Tapes?

Paul wrote:

In article ,
says...
correct. I backup to an SDLT over FastEthernet without
shoe-shining. SDLT has the ability to slow down to compensate for a
slow data stream.


Really? Are you sure you're not just using the cache and shoeshining a
_little_ bit? After all, SDLT 220 is only 11 MB/s (almost feasible with
FastE), and SDLT 320 isn't that much faster at 16 MBs.

I had heard that Quantum was calling it "Variable Speed Recording" or
VSR and that they started using it with the DLT8000 but I just did a
search and it is unclear whether they actually implemented it or just
talked about it.

In any case, whether it is a larger buffer, or it really is VSR, I don't
get shoe-shining using FastEthernet. I was planning on using Amanda to
stage the data first but I found that I didn't have to and I could just
use my regular scripts that use tar and dd.

Plus doesn't match up with the FUD put out by the LTO vendors, which I
don't put much stock in, but outright lies are pretty rare.

I don't put much stock in the marketing tables either, especially from
competing companies.

Steve

In article ,
Paul wrote:
Quantum's product line seems to jive with this thinking. They offer the
VS and DLT-1 series which has the lower drive speed for just these
environments.

DLT1 is just a cheaper DLT-8000-class design that doesn't bother being
compatible with DLT-8000 and earlier.

They're _still_ selling DLT8000, which matches up
perfectly to real-world FastE.

It's also compatible with people's existing data and infrastructure. Go
to DLT1 or SDLT and you lose access to your data.

--
I've seen things you people can't imagine. Chimneysweeps on fire over the roofs
of London. I've watched kite-strings glitter in the sun at Hyde Park Gate. All
these things will be lost in time, like chalk-paintings in the rain. `-_-'
Time for your nap. | Peter da Silva | Har du kramat din varg, idag? 'U`

In article , Steve Cousins writes
In article ,
says...
correct. I backup to an SDLT over FastEthernet without
shoe-shining. SDLT has the ability to slow down to compensate for a
slow data stream.


Really? Are you sure you're not just using the cache and shoeshining a
_little_ bit? After all, SDLT 220 is only 11 MB/s (almost feasible with
FastE), and SDLT 320 isn't that much faster at 16 MBs.

I had heard that Quantum was calling it "Variable Speed Recording" or
VSR and that they started using it with the DLT8000 but I just did a
search and it is unclear whether they actually implemented it or just
talked about it.

In any case, whether it is a larger buffer, or it really is VSR, I don't
get shoe-shining using FastEthernet. I was planning on using Amanda to
stage the data first but I found that I didn't have to and I could just
use my regular scripts that use tar and dd.

On the DLT7000 there was a mode which avoided the shoe-shine during
write, but wasted tape capacity. If the host was too slow, it rewrote
the same blocks from the buffer until new data was available.

I haven't worked much with DLT8000 or anything newer, so I don't know if
the VSR you refer to is something better.
--
Jonathan Griffitts
AnyWare Engineering Boulder, CO, USA

In article ,
says...
In any case, whether it is a larger buffer, or it really is VSR, I don't
get shoe-shining using FastEthernet. I was planning on using Amanda to
stage the data first but I found that I didn't have to and I could just
use my regular scripts that use tar and dd.


What flavor of SDLT are you using? 220, 320, or 600? I would very
surprised to find that you were using SDLT 600 in a FastE environment
and not shoeshining.

Variable speed recording is referred to in the sales documentation for
some DLT 8000 drives, but I've seen it mostly in Exabyte docs...

There's a great article here http://www.open-mag.com/features/Vol_
90/sdlt/sdlt.htm. It's about how SDLT 600 outperforms LTO-2, and
covers (albeit briefly) the difference between DLT's Digital Data Rate
Agent and LTO's Adaptive Tape Speed, but unfortunately it only covered
the two schemes' handling of randomly introduced incompressible data
into a compressible data stream. Their testing covered only
environments that could effectively stream enough data to the drive in
order to keep it saturated.

HP has good specs on their web site for the SDLT 320 and LTO-2 drives
they sell. Nothing in the specification about anything that looks like
data rate matching. And they sell a lot of DLT, so their specifications
are salesish at all; I believe that if data rate matching (whatever
Quantum would call it) was offering the SDLT line, they would say so.

--paul

"Adrian 'Dagurashibanipal' von Bidder" wrote in
message ...
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Clinging to sanity, Rob Turk mumbled in his beard:

Have you considered the 1U packet loader from Exabyte? VXA-2 drive[...]

(First: thanks to all the comments. Very helpful for somebody like me new
to
tape/backup set up questions)

I've had a short look at the VXA drives, but I'm not sure if I like it -
LTO
and DLT have multiple vendors making drives (not sure about AIT), so there
are fallback scenarious if one of them goes down the drain. Does anybody
else make VXA drives? (Yes, Exabyte has been around for a long time, so
there's a chance that they will stay around. But you just never know...)

Or is inter-vendor compatibility a pipe dream anyway?

Else, the loader you mentioned seems like a good deal to my untrained eye.

greets
- -- vbi

You do have a point about single-vendor. VXA is currently only produced by
Exabyte. LTO is HP, IBM and Certance (former Seagate). (S)DLT is produced by
Quantum (shakey right now) and Tandberg.

There's always a risk of a vendor disappearing, but that doesn't mean the
products are gone immediately too. As a sanity check, just look around on
auction sites to see how many old Conner, WangDAT, DEC TK50 and OnStream
drives are still being sold. Some of these have been gone for many years,
but their products are still available if you really need them. Same goes
for older Exabyte products. Even 1990 vintage EXB-8200 drives still show up.

My suggestion would be to get what fits your current needs. Whatever you
select will be adequate for the next 3 to 5 years. In that timeframe there
will always be product available. When/if a vendor really goes away, select
the next thing by then. Buy/rent/borrow a spare if you need to restore from
older media, and migrate to your next vendor of choise.

By the way, Exabyte has no intention of disappearing ;-)

Rob

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Clinging to sanity, Rob Turk mumbled in his beard:
[...]

comments appreciated, thanks. (also goes to the others responding in this
thread, of course!)

greetings
- -- vbi

- --
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Paul wrote:

What flavor of SDLT are you using? 220, 320, or 600? I would very
surprised to find that you were using SDLT 600 in a FastE environment
and not shoeshining.

It is the 220 so maybe I'm just squeaking by with Fast Ethernet. By the
time I upgrade the drive the whole group of machines will be on GigE so
hopefully that will suffice. Everything in the group is already on GigE
except the backup machine come to think of it.

I think I want to wait for the next generation of drives before I
upgrade but I'm not sure when that will be. I'm thinking that LTO-3
will come out much before the SDLT 1200 drives so I'm leaning on doing
that. Our data storage needs have ballooned over the last year so
managing it all with the SDLT 220 is starting to be a bit of a problem.

One last time and then I'll stop asking: Anyone have any idea when LTO-3
is realistically expected to be available?

Also, is there another, higher end drive that has a higher capacity
without going to a library? Are the 9940 drives expected to have higher
capacity any time soon?

Thanks,

Steve

I have an exabyte mammouth m2 and I love this drive. It is very fast. I can
backup a remote server at about 600 to 660 MB/min. If I run a local restore,
I get about 750 MB/Min.

This will backup 80 gb uncompressed and 160 gb compressed. The media is
between $80 to $90 each.