For the below to work, the book says that the devices have to be directly
attached to the HBA's. Has anyone tried configuring alternate path
support for SAN attached 3590-H's? The book says that it is not
supported.
> A recent version of Atape is required for dual path support. We use
> Atape 8.3.1.0.
>
> You also need to enable alternative pathing support on the rmt device which,
> I think is set to off by default:
> i.e. chdev -l <device> -a alt_pathing=yes
> Then when you make the devices available to the host you will notice
> twice the number of drives. If you look at the device attributes with
> lsattr -El rmtx
> you will notice the location code xx-xx-xx-ALT or PRI ,
> the primary device value and the WWN. The latter will be 0xnnnnnnnnnn4nnnnn
> for
> the primary device and 0xnnnnnnnnnn8nnnnn for the alternative device.
> These allow you to 'pair' up the devices.
>
> If you have more than 3 or 4 tape devices I would recommend you employ a
> naming
> convention to the devices to make these pairs more transparent, by renaming
> them
> after cfgmgr has brought them into the system.
> Thus, we do a rmdev -l <rmtX> ; chdev -l <rmtX> -a new_name=rmtY
> such that the secondary / Alternative device name is 50 greater than primary
> device name - i.e:
> rmt2 => rmt52
> rmt3 => rmt53 and so on.
>
> Note that errpt will log errors against both device names, depending on which
> interface the drive was being accessed when the error occurred.
>
> Finally, our experience tallies with Steve Harris' - failover is seamless
> - we pulled the active cable from a drive while backing up (test !) client
> data to tape and the backup carried on over the other path. TSM didn't blink.
> We subsequently audited the tape and all was OK.
>
> Regards
> -------------------------------------------------------------------
> Ian Smith
> Oxford University Computing Services, Oxford, UK.
> -------------------------------------------------------------------
>
>
>
>
>
> ~>Mime-Version: 1.0
> ~>Content-Transfer-Encoding: quoted-printable
> ~>Content-Disposition: inline
> ~>Date: Tue, 18 Nov 2003 08:48:41 +1000
> ~>From: Steve Harris <Steve_Harris AT HEALTH.QLD.GOV DOT AU>
> ~>Subject: Re: 2 fibre interfaces per drive
> ~>To: ADSM-L AT VM.MARIST DOT EDU
> ~>X-Oxmail-Spam-Status: score=0.0 tests=
> ~>X-Oxmail-Spam-Level:
> ~>
> ~>Joni,
> ~>
> ~>Later versions of the Atape driver support dual pathing and failover.
> ~>Once set up, AIX defines two RMTn drives for each physical drive, one with a
> device path ending in -PRI and the other in -ALT.
> ~>
> ~>As I understand it rudimentary load balancing is done - when the tape is
> opened, the least busy path is used.
> ~>
> ~>Failover is also neat. I was running the tapeutil test command and
> deliberately varied off the adapter in use. The io just picked up where it
> left
> off on the other path.
> ~>
> ~>See the Totalstorage Tape Installation and Users Guide, available from
> ftp://service.boulder.ibm.com for details
> ~>
> ~>Steve Harris
> ~>AIX and TSM Admin
> ~>Queensland Health, Brisbane Australia
> ~>
> ~>>>> Julian.Armendariz AT HBFULLER DOT COM 18/11/2003 7:13:13 >>>
> ~>IBM 3590 and 3592 drives have 2 fibre interfaces. I am unsure how to
> ~>manage the multipathing yet, but we are going to look at configuring our
> ~>3590H drives that way next year to eliminate that single point of
> ~>failure. Our TSM server is running AIX 5.2ML2 which is connected to a
> ~>3494 library with 4 3590H drives which are connected to a Brocade 2800.
> ~>
> ~>
> ~>Julian Armendariz
> ~>System Engineer - UNIX
> ~>H.B. Fuller
> ~>(651) 236-4043
> ~>
> ~>
> ~>
> ~>>>> joni.moyer AT HIGHMARK DOT COM 11/17/03 12:48PM >>>
> ~>Hi everyone!
> ~>
> ~>We are in the process of formulating an AIX environment instead of our
> ~>current MVS TSM environment. We would have 2 TSM servers (one being
> ~>the
> ~>library manager) with 2 directors, 8 lan-free clients and 24 tape
> ~>drives,
> ~>which we hope to share between the 2 TSM servers. We would like to
> ~>have 2
> ~>fibre interfaces per drive in order to eliminate a single point of
> ~>failure.
> ~>My question is, how does TSM know which path it is using to the drive
> ~>and
> ~>how does it know that one of the paths to an individual drive is
> ~>already in
> ~>use? Is there software out there to manage this or is it done through
> ~>the
> ~>hardware configuration? If anyone has any suggestions I would
> ~>appreciate
> ~>it! Thanks!
> ~>
> ~>
> ~>***************************************************************
> ~>Joni Moyer
> ~>Highmark
> ~>Storage Systems
> ~>Work:(717)302-6603 **New as of 11/1/03
> ~>Fax:(717)302-5974
> ~>joni.moyer AT highmark DOT com
> ~>***************************************************************
> ~>
> ~>
> ~>
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Steve Roder, University at Buffalo
HOD Service Coordinator
VM Systems Programmer
UNIX Systems Administrator (Solaris and AIX)
TSM/ADSM Administrator
UB DNS Team
(spr AT buffalo DOT edu | (716)645-3564)
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