Networker

Re: [Networker] SCSI problems -- How many drives to a bus?

2004-01-12 11:54:42
Subject: Re: [Networker] SCSI problems -- How many drives to a bus?
From: George Lavrov <glavrov AT MAIL DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Mon, 12 Jan 2004 08:38:56 -0800
Have you tried a different SCSI terminators? According my local contact at
STK, a while ago STK released number of terminators which had problems...
I have sold SCSI problems (LTO drive transfer rate)  twice (on Windows) with
STK L80 and L40 for the last 6 month simply by replacing STK  terminators
with a regular type LVD/SE...

Cheers,
Gueorgui (George) Lavrov, MCSE
glavrov AT mail DOT com



-----Original Message-----
From: George Sinclair [mailto:George.Sinclair AT NOAA DOT GOV]
Sent: Friday, January 09, 2004 9:36 AM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: SCSI problems -- How many drives to a bus?

Hi,

We have a Storagetek L80 tape library with 4 LTO drives. We've been seeing a
lot of SCSI problems on the host. Host is a storage node running RedHat
Linux. I end up rebooting this host about once a week because the
/etc/LGTOuscsi/inquire utility fails to see the picker device. This is
really annoying. We finally moved the storage node to another, more powerful
Linux box with more buses, etc. Same problem there!!! The first clue is the
"read open error, Device or resource busy" message that appears next to the
affected device in the devices section of the nwadmin window. Often, a
backup will be running when the host loses communication to the picker.

We have the robot on its own separate bus and all 4 drives share a bus.
Max sessions per device is set to 5. We're running 6.1.1 under Solaris
primary server. Should also note that we do have an ATL SDLT tape library
running on there, too. Its picker, and two drives all share same bus, but
this bus is its boss and does not share anything with the L80.
So, we have three Adpactec cards: one for ATL, one for L80 picker and one
for L80 LTO drives (dual channel Adapctec cards).

I'm wondering if we have too many LTO drives on the bus? Could this cause
these SCSI problems? Maybe better to have no more than two drives per bus?
Someone suggested that we get the picker on its own bus which we recently
did but that didn't fix it. I'm beginning to think that there's something
wrong with the Storage Tek library and maybe it's time to have Storage Tek
come look at it. Maybe we should get a temp license for another storage node
and move the ATL over there so we only have one library on this host? Guess
it would be easier to troubleshoot, but seems silly to have to do that. NO
reason we should not be able to run two libraries, and the thing is is that
the ATL libary never gives us any problems. I never see these "read open
error ..." messages on there.
Hmm ....

Any thoughts?

Thanks.

George

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