Thanks to John.
I am attaching his reply.
Regards,
vsp
>From: John P Speno <speno_at_isc.upenn.edu>
>To: "Prasad V.S." <vspra_at_hotmail.com>
>Subject: Re: Followup Question: Multipathing in Tru64 Unix.
>Date: Mon, 2 Apr 2001 09:41:18 -0400
>
>See my summary from January 10th of this year in the archives. Subject
>was " SUMMARY: Fun with fibre-channel HBAs"
>
>You can find links to archives on www.tru64.org.
>
>Quick answer is that an EVM message is generated when the connection
>to a device is reduced or increased. You can filter them and have them
>mailed to you. You just need to invest some time to learn how to work
>with EVM. It's probably worth it.
>
>good luck.
>
>On Mon, Apr 02, 2001 at 01:10:16PM +0000, Prasad V.S. wrote:
> > Hi All,
> >
> > This is the follow-up question for multipathing support on Tru64
> > Unix. As a first step in analysing the multi-pathing on Tru64 Unix, I
>just
> > wanted to find out how the administrator will come to know that there is
>a
> > path failure in non-multipathing setup.
> > I used sysman to monitor the path failure for the juke box connected to
>my
> > system.
> >
> > # sysman -menu "View events"
> > The following is the error file correspondinig to this.
> >
> > *****************************************************************
> > ======================= Binary Error Log event =======================
> > EVM event name: sys.unix.binlog.hw.scsi
> >
> > Binary error log events are posted through the binlogd daemon, and
> > stored in the binary error log file, /var/adm/binary.errlog. This
> > event is used to report all SCSI device errors, including disk,
> > tape, HSZ raid events, and adapter errors.
> >
> > ======================================================================
> >
> > Formatted Message:
> > SCSI event
> >
> > Event Data Items:
> > Event Name : sys.unix.binlog.hw.scsi
> > Priority : 700
> > Timestamp : 30-Mar-2001 16:19:01
> > Host IP address : 20.240.20.220
> > Host Name : Unix51
> > Format : SCSI event
> > Reference : cat:evmexp.cat:300
> >
> > Variable Items:
> > subid_class (INT32) = 199
> > subid_num (INT32) = 1
> > subid_unit_num (INT32) = 89
> > subid_type (INT32) = 34
> > binlog_event (OPAQUE) = [OPAQUE VALUE: 1096 bytes]
> > ============================ Translation =============================
> > Sequence number of error: 146
> > Time of error entry: 30-Mar-2001 16:19:01
> > Host name: Unix51
> >
> > SCSI CAM ERROR PACKET
> > Controller type: DISK
> > SCSI device class: DEC SIM
> > Bus Number: 1
> > Target number: 3
> > Lun Number: 1
> >
> > Name of routine that logged the event: scsi_perform_timeout
> > Event information: timeout on disconnected request
> >
> > ############### Entry End ###############
> >
> > Event information: Active CCB at time of error
> >
> > ############### Entry End ###############
> >
> > ======================================================================
> > *****************************************************************
> >
> > Here the SCSI driver returned as error "SCSI CAM ERROR PACKET".
> > My question is that in a mulipathing environment, how the administrator
> > determines/monitors the path failure and how does the alternate path
>chosen?
> > Does administrator's presence is required in the identification of the
> > alternate path or is it done by controller/driver?
> >
> > Cheers,
> >
> > vsp
> >
> > >From: "Prasad V.S." <vspra_at_hotmail.com>
> > >To: tru64-unix-managers_at_ornl.gov
> > >Subject: Summary: Multipathing in Tru64 Unix.
> > >Date: Wed, 21 Mar 2001 11:09:56
> > >
> > >Thanks to both Mr.Alen (alan_at_nabeth.cxo.dec.com ) and Dr.Thomas
> > >(Dr.Thomas.Blinn_at_Compaq.com)
> > >
> > >Here is the summary.
> > >
> > >Mr.Alan's
> > >
> > >Multipathing is handled in the SCSI driver.
> > >Unless explicit path selection was a required feature for the first
> > >release, it may be sometime for a API interface that allows path
>selection
> > >is available, if ever.
> > >
> > >Dr.Thomas's
> > >
> > >Not supported prior to V5.0, generally will not work correctly in V4.x.
> > >
> > >There are no APIs. There is no actual multipathing for storage for
> > >performance, all I/O is done through one path (to a given device) as
>long
> > >as the path works.
> > >
> > >Once again thanks,
> > >
> > >vsp.
> > >
> > >Original question
> > >
> > > >>Hi Managers,
> > >
> > > >> Do we have any specific APIs/layer interface for the >>multipathing
>in
> > >Tru64 Unix
> > > >>(Any version). (i.e For issuing IO's to storage LUN's through
> > > >>different paths,
> > > >>which increases the availability of storage in case of failure in
>any
> > > >>one path.
> > >
> > > >> And also I am interested to know how the Load Balancing, Path
> > > >>Verification, and
> > > >>Failover capability are done internally. Any pointers on this are
> > > >>really
> > > >>helpful.
> > >
> > > >>Many advanced thanks,
> > >
> > > >>Cheers,
> > >
> > > >>vsp.
> > >
> > >
> > >
> > >
> >
> >
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Received on Fri Apr 06 2001 - 10:56:52 NZST