So in your setup is each tape drive has both ports used, with each to a 
separate san's.
You mentioned 4 HBA's - is that 2 into each SAN?
If so, then do you have 4 RMT devices for each tape drive?

Rick



   

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Steven Harris
Sent: Wednesday, October 15, 2014 8:24 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Load balancing when you have many virtual tapes?

Rick

I have a recent set up, TSM 6.3.4.300 on AIX 7.1, LTO5s  and I too
always  thought that the atape driver did load balancing.  However I
have one port on each drive connected to one SAN and one port
connected to a second SAN and I can see what port is being used
because of which HBA the traffic goes down: in my environment I don't
have access to the switches to be able to monitor there.

All of the TSM paths were defined using devices on the same SAN as I
thought load balancing meant this would not matter.  As it turns out
the one I chose has a performance issue. Looking closer I saw that all
the traffic was going down the devices as defined in the path, and
none on the other SAN.

When I rmdev-ed the device on the SAN with the performance issue,
there was a message that the device had changed, the TSM path was
updated to the alternate device (which I did not expect) and
subsequent mounts have been on the alternate path.

HTH

Steve

Steven Harris
TSM Admin
Canberra Australia

On 14/10/2014 4:08 AM, Rhodes, Richard L. wrote:
> What kind of drive are they emulating?  Are they emulating IBM
> drives with Atape driver?  My understanding (I've been trusting
> this for years) will auto load balance across hba's.
> 
> Rick
> 
> 
> 
> -----Original Message----- From: ADSM: Dist Stor Manager
> [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of Erwann Simon Sent:
> Monday, October 13, 2014 12:36 PM To: ADSM-L AT VM.MARIST DOT EDU Subject:
> Re: Load balancing when you have many virtual tapes?
> 
> Hello Wanda,
> 
> As TSM allocates drives in order, you have to distribute drive
> between the HBAs in a round robin way (with 4 hba : drive 1 on hba
> 1, drive 2 on hba... drive 5 on hba 1 and so on). I prefer doing
> this at VTL level using mapping policy (i.e access groups on Data
> Domain).
> 
> Le 13 octobre 2014 18:28:36 CEST, "Prather, Wanda"
> <Wanda.Prather AT ICFI DOT COM> a écrit :
>> TSM 7.1.1 on AIX So I have a customer putting in a VTL, which
>> will have 96 virtual drives. Those virtual drives will be spread
>> across 4 HBA's.
>> 
>> What sort of strategies to people use to keep TSM from starting
>> a BACKUP stgpool process and picking 4 virtual drives all on the
>> same HBA? Is it dependent on the order you do your DEFINE DRIVE
>> commands? Better to set up multiple virtual libraries?
>> 
>> Any suggestions appreciated.
>> 
>> Wanda
>> 
>> 
>> Wanda Prather  |  Senior Technical Specialist  | 
>> Wanda.Prather AT icfi DOT com<mailto:Wanda.Prather AT icfi DOT com>  | 
>> www.icfi.com<http://www.icfi.com/> | 410-868-4872 (m) ICF
>> International  | 7125 Thomas Edison Dr., Suite 100, Columbia, Md 
>> |443-718-4900 (o)
> 


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