on AIX more LUNs/hdisks is better. There are some resources allocated per 
hdisk, where you want more. Set up 4 or 8 VG's for database. Growing database 
filesystems is easier than adding more.

Op 15 jul. 2015, om 16:23 heeft David Bronder <david-bronder AT UIOWA DOT EDU> 
het volgende geschreven:

> Same number of LUNs in fewer VGs, or fewer LUNs, too?  The queuing concern
> makes it sound like fewer LUNs.  If so, as Rick says, that's also where your
> I/O concurrency would suffer.
> 
> If it's the same number of LUNs, using one VG per LUN makes it easier to
> isolate each LV to each PV rather than potentially mixing them all together,
> possibly having multiple LVs share the same PV, which could result in
> database I/O to different DB2 volumes hitting the same PV and causing extra
> contention.  (To be fair, in modern SAN arrays, the consumer host has no idea
> where any of the blocks really live in the back end, so that kind of
> contention can and probably often does happen anyway.)
> 
> My gut reaction with DB2 on TSM 6 and up is that nothing with the database
> layout is as easily fixed as it was with the embedded database in TSM 5 and
> earlier...  :-/  There's always trade-offs...
> 
> =Dave
> 
> 
> On 07/15/2015 09:15 AM, Rhodes, Richard L. wrote:
>> The concurrency I'm aware of is at the hdisk/lun level.  There's a 
>> num_cmd_elems at on the fcs adapter which we set to 2k, and then queue_depth 
>> on the hdisk.  That's why spreading I/O across as many hdisks/luns as 
>> possible is advantageous.
>> 
>> Rick
>> 
>> 
>> 
>> -----Original Message-----
>> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
>> Of Huebner, Andy
>> Sent: Wednesday, July 15, 2015 9:33 AM
>> To: ADSM-L AT VM.MARIST DOT EDU
>> Subject: Re: Disk layout for AIX
>> 
>> He claims there is a queuing issue with too many at the HBA.  I guess I 
>> missed that the last 12 years of being a storage/TSM admin.
>> I told him the theory of using many was to allow more concurrency.  Before 
>> we build I just want make sure this is not a mistake that cannot be easily 
>> fixed.
>> 
>> Thanks,
>> 
>> Andy Huebner
>> 
>> -----Original Message-----
>> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
>> Of David Ehresman
>> Sent: Wednesday, July 15, 2015 8:12 AM
>> To: ADSM-L AT VM.MARIST DOT EDU
>> Subject: Re: [ADSM-L] Disk layout for AIX
>> 
>> VGs are cheap.  Why does your AIX admin want to reduce the number of VGs?
>> 
>> David Ehresman
>> 
>> -----Original Message-----
>> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
>> Of Huebner, Andy
>> Sent: Wednesday, July 15, 2015 9:03 AM
>> To: ADSM-L AT VM.MARIST DOT EDU
>> Subject: [ADSM-L] Disk layout for AIX
>> 
>> I have an AIX admin that wants to build my new TSM server using two VGs for 
>> the database (6 file systems) and one VG for the various logs.
>> We currently have 6 VGs for the DB and 3 VGs for the logs.  Each VG contains 
>> 1 file system.
>> 
>> The DB is about 375GB and the new hardware is a P8.
>> 
>> No TSM de-dup.
>> 
>> Should I be concerned about the DB setup?
>> 
>> 
>> Andy Huebner
>> 
> 
> --
> Hello World.                                David Bronder - Systems Architect
> Segmentation Fault                                      ITS-EI, Univ. of Iowa
> Core dumped, disk trashed, quota filled, soda warm.   david-bronder AT uiowa 
> DOT edu

-- 

 Met vriendelijke groeten/Kind Regards,

Remco Post
r.post AT plcs DOT nl
+31 6 248 21 622