The DDS-4 (3MB/sec/6MB/sec, 20GB/40GB) is a fairly good low-cost backup
format.  It is speedy compared to DDS-2 and DDS-3 but still a far cry, from
DLT8000 (6/12, 40/80) and LTO drives (15/30, 100/200).  It compares with
DLT1 drives (3/6, 40/80).  In the past, the roadmap on DDS included DDS-5,
which was slated to come out this year.  I cannot find anything on the HP
web site about DDS-5, it's as if the site had been cleansed of any reference
to it.  I remember reading a white paper at the HP website about 2 years ago
on this technology.

The future right now is being divided into 2 main camps:  LTO Ultrium and
Accelis and DLT & SDLT.  There are other formats such as AIT, 9940, etc, but
LTO and DLT are the two main ones.

DLT currently has the lion's share of the market with a million drives and
tens of millions of tapes sold.  The latest iteration of the DLT is called
SDLT320 (16/32. 160/320), using a Super DLT 1 tape.  This ups it from the
SDLT220 (11/22, 110/220), also using a Super DLT 1 tape.  The advantage of
the SDLT (either one) is they can read from (but not write to) DLT IV tapes.
For DLT shops with large investments in DLT tapes, this may be the natural
progression.  However, HP doesn't want to support SDLT on the 3000 and
whilst I can understand the reticence since HP makes the LTO, I think it is
somewhat shortsighted to force the current DLT users to invest in yet
another non-compatible format.

LTO (Linear Tape Open) is from a consortium made up of HP, Seagate and IBM.
The LTO comes in two flavors, Ultrium, which is very much like a DLT in
terms of performance and capacity and Accelis, which is closer to a MagStar
in performance and capacity.  I have no experience with Accelis.  The LTO
format is new.  It really started last year and after a period of growing
pains and debugging, is finally living up to its billing.  All three major
players make their own drives, so you can buy a library with HP LTO Ultrium
drives, IBM LTO Ultrium drives or Seagate LTO Ultrium drives.  Currently the
top end performance is 30 MB/second compressed with 200GB (compressed)
capacity per cartridge.  We have several customers in the large Unix world
who definitely experience this throughput and somewhat more besides.  After
18 months of fighting with this format, I have grown very fond of it.  So
much so that I now hold DLT7000/8000 if not in contempt, at least in less
favor than before.  On Windows 2000 systems with a good RAID array
controller, you can make these devices scream.  The major issue with these
fast drives is how fact can you get data off the disk drives so as to feed
the tapes continually.

For the 3000, I believe at the Solutions Symposium, CSY said they were
looking at supporting LTO Ultrium drives in the near future.  That would be
a good thing.  I do not think that booting or updates via Ultrium would be
supported, but backup and restore with these devices would be great.

I would also urge HP to reconsider supporting SDLT, simply because of its
backward compatibility with DLT-IV tapes.  I would also urge HP to have
support for the DLT1 drive..  It is low-cost, as fast as a DDS-3 and double
the capacity of a DDS-4.  And to my mind, more reliable than DDS.


Denys

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On Behalf Of
Duane Percox
Sent: Friday, June 21, 2002 6:59 AM
To: [log in to unmask]
Subject: Re: MPE/ix and DDS drives -future?

I bet Denys has good info on this topic, but I
can offer our personal experience of non-dds
backup devices.

* We have used DLT on our 3k systems for 2.5 years
  and wouldn't go back to dds. The performance
  and reliability is soooo much better.

* We had made the same conversion (dds to dlt) for
  our NT server farm even earlier. We recently
  upgraded this from dlt to lto (100-200gb). We
  have been very pleased with lto.

* We sure wish hp would support the lto drives THEY
  make (ultrium) on the hp e3000.

duane percox


Bill Brandt wrote:

>I just bought some new tapes for our backup and the salesman
>said that DDS is being phased out.
>
>If so anyone care to opine the options down the road?

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