This was just printed in an AS/400 newsletter I get about the LTO tape
drives. I thought you might find it interesting:
Date: Fri, 21 Apr 2000 16:49:21 -0700
From: tbeauchamp AT midrangecomputing DOT com (Terri Beauchamp)
To: "'mmu AT midrangecomputing DOT com'" <mmu AT midrangecomputing DOT com>
Subject: Monday Morning Update 04/24/00
Message-ID: <01BFABB1.8B5F4160.tbeauchamp AT midrangecomputing DOT com>
A Midrange Computing Publication
April 24, 2000
IBM is putting the final touches on a long-awaited line of
tape drives and libraries that employ tape technology that
Big Blue has jointly developed with Seagate Technology and
Hewlett-Packard. Like IBM, Seagate and HP generate a
considerable amount of revenue from selling low-end and
midrange tape drives. Back in November 1997, the three
vendors ganged up to develop a new tape technology called
Linear Tape Open (LTO) which they all agreed to develop and
support. In spring 1998, the LTO designers published the
LTO standard specification, and the compliance verification
process for the spec was released in May 1999. LTO now has
25 licensees, one of them being, of course, Big Blue. The
tape libraries that IBM will announce for the midrange
later this summer go by the code name "Anaconda," and will
be sold under the StorageSmart brand name. IBM intends to
aim the Anaconda drives and libraries at the UNIX and
Microsoft Windows NT/2K server markets; it is unclear if it
will support OS/400 or not, but I am of the opinion that it should.
There are actually two flavors of LTO drives. The high-
capacity implementation of the drive is called Ultrium LTO,
and the high-speed implementation is called Accelis LTO.
Although they both use 5.25-inch cartridge tapes that
resemble IBM's 3480/3490 cartridges, they differ in that
the LTO units store data in a digital format rather than an
analog format. Under the original LTO drive specs published
last year, the Ultrium units spread data across 384 data
tracks using either 4 or 8 channel head geometry. The 384
tracks are split into four 96-track bands, much as disk
drive platters are divided up into sectors to facilitate
random access. The initial units will have native tape
capacities of 10 GB, 30 GB, 50 GB, and 100 GB. It would
take changing the number of tracks that can be activated, or
shortening the length of the cartridge supported by the
Ultrium drive--or both. But it looks like the 100 GB
flagship Ultrium drive will be an 8-channel, four 96-track
band unit capable of pushing data at about 15 MB per second
in uncompressed mode. (The original specs called for data
transfer rates of between 10 MB per second to 20 MB per
second.) Each successive Ultrium generation--there are
three more slated over the next couple of years--calls for a
doubling of native capacity and native data transfer rates
on an LTO tape drive. IBM, HP, and Seagate will use a mix
of recording and tape technologies to accomplish this growth.
The fourth-generation Ultriums will be able to store 800 GB
of uncompressed capacity on a single tape and move data at
about 120 MB per second. That data rate could go as high as
160 MB per second if technology breakthroughs, which the
LTO partners say are probable, can be realized.
These far-future Ultriums, as well as the ones that will be
available next year, will compare rather nicely to IBM's
3590 Magstar tape drives. The 3590 B models using an
extended length tape that, IBM announced a few months ago,
can cram 20 GB of capacity on a single Magstar cartridge
and up to 60 GB with the 3:1 LZ1 data compression algorithm
implemented. These B models record data using special
magneto-resistive tape heads that paint 128 tracks across
the tape. In theory, the 3590 B models have a data transfer
rate that ranges from 9 to 40 MB per second. IBM's initial
tests on AS/400s showed it could move data at about 17 MB per second
when moving large files. The E models in the
3590 line record data in 256 tracks, rather than 128 tracks,
and can therefore pack up to 40 GB of data in native mode
and up to 120 GB of data with compression by using the new
extended format. The E models have a data transfer rate
that ranges from 14 to 40 MB per second. For planning
purposes, IBM tells customers to count only on the lower
transfer rates of 9 MB per second for the Bs and 14 MB per
second for the Es. With 3:1 data compression, that gives
the Bs a 27 MB per second data transfer rate and the
Es a 42 MB per second data transfer rate. So the 3590s will still
be able to best the Ultriums on intensive read-write
workloads and on raw speed, since the Ultriums will have
only 2:1 data compression and will only be able to move
compressed data at 30 MB per second. The Accelis LTO units,
which presumably are not far behind the Ultriums in coming
to market, will offer native capacities of 25 GB, 50 GB,
100 GB, and 200 GB as the generations progress. Data
transfer rates will be the same as the Ultrium units. Aside
from capacity differences, the Accelis units will be
optimized for more rapid access of information stored on
the tape. To accomplish this task, the initial Accelis tape
units support only 256 data tracks spread across two 128-
track bands. Having fewer bands doesn't make data transfers
any faster, but it does make it quicker to find a random
file stored on the tape unit. To make the math work out,
the Ultrium unit has to have 2.67 times as much tape in the
cartridge as the Accelis unit. Presumably, on average, the
seek time will go down by that proportion when comparing
the Accelis and Ultrium units. Both the Ultrium and Accelis
LTO tape drives borrow heavily from IBM's 3590 technologies.
The Anaconda tape library, which IBM is just starting to
show customers, has a 280-cartridge capacity and supports
multiple Ultrium LTO tape decks. That's about 28 TB of
uncompressed archive capacity and double that with
compression on. My sources at IBM indicate that this
Anaconda configuration will be neither the largest nor the
smallest configuration. Odds are, IBM will have libraries
that support hundreds of terabytes of archiving capacity
and dozens of Ultrium decks. Big Blue will probably also
support a mix of Ultrium and Accelis decks down the road.
My sources also say that Paramount Picture's Entertainment
Tonight television show will buy one of the first Anaconda
libraries so that it can archive 20 years of broadcasts,
comprising over 100,000 hours of shows. Anaconda is
expected to be available in late summer.
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