This issue was addressed a number of times in the past, but seems to get
forgotten and so it appears again every now and then.
This issue has only become apparent in the last few years, when high speed tape
drives became available. The DLT7000 was the first drive that showed it could
not be driven to its full potential on the HP 3000. Up to that point, people
had been using DLT-4000, various DDS, 9 track tapes and QIC. These
technologies were very slow, compared to the disk speeds. The DLT4000 was more
balanced, but could still be driven at its top speed on the HP 3000. From the
DLT7000 on, this is no longer true. Several years ago, we (Hicomp) encountered
the problem on other platforms and dealt with it.
The basis of the performance problem is not with how fast the HP 3000 can drive
a DLT 7000 or 8000 or S-DLT or an LTO (which is not presently supported,) but
rather, how fast (or slow) the data can be stripped off the disk drives.
Several months ago, I posted that if people wanted to see the ultimate speed
of the backup product they were running, they should simply backup to $null.
In other words, take the drive and its connection out of the equation. Just
see how fast you can get data off the disk drives. That is the limiting factor
in the backup equation, provided you do backups to a locally-attached tape
device. If you do backup over the network to a remote tape drive, the network
will probably become your limiting factor. The various responses that came
back, showed a speed of about 3.5 MB/second. This had been our experience as
well. This is a far cry from the 10 and 12 MB/second touted for the DLT7000
and DLT8000.
When the tape drives were slower than the disk drives, people used multiple
tape drives to get the backup done quicker. Conversely, when the tape drives
are faster than the disk drives, one should use multiple disks to backup to a
single tape drive. For Hiback, this concept is called multiplexing. This is
where Hiback takes multiple streams of backup data and joins them together on
the same tape drive, thus presenting the tape drive with a sufficient aggregate
data stream to keep the tape streaming at its top speed. Whilst we have had
this technology for years on HP-UX and other UNIX platforms, we have introduced
it to MPE only this year. So, whilst I do not remember for sure Carl testing
our software, I am positive he did not test the multiplexing capability.
In the past, on a large SUN machine (E10000), with multiplexing a good number
of disc drives to 3 IBM MagStar tape drives (these make the DLT7000 look like a
DDS-1), we have experienced aggregate backups speeds exceeding 1 terabyte per
hour.
So, in our experience, in a file system backup, the only way to stream a tape
device which is rated faster than about 3-4 MB/second, you must have multiple
streams feeding that tape device. The difference will be in the
implementation. With Hiback on the HP 3000, we have the capability to
multiplex multiple streams coming from the same machine or different machines
(over the network.) Single processor machines need not apply.
Kind regards,
Denys. . .
Denys Beauchemin
HICOMP
(800) 323-8863 (281) 288-7438 Fax: (281) 355-6879
denys at hicomp.com www.hicomp.com
-----Original Message-----
From: Carl McNamee [SMTP:[log in to unmask]]
Sent: Monday, December 04, 2000 8:57 AM
To: [log in to unmask]
Subject: Re: Disk capacity on an 979KS
A year ago I found the same problem as Chris and reported it to HP. They
promised that Store's performance would be addressed up but so far nothing.
:(
If you want to drive the DLT7000 at its rated capacity the only product I've
found is Orbit. We choose not to implement Orbit for various reasons, but
it will do the trick. At the time I also tested Roadrunner (now BackPack),
Legato, HighBack, and Veritas and they all had performance similar to
Store's.
Currently, we run our DLT4000's on a dedicated S/E scsi channel and seem to
be able to keep them streaming without much trouble, now. I must admit that
I went through a lot of work to load balance all the i/o and disk on our
systems to make it happen. There is not any way to keep a DLT7000, and by
definition any faster devices, streaming with the current versions on Store.
Let's get some phone calls into the RC and let HP know that this issue needs
to be fixed! And fixed quickly!
Carl McNamee
Systems Administrator
Billing Concepts
(210) 949-7282
-----Original Message-----
From: Chris Goodey [mailto:[log in to unmask]]
Sent: Saturday, December 02, 2000 6:50 PM
To: [log in to unmask]
Subject: Re: [HP3000-L] Disk capacity on an 979KS
I believe you will have trouble getting
more than 5-6 megabytes a second out of Hp's store.
We recently switched to DLT-7000s, with a native speed
of 5mb a second, so should get maybe 10-15 mb a second
with the easily compressible data.
However, the HP staff admits that Store (and Turbo store)
has a bottle neck making it impossible to achieve speeds much
more than 5-6mb/sec.
<big snip>
Do DLT-4000s work well on the 8 bit interfaces, or do
they really need their own dedicated 16bit channel?
Anyone getting much more then 6mb/second on a DLT7000-8000?
If so, how? and what did it cost?
-----Original Message-----
From: Neil Harvey [mailto:[log in to unmask]]
Sent: Friday, December 01, 2000 8:59 PM
To: [log in to unmask]
Subject: Re: [HP3000-L] Disk capacity on an 979KS
>From the PDF file (which took a while for me to download) :-
http://www.hp.com/storage/pdf/NETDESK_ULT230.pdf
tape speed 4.1 minutes per second
Yes folks, promising technology indeed!
Neil
-----Original Message-----
From: Neil Harvey [mailto:[log in to unmask]]
Sent: Saturday, December 02, 2000 6:54 AM
To: [log in to unmask]
Subject: Re: Disk capacity on an 979KS
Greetings
Backup is becoming a real issue on our Health Care sites - even on a small
site, capacities run into 80 - 90 GB.
We use DDS3 now, sometimes in parallel, and try to keep backup times down
below 2 - 3 hours, but this becoming unworkable.
With Hardware Compression, we generally get a 3 -1 ratio, so we can fit up
to 36GB on a single media.
I don't think DDS4 is supported on K series boxes (our favourites).
I'm looking for a quantum leap in backup speed.
At HPWorld I saw LTO (Linear Tape Open) drives and media.
>From HP's website at http://www.hp.com/tape/ultrium/index.html :-
"The ultra-fast HP SureStore Ultrium 230 stores up to 200 GB* of data on a
single tape at a sustained transfer rate of 30MB/s*. With ultimate
reliability and ease of use in mind, the rugged design builds on the best
existing technologies to create a new level of data protection."
Now, this sounds better - If I can get 3-1 on these babies, I'll have 300 GB
per stick, all within 2 hours. And the technology is at it's very beginning
- so we should expect the same exponential advances as we saw with DDS - 1
through 4.
Question is, are they real, and do they work on K series HP3000's?
Of course, I won't retire until there is Liquid Memory Technology (LMT)
available on tap, and we can just pour data into LMT Vessels :)
Regards
Neil
-----Original Message-----
From: Stan Sieler [mailto:[log in to unmask]]
Sent: Saturday, December 02, 2000 2:03 AM
To: [log in to unmask]
Subject: Re: Disk capacity on an 979KS
Re:
> The Fast Wide SCSI limit is 15 devices per channel,
> although this is not recommended for performance reasons.
> I don't think HP currently supports drives larger than
> the 36GB ones, which would limit you to 540GB per controller.
MPE/iX 6.5 supports 72 GB drives, which (at 15 per channel) would
be 1 TB per controller!
That question about backing it up just got harder :)
> You can add several I/O expanders, with their own card cage,
> and an additional HP-PB expansion, etc. (The HP-PB only goes
> to 32mb a second, so several SCSI channels per PB can keep
> it mighty busy.)
<plug> DiskPerf, from Allegro, could be used to test the
I/O capacity of a system.
</plug>
Stan Sieler [log in to unmask]
www.allegro.com/sieler/wanted/index.html www.allegro.com/sieler
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