Re: LTO Offerings (was Library Survey)

Marc,

My experience is with the HP library, but DLT instead of LTO.  The issues
we ran into are not media or drive specific.

TSM 4.1.5.0 on AIX 4.3.3 ML 8.
HP SureStore 4/40 DLT 8000, four drives, diff SCSI

We've seen two serious problems that you'll have to watch out for:
1) Library firmware and TSM "adsmtape" driver can get out of sync.  This
causes total failure of the library in TSM.
2) The library controller cannot handle the flood of data passing through
it when it is in the middle of the SCSI chain.

Details:

1) On initial setup or our HP library, we ran into lots of problems because
the "adsmtape" driver shipped with early version of TSM 4.1 received more
data from the library firmware than it was expecting and that caused the
library to be literally unusable with TSM, despite its being listed on the
"supported devices" list and passing its own diagnostic tests.
Investigation revealed that the TSM driver had been certified with the base
release of the library firmware.  HP Tech Support gave us the secret
password to down-level the library firmware to what the driver supported
until TSM development provided an updated driver with TSM 4.1.4.  Then we
went back to the current firmware release and everything has been working
fine since.  But there is nothing that says this situation cannot recur.

2) We initially cabled our library like:
TSM Server -> lib ctlr -> drv 1 -> ... -> drv 4 -> term.
That's how all of our IBM libraries are cabled (with no problems).   But
the HP had numerous problems that usually showed up as I/O failures on
drive #1, and which continued even when the drive was replaced.  I finally
fixed the problem by cabling as:
TSM Server -> drv 4 -> ... -> drv 1 -> lib ctlr -> term.
That way the controller is at the end of the SCSI chain and the drive data
does not pass through it.  HP Tech Support thanked me for the info and
admitted that that scheme might solve several nagging problems they had
been fighting with.

Operationally, it has been a good unit since we got the problems above
solved.  We DID have to replace the picker assembly two months ago, but
over the last six months we lost the pickers in all four of our libraries
(two 3575s, a 3583, and the HP 4/40).

We use our library for creation of offsite tapes.  It is VERY handy for
that because you can open any or all of the tape magazines while the unit
is in operation.  And the "Map" function of the front panel shows the
location of every tape on a tier at one time, so in our case, I can inspect
the entire library with two button presses.  There is no comparable
function on any of our IBM libraries.

One other thing to be aware of is the synchronization between the library
and "replies" to TSM.  When you pull a tape from the HP, then close the
magazine that carries the "mail slot" (I/O slot), the library rescans the
slot and the status light is red.  If you "reply" to TSM while the libary
is in that state, TSM will accept the reply, but the library will ignore
the subsequent "move" command forcing you to pull the next tape via the
library front panel.  This is something we worked around via procedure,
saying "wait until the icon view returns to the library LCD front panel."
The odd thing is that the library continues to accept data while that light
is red.

Hope all of this helps.

Tab Trepagnier
TSM Administrator
Laitram Corporation








"Marc D. Taylor" <mdtaylor AT UIUC DOT EDU>@VM.MARIST.EDU> on 06/13/2002 
11:37:29
AM

Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

Sent by:  "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To:   ADSM-L AT VM.MARIST DOT EDU
cc:
Subject:  LTO Offerings (was Library Survey)


Hello Again,

Before this thread gets away from me, let me say a few things.

1.  From the email postings to this group it appears that the IBM LTO drive
is what most people use if they are using LTO.  I understand that IBM makes
a fine product and it gives me warm and fuzzies if I had a chance to choose
the IBM LTO drive.  Also from the postings, IBM has had it share of
teething pains in the earlier days of this technology.

2.  I guess I would really like to hear from the people on this list
(whoever you are) who chose a library with the Seagate or the HP LTO drives
and what their experiences have been, good or bad.  If no one on this list
has purchased tape libraries with Seagate or HP LTO drives then that is
telling also.

Sorry if my previous post was not focused enough.

Marc Taylor