Hi there,
HBA vendors like Emulex have support for FCP-2/FC_TAPE (i think thats it)
and have series of options on their drivers that avoid the resets to
propagate to tape devices. Of course, these options are available on the
standard drivers, not the assembers drivers (like EMC or Hitachi). They
don't support configs to their machines with drivers other than their own.
Best regards,
Bruno Madeira
____________________________
Bruno Madeira
Consultant
TERASYSTEM
Regus Torres de Lisboa
Rua Tomás da Fonseca, Torre G
1600-209 Lisboa - PORTUGAL
Phone: (+ 351) 21 723 07 28
Fax: (+351) 21 723 06 75
b.madeira AT terasystem DOT pt
www.terasystem.pt
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTMAIL.TEMPLE DOT EDU]
On
Behalf Of Mark Bradshaw (BTOpenWorld)
Sent: quarta-feira, 11 de Agosto de 2004 22:46
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: Re: [Networker] Tape SANs and dedicated HBAs
Hi Paul,
I'm impressed! Library vendors are usually pretty clueless on this issue! I
would agree with what your vendor is saying - one of the problems I have
seen relate to changes happening on the disk side when backups are running.
As I understand it when a disk is allocated, for example, a reset is sent
out to the devices which are visible on a particular HBA. A reset to a disk
(even a busy disk) isn't much of an issue. However a reset to a tape drive
causes the drive to rewind the tape currently in the drive no matter what it
is doing. The backup software that was using the tape drive has no knowledge
that this has happened and carries on writing happily to the tape and no
errors are generated.
When your customer comes to recover data, though, your customer is not going
to be too happy as the tape will have been partially overwritten and
basically useless. I've tested this with a Windows cluster acting as a
Storage Node - the end result is a tape which NetWorker can't mount as there
is no tape label at the front of the tape. It gets overwritten with data
after the reset rewinds the tape.
Minor other point is that many operating system vendors don't support this
configuration, though finding definitive documentation on this can be hard.
Both IBM and Microsoft have details on why they don't support this
configuration on their respective O/S platforms can be found on their
websites.
Cheers
Mark
> Folks,
>
> I would like to know from fellow subscribers how many folks are using
> dedicated HBAs for tape versus shared HBAs for disk and tape in SAN
> environments. I am being told by a major library vendor that despite
> having dual HBAs in hosts for redundant disk access, I need to install
> additional HBAs to access their libraries. They are suggesting two
> main
> issues:
>
>
> * Conflicting requirements in HBA set-up for disk and tape
> * Potential conflict with multipathing/failover software
>
> My proposal would not present multiple paths to a tape drive and my
> understanding of the failover software we are proposing to use is that
> it is disk specific and would not failover all I/O from one HBA to the
> other.
>
> All comments appreciated.
>
>
> Paul Esson
> Senior Support Engineer
> Redstor Limited
>
> Direct: +44 (0) 1224 595381
> Mobile: +44 (0) 7766 906514
> E-Mail: paul.esson AT redstor DOT com
> Web: www.redstor.com
>
> REDSTOR LIMITED
> Torridon House
> 73-75 Regent Quay
> Aberdeen
> UK
> AB11 5AR
>
> Disclaimer:
> The information included in this e-mail is of a confidential nature
> and is intended only for the addressee. If you are not the intended
> addressee, any disclosure, copying or distribution by you is
> prohibited and may be unlawful. Disclosure to any party other than
> the addressee, whether inadvertent or otherwise is not intended to
> waive privilege or confidentiality.
>
>
>
> --
> Note: To sign off this list, send a "signoff networker" command via
> email to listserv AT listmail.temple DOT edu or visit the list's Web site at
> http://listmail.temple.edu/archives/networker.html where you can also
> view and post messages to the list.
> =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
--
Note: To sign off this list, send a "signoff networker" command via email to
listserv AT listmail.temple DOT edu or visit the list's Web site at
http://listmail.temple.edu/archives/networker.html where you can also view
and post messages to the list.
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
--
Note: To sign off this list, send a "signoff networker" command via email
to listserv AT listmail.temple DOT edu or visit the list's Web site at
http://listmail.temple.edu/archives/networker.html where you can
also view and post messages to the list.
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
|
