I remember once seeing on the StorageTek site, a recommendation to run the
JB robotics on its' own SCSI bus as the control commands could interfere
with normal tape or disk operation or vice versa. It was quite some time ago
that I saw it, but it was cheap enough advice to follow and seemed to
improve the reliability of the JB at the time.
Regards
Andrew McGeorge
Senior Systems Specialist
Group Technology Operations
-----Original Message-----
From: George Sinclair [mailto:George.Sinclair AT NOAA DOT GOV]
Sent: 10 December 2003 12:39PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: Re: [Networker] Running the library picker/changer on its own SCSI
channel?
So it sounds like you're saying that performance was degraded when you had
all the drives and the picker sharing the same channel but when you put the
picker on a separate card/channel the performance increased?
We discovered that we were in fact running both libraries on the same SCSI
bus! I think we must have been under the impression that we were running
each library on its own separate bus because each was on its own card/PCI
slot, but in fact having two separate PCI slots does not infer two separate
buses. We had never considered this before. We moved the storage node to a
different server where each library now has its own dedicated bus. However,
each library is still running on one and only one card. So in the case of
the ATL library, we have two SDLT drives and the picker sharing channel A on
one dual-channel Adaptec card on one bus, and the Storagetek (it has 4 LTO
drives; two drives on channel A and two drives and picker on channel B) uses
the second dual channel card on the other bus. So at least we have the two
libraries now on separate buses. We're going to see if this makes a
difference. We don't have a third card, but we will be buying one. Once we
have the third card, we can then move the Storagetek's picker to its own
card on a third bus. We're not using channel B, though, on the card that the
ATL is using, so we could move the ATL picker to that channel and have the
two SDLT drives continue using channel A. Guess that couldn't hurt, but
we'll need to re-cable the libraries for any these options.
Do you think we need to have the pickers on their own channel or actually
have them on their own bus apart from the buses that the drives are using?
I appreciate your feedback. Will keep the list updated on our findings. I'm
hoping that having the libraries on separate buses will help, but we can go
finer grade by moving the picker to yet another actual bus. I guess we could
have the ATL library's picker on a fourth bus also, and maybe even split up
the drives on the Storagetek so no more than two share the same bus. That
would require a total of 5 buses and 5 cards, but not sure that that will be
necessary. It seems like performance could only be better, but maybe we're
not pushing the drives enough to warrant that?
Will keep everyone informed as the events unfold.
Thanks again.
George
Olaf Zaplinski wrote:
>
> Hi George,
>
> I can not tell much but my own Storagetek experience, here we have an
> L700e.
>
> When the jukebox is connected to the same HBA (Adaptec, 160 MB/s
> capable) as our two tapes on the second SCSI chain, then the 1st tape
> is logged on as 40 MB/s + 8 bit, the second one as 80 MB/s + 16 bit.
> The latter one is correct. When I connect only those two drives to the
> Adaptec, everything is fine.
>
> This is why we drive the JB device with its own host adapter (Adaptec)
> and the two SCSI tape drive chains on others (LSI 53c1030). The L700's
> firmware is brand new, we had it serviced last week.
>
> So I think it is better to spend some money for a host adapter that is
> only connected to the jukebox/the picker. Since there is no heavy SCSI
> traffic, I guess that any 32 bit PCI card that can do LVD would do the
> job.
>
> Regards
> Olaf
>
> --
> 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.
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
========================================================================================
This email message and attachments are confidential to our organisation and
subject to legal privilege. If you have received this email in error, please
advise the sender immediately and destroy the message and any attachments. If
you are not the intended recipient you are notified that any use, distribution,
amendment, copying or any action taken or omitted to be taken in reliance of
this message or attachments is prohibited. You can read our Privacy Policy
here: <http://www.asbbank.co.nz/privacystatement.stm>
=========================================================================================
--
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.
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
|
