SUM: DLT auto loader reliability?

From: John Miller <John.Miller_at_jcu.edu.au>
Date: Mon, 4 Nov 1996 22:06:58 +1000 (EST)

Thanks to all who took the time to respond.

The consensus is that the TZ885 Digital Linear Tape auto loader and its
predecessors in 7 tape cartridge guises are excellent as far as
reliability is concerned. The upgradability of the drives while retaining
the auto loading mechanics received general approval as well.

Tom Webster <webster_at_europa.mdc.com> alerts us to a gotcha regarding the
licensing of NSR from V4.2a which he reports requires a Tier One Jukebox
option evne if you only use it as a sequential auto loader.

My original request and the interesting bits of the replies follow.
+---------------------------------------------------------------------+
| John Miller | Internet Mail - John.Miller_at_jcu.edu.au |
| Computer Centre |
| James Cook University of North Queensland | Phone: +61 77 815447 |
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+---------------------------------------------------------------------+

On Fri, 1 Nov 1996, John Miller wrote:

>
> We are consdiering replacing our Exabyte backup technology with DLT units
> in the near future owing what are becoming frequent failures of our
> exabyte stacker drives of late.
>
> We are considering two options really, two TZ88 (20/40 GB single drive
> manual load) units,
>
> versus
>
> a single TZ885 (100/200Gb single drive 5 tape auto load) unit.
>
> Is there any reason to be suspicious of the reliability of the mechanical
> auto loader device which would sway our thinking concerning the trade-off
> between greater total data capacity and greater backup throughput?
>
> +---------------------------------------------------------------------+
> | John Miller | Internet Mail - John.Miller_at_jcu.edu.au |
> | Computer Centre |
> | James Cook University of North Queensland | Phone: +61 77 815447 |
> | Townsville, 4811, AUSTRALIA | Fax: +61 77 815230 |
> +---------------------------------------------------------------------+
>
>

********************
From: Jo Knox <fxjwk_at_aurora.alaska.edu>
We have a rather older TF857 subsequently upgraded to TZ877. This uses a
TZ87 (10/20 GB). I really love this drive; the 7 tape autoloader has
broken once in the several years we've had it (broken gear, fixed the same
day), and failed to load a tape once, that I can recall. Coming from 9
track tapes, this thing is a dream! We've been able to make our machine
room pretty much a lights out operation; I need to go by there once per
week and change tapes!
Jo Knox
University of Alaska Fairbanks
Division of Computing & Communications


********************
From: "Alan Rollow - Dr. File System's Home for Wayward Inodes."
     <alan_at_nabeth.cxo.dec.com>

None that I've seen. I wrote the Digital UNIX side of the Media
Robot Utility that should be included with the TZ885 to control
the robot and I've never had our TZ885 fail. We also have some
older TZ875s and they have also been fairly reliable. We had one
bad one, but I think it bad from the start.


********************
From: Tom Webster <webster_at_europa.mdc.com>
To: John.Miller_at_jcu.edu.au

We have a number of TZ877's here (TZ85 drives with a seven slot robot) and
they have been very reliable with NSR or acting as autoloaders (VAX/VMS 5.x).

The robot setup has gotten much simpler with NSR 4.2, if you are going to be
using NSR and are running at least 3.2c give upgrading some thought. If you are
going to be using it as a juke, you are also going to need to load up the
CAM software. Under 3.2x we had to load both sets to get it to work reliably
(even though we don't have an optical drive). (BTW - There are conflicts
between the CAM software and the Multi-Media stuff for DU, you are going to
have to jettison the MM stuff.)

Other than some crankyness with the CAM software the TZ877s have been a joy.
So far, after a year of heavy use with NSR, I haven't had any mechanical
problems.

The only downside I can think of for the TZ8xx family is that with NSR 4.2a,
you need to pay for a Tier-1 Juke license -- even if you are using it as an
autoloader. (This is a new thing with the 4.2a release, you used to be
able to use them as dumb changers for free.)

In regards to the TZ88's: We have four of them in our TL812. The biggest
problem to date is the media. We were lucky and got enough to stock the
library when we bought it. Others on this list are claiming that there
is a 6-8mo waiting list for tapes. The media is also hellishly expensive.

