevant Pages

  • AW: System thrashing?
    ... the tape robot while the other 2 are used for both ESS and FAStT (via a SAN ... does SVC stand for (I only know the abbreviation in connection with ATM ... Subject: AW: System thrashing? ...
    (AIX-L)
  • Re: AW: System thrashing?
    ... How is it that you have the same box connected to both an ESS and a FAStT ... Subject: AW: System thrashing? ...
    (AIX-L)
  • Re: Shark, FastT Splitlvcopy VS EMC BCV
    ... the Symms that we work with seem to require frequent outages for bin ... file changes and code updates. ... The FastT is more of a mid-range product, and not as robust as the ESS. ...
    (AIX-L)
  • Re: Migrating to FastT
    ... Subject: Migrating to FastT ... physical disks, and there is an exported volume group on them. ... If I had only one adapter, and saw only 12 disks, I would go ahead and ...
    (AIX-L)
  • Re: FAStT connected AIX host
    ... FASTT LUNs to the same adapters. ... SDD and RDAC will battle. ... 80 GB LUNS fine but it has problems with the 160GB. ... connected to an ESS Shark so it does have the 2105 filesets and SDD ...
    (AIX-L)