[SAGE-AU] Re: [Talk] Reality check...

Peter Jeremy peter.jeremy at alcatel.com.au
Fri Sep 13 13:51:26 EST 2002

On 2002-Sep-13 13:21:31 +1000, David McDonald <david.mcdonald at securitymail.com.au> wrote:
>I'll second that. The fastest tape drives in general circulation that I am
>familiar with operate at around 6 Mbytes/s (maximum).

DLT7000 is ~5MB/sec native.  DLT8000 is ~6MB/sec.  Super-DLT is
10-12MB/sec native and LTO is up around 15MB/sec.  I agree that this
is slower than sequential disk access for any respectable disk.

In my experience, the limiting factor is either trying to get the
data out of the filesystem (UFS+dump can be quite slow due to the
level of seeking and small read size) or trying to compress it in
the host (tape compression mightn't be as good as gzip, but you
need a very grunty CPU to get 5MB/sec into gzip, let alone managing
to saturate a tape drive).  [This brings up another advantage of
disks - sequentially writing 2MB/sec to a disk causes lots less wear
and tear than writing the same rate to a faster tape drive.]

> 2.5" drives (designed for laptops) are typically quite robust
>(in disk drive terms) and if they are suitably padded in a case
>should be extremely robust - quite likely better than many tapes

The downside is that 2.5" drives are substantially more expensive,
slower and smaller (capacity) than 3.5" disks.  You lose most of
the advantages of moving to IDE disks.

>My suggestion is if you want to transport disk drives regularly, drop in at
>one of the many electronic hobbyist stores and get yourself a strong case
>with foam rubber padding.

If you've got lots of disks to carry, these would be ideal.  They are
overkