Hello all,
The saga continues! Recently I posted to see if anyone could uncover
the mystery of the latest technology high speed tape drives (original
post added later). There still are no answers.
I had mentioned in my original post that i need an UNCOMPRESSED spec
since part of this is "home made" and hardware compression is already
being done. As for the spec that Exabyte gave on the Mammoth drive of
3Mb/sec UNCOMPRESSED, there was no need to look at the DLT drives which
had an UNCOMPRESSED transfer rate of only 1.5Mb/sec. The group here
wanted the 3Mb/sec.
As for the 2 vendors that told me that they could get no where near the
3Mb/sec mark, they stand by their numbers BUT there are now 2 other
vendors that will gaurantee me the 3Mb/sec UNCOMPRESSED WRITE rate so I
guess the other 2 vendors either need to get their act together or will
have a good laugh. I also called Exabyte directly and they stood by
their original Spec of 3Mb/sec write rate.
Since this drive still hasn't shipped yet...who knows! I believe that
at some point everyone will make good on the 3Mb/sec. I know that the
DLT 7000 is spec'd at 5Mb/sec but that is even further off than the
Mammoth. We have a JUNE deadline on the project so we can't wait that
long.
The way I see it, if it's gauranteed I can always return it and tell you
guys to be careful doing business with that specific company. The
answer is yet to come.
BTW--I know there are other options such as multiple drives using
striping and such, however, it's one of those situations where you want
the best but you don't want to pay that price.
------------------------------------------------------------------------
My original post:
I am quite confused about the latest in high speed removable media
specifically regarding 8mm technology.
Supposedly Exabyte had announced the Mamoth drive a few years ago and
still has not delivered! It was supposed to be an 8mm Metal evaporated
tape media unit that would store up to 20 gigs of data UNCOMPRESSED at a
transfer rate of 3mb/sec sustained.
Well, I spoke with a vendor who has helped in testing the drive for
exabyte and who also writes their own drivers for the units (supposedly
10% faster drivers than sun had written). They tell me that the best
response they can get out of the unit is 700k/sec sustained and that
this is a compression ONLY(?!@#?) drive. Their info is that the drive
will be released by Exabyte by the end of the month.
Yet another vendor who is a VAR for Exabyte didn't even know that the
drive was to be released soon.
Now, There is a vendor called Cybernetics that basically repackages
hardware and writes software for them. They have an 8mm high speed tape
system that is advertised to run at 3MB/sec UNCOMPRESSED with a capicity
of 20 megs. Their ship time is 14 days and they have already shipped
other orders. When they were asked if this was their own drive they
responded by telling us that it was an Exabyte Mamoth drive repackaged!
Is this possible? Is it true? I have not been able to speak with
anyone directly and the only one here htat has spoke to a sales person
not a tech.
Even the DLT drives only write at 1.5mb/sec uncompressed. How can a
helical scan 8mm tape works so fast. Could this be a marketing trick
with smoke and mirrors? Could the transfer rate be different from the
write speed?
We ultimately would like to store at 3mb/sec on hopefully a 20meg tape
with NO compression (it's already being crunched as much as it can be
before it gets to the drive). In some cases we are writing 8gigs per
hour already so we need fast high capicity storage.
------------------------------------------------------------------------
Thanks to:
------------------------------------------------------------------------
From:
Brad Young <bbyoung@amoco.com>
To:
Systems Administrator <sysadmin@astrosun.tn.cornell.edu>
We've found DLTs to be superior to Exabytes. DLTs are not without
problems, but later models behave better... DLT7000 promises to deliver
5mb/sec writes. I'm not certain of the amount of data that can be
written. DLT7000 will be f/w/differential SCSI only.. Delivery date...
supposedly summer..
-----------------------------------------------------------------------
From:
jeffw@triple-i.com (Jeff Wasilko)
To:
sysadmin@astrosun.tn.cornell.edu
The new DLT 7000 stores 35/70 gigs and I think writes up to
5mb/sec using compression (I would assume it writes 2.5mb/sec
uncompressed). Check www.quantum.com for details.
------------------------------------------------------------------------
From:
rtrzaska@uk.mdis.com (ray)
To:
sysadmin@astrosun.tn.cornell.edu
according to exabytes product information at
http://www.Exabyte.COM:80/Products/8mm/Mammoth/Ifeatures.html
the device is called Mammoth ( not mamoth ) and
it is 40GB capacity compressed ( assuming 2:1 compression so 20GB
uncompressed ) and
tape speed is 6MB/sec ( also at the 2:1 compressed rate )
it uses AME data-grade EXATAPE 170m 8mm media
MTBF 200,000 hours
this is available only as an OEM/system integrator product, and
is not available on the ready to install products.
------------------------------------------------------------------------
From:
Robert.Gillespie@waii.com (Robert.Gillespie@waii.com)
To:
sysadmin@astrosun.tn.cornell.edu
CC:
rob@oak.london.waii.com
Hi Vic
DLT is the answer
I have been using DLT2000 (2.6, 6, 10 & 20 Gb) for nearly THREE years
Every night I do incremental backups (level7's only) from a mixture of
22 x Sparc 2 10 20, to a 630MP running 4.1.2 with the DLT device on a
SCSI-2
Board (PTSCII).
The overnighter is about 50 filesystems of Seismic Data (mostly bigger
than 1 Mb),
including home dirs, mail spools etc
I expect to get very near to capacity of 20Gb compressed in a time
of about 7 - 8 hours (depending on source machine's ie 2 or 20)
Last week I looked at timings from a sparc20 to DLT
DEC 3210 2.1 Gb disk
SPARC-20/61 64Mb 10 M/sec UTP ethernet
This gave a throughput of 1.433 Mbytes/sec
(1,652,413 Kbytes in 18 mins 46 secs)
I Have been buying my disk drives and DLT from RARE systems in Houston
TX
for last 7 years (since 3/260 days!!)
They are great !!!
They will be able to help/advise/sell on these matters.
R.A.R.E Systems 713 467 7273 (salesman Britton Dick)
Maybe a raided DLT system would be the answer ???
------------------------------------------------------------------------
From:
misawa@physics.Berkeley.EDU (Shigeki Misawa)
Reply-To:
misawa@physics.Berkeley.EDU
To:
Systems Administrator <sysadmin@astrosun.tn.cornell.edu>
Why not go to the exabyte WWW page and get the info from the horses
mouth ?
Note also, that if write speed is what your looking for, I have seen
vendors that provide "RAIT"ed tape systems, akin to RAID's
(Redundant Array of Inexpensive Disks).
Given that the product (the mammoth) is so late to market, do you
really want to trust your data on it ?
If I were you I would go with DLT's
Shigeki Misawa
Graduate Student
Solaris SysAdmin
UCB Physics Department
URL: http://dogbert.lbl.gov/~misawa
------------------------------------------------------------------------
--
***************************************************************
Systems Administrator
---------------------
Space Sciences Building CRSR
Mail all system related problems to one of the following:
sysadmin@astrosun.tn.cornell.edu root@astrosun.tn.cornell.edu
sysadmin@spacenet.tn.cornell.edu root@spacenet.tn.cornell.edu
or see
Vic Germani in room 402 germani@astrosun.tn.cornell.edu
***************************************************************
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