Hope my ramblngs helped,

Tom

--
+--------------------------------+------------------------------+
| Tom Webster                    | "Funny, I've never seen it   |
| SysAdmin MDA-SSD ISS-IS-HB-S&O | do THAT before...."          |
| webster_at_ssdpdc.mdc.com         | - Any user support person    |
+--------------------------------+------------------------------+
|   Unless clearly stated otherwise all opinions are my own.    |
+---------------------------------------------------------------+
********************
From: Huw Davies <H.Davies_at_latrobe.edu.au>
To: John Miller <John.Miller_at_jcu.edu.au>
Subject: Re: DLT auto loader reliability?
We've had a TZ877 tape stacker in production use here at La Trobe for two
years. We've only ever logged on call on the device and that was to replace
the drive not the stacker. As far as I'm concerned it's one of the most
reliable devices we have (far more reliable than the systems it's attached to). 
In the worst case scenario (restoring system after failure) should the
stacker fail I can't see any reason why the tapes couldn't be inserted by
hand - although I should point out that I haven't tried this myself :-)
 Huw Davies                      | e-mail: Huw.Davies_at_latrobe.edu.au
 Information Technology Services | Phone: +61 3 9479 1550  Fax: +61 3 9479 1999
 La Trobe University             | "My Alfas keep me poor in a monetary
 Melbourne Australia 3083        | sense, but rich in so many other ways"
********************
From: Sheila Hollenbaugh <shollen_at_valhalla.cs.wright.edu>
To: John Miller <John.Miller_at_jcu.edu.au>
Subject: Re: DLT auto loader reliability?
We have had the auto loader for some years now, have even upgraded the tape
drive associated with it, and have not had any problems with it at all.
--Sheila
********************
From: "Steve.Woodward" <Steve.Woodward_at_pscmail.ps.net>
     
     We have had 3 TZ875's for about 18 months.  Two of them have had 
     problems, about 2 service calls each.  All problems have been with the 
     embedded tape drives, not the loader hardware, so I believe we would 
     have had the problems even if they where TZ87's.  That said, I like 
     the TZ875's and would recommend them.
     
     Regards,
     Steve Woodward
     woody_at_ps.net
********************
From: Thomas Marcoulier <marcoulier_at_cric.com>
I have been using the DLT autoloader (7 cartridge model) for 3-4 years now
with NO real problems (one service call).  I have used them on both VMS and
DEC UNIX. I personally like them alot.  We currently have 2 DLT 2700 (10/20
GB) and 2 DLT 4700 (20/40GB).
Tom Marcoulier
********************
From: Todd Acheson <acheson_at_oak.cats.ohiou.edu>
I have been running the 2 DEC DLT stackers for 1.4 
years now with only a single failure that was 
transient.
I have a stacker per machine on 2 servers.
I run a cartridge per night and swap the stack once a 
week.  What a relief not to have to screw with 
replacing tapes by hand on some schedule.
I just pull the stack on Monday and move it to offsite 
storage and put in a stack returned from offsite.
********************
From: "Edward C. Bailey" <ed_at_pigdog.niehs.nih.gov>
Reply-To: bailey_at_niehs.nih.gov
We've been doing backups seven days a week with a TZ877 (a seven-slot
predecessor of the TZ885) for over a year, and have only had one loading
problem with it.
Having been a VAX hack from way back, I remember the horrible TK50 drives,
and prepared myself for regular sessions extracting stuck tapes, replacing
leaders, etc.  But we've had no problems like that.
                            Hope this helps,
                                    Ed
-- 
Ed Bailey, Information Systems and Networks
(contracted to: National Institute of Environmental Health Sciences)
2327 Englert Drive.
Suite 200
Durham, NC 27713
                              
 Internet: bailey_at_niehs.nih.gov
   BITnet: BAILEY_at_NIEHS.BITNET 
    Voice: (919)361-9422, extension 239
      FAX: (919)544-6642
********************
From: John Nebel <nebel_at_athena.csdco.com>
I bought one of the first RA867 (6gb x 7 tapes in a stand-alone cab) - later 
eviscerated it and made it a TZ877 and put it in a Storage 
Works box.  Never had any trouble with it at all.  A second drive which 
started as a TZ877  is now a TZ887 and is also fine.  The upgrability of
those machines is handy - keep the loader, replace the drive.
John Nebel 

Received on Mon Nov 04 1996 - 14:14:06 NZDT