Re: [ADSM-L] Rejected posting to ADSM-L AT VM.MARIST DOT EDU

Hello,
if you use the IBM VTL TS7520, then you have the possibility to do load balancing on the FC paths. This makes really sense if you have, like in your environment, many tape drives configured.
Then it does not matter how TSM choose and use the tape drives.

The suggestion from Pierre may not work for most of the VTL, or at least it is really painful to configure it like as Pierre describes.

Here is an example:

Hope this helps - and think about the advantage of load balancing.

Mit freundlichen Grüßen / Kind regards
Josef Weingand
Senior IT Specialist

CAYE PIERRE <Pierre.Caye AT ALCATEL-LUCENT DOT FR>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

24.08.2007 11:47

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"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

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Subject	Re: [ADSM-L] How does a library choose a drive?

What type of drives are you emulating ? How many drive are simultaneously used in full charge ? What is the highest throughput you need ? Anyway, you are obliged to define 16 drives by HBA... >From my point of view, I will make the most simple choice : HBA1 : drv1, drv5, drv9, and so on HBA2 : drv2, drv6, drv10, ... HBA3 : drv3, drv7, drv11, ... HBA4 : drv4, drv8, drv12, ... > -----Message d'origine----- > De : ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] De > la part de Mcnutt, Larry E. > Envoyé : jeudi 23 août 2007 16:05 > À : ADSM-L AT VM.MARIST DOT EDU > Objet : Re: [ADSM-L] How does a library choose a drive? > > Hi Pierre, et al. > > We are in the process of adding a new VTL to our TSM server, > and we are trying to understand if there is a way to > configure the drives that will spread the I/O load across the > available fcsi ports. The AIX server has 4 4GB fibre > connections to the VTL appliance. We are emulating a Quantum > P3000 library with 64 drives. When we initially configure > the library with all 64 drives, they are divided across the 4 > fibre ports with port 1 having drive1-drive16, > port2 drive17-drive32, > port3 drive33-drive48, > port4 drive49-drive64. > > We thought this may not be an optimal setup if TSM uses a > round-robin algorithm. So, we recreated the configuration. > This time we defined 16 drives initially, which were then > spread across the 4 fibre ports with port1 drive1-drive4, > port2 drive5-drive8, > port3 drive9-drive12, > port4 drive13-drive16. > > Then we went through the process 3 more times until we had 64 > drives defined. This results in the having the drives > defined across the 4 ports as: > port1 drive1-drive4, drive17-drive20, drive33-drive36, drive49-drive52 > port2 drive5-drive8, drive21-drive24, drive37-drive40, drive53-drive56 > port3 drive9-drive12, drive25-drive28, drive41-drive44, > drive57-drive60 > port4 drive13-drive16, drive29-drive32, drive45-drive48, > drive61-drive64 > > This seems like a better configuration for a round-robin > drive assignment. It was at this point that we thought we > should try to learn how the drives are assigned. > > Thanks for any suggestions or pointers. > > Larry >