Hi, George,
Due to budget-related compromises, we have a data zone with mixed LTO-3
and LTO-2 drives, LTO-2 tapes and a single tape pool. I don't watch this
particular data zone closely enough that I'm able to swear we've had
data sets span from an LTO-2 tape to an LTO-3 or the reverse, but the
server has been in service for a year and a half without any
backup/restore issues (maintenance issues on ancient LTO-2 drives and an
antique jukebox are another matter). I would imagine that data set
spanning from one tape type to another is a rather common event in this
data zone and we haven't detected any problems.
Conrad
-----Original Message-----
From: George Sinclair [mailto:George.Sinclair AT NOAA DOT GOV]
Sent: Friday, April 30, 2010 11:13 AM
Subject: Re: Using LTO3 in LTO4 drives?
Conrad Macina wrote:
> An LTO-series drive will read and write its own generation of tapes
and one
> generation back. It will read two generations back. So an LTO-4 drive
will
> read and write LTO-3 media and will read LTO-2. It will not work at
all with
> LTO-1 media. That's in the LTO spec, and is borne out by my
experience.
I guess my main concern was not that the LTO-4 drives won't read/write
to an LTO-3, but that maybe a backup that spans from an LTO-3 to an
LTO-4 or vice versa could cause issues? I'm thinking not, but thought
I'd ask if anyone had seen anything weird like that. We are using LTO-4
media, but I have some LTO-3 media that I'd like to recycle and keep
using.
>
> When you write to a one-generation-back tape you get none of the
capacity
> benefit. A 400 GB (native) LTO-3 tape will still hold 400 GB when
written in
> an LTO-4 drive. I haven't done any rigorous benchmarks, but it appears
that
> you get about 80% of the speed benefit.
>
> You can't put a higher-generation tape into a lower-generation drive.
It
> will eject right away, sort of like a cleaning tape, only faster. And
> without any benefit to the drive. And NetWorker and the library will
become
> very, very confused.
>
> Conrad Macina
> Pfizer, Inc.
>
>
>
> On Fri, 30 Apr 2010 08:29:57 +0300, Yaron Zabary
<yaron AT ARISTO.TAU.AC DOT IL> wrote:
>
>> I had an LTO-2 library with some 400 LTO-2 cartridges. When I
>> replaced the library with an LTO-3 library (Overland NEO8000 with
four
>> HP LTO-3 drives), I simply moved all 400 cartridges to the new
library
>> and it just worked. Then, within a few years I replaced the LTO-2
media
>> with LTO-3 media and all worked with no apparent problem. Recently,
when
>> the drives were upgraded to LTO-4, it just worked (I only had to
remove
>> the last LTO-2 cartridges that were still in). Now I have LTO-4
drives
>> and most of the cartridges are still LTO-3. Naturally, I will start
>> replacing the media with LTO-4 as the need arises.
>>
>> George Sinclair wrote:
>>> Is it a problem to recycle older LTO-3 media in LTO-4 drives and
label
>>> these into the same tape pool? This is in an all LTO-4 drive tape
library.
>>>
>>> I've had no issues reading from LTO3 tapes in the LTO4 drives, and
they
>>> are supposed to be backward write compatible (haven't tried that
yet),
>>> but will NW span mixed tapes properly, assuming all drives are LTO4?
>>>
>>> George
>>>
>> --
>>
>> -- Yaron.
>>
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--
George Sinclair
Voice: (301) 713-3284 x210
- The preceding message is personal and does not reflect any official or
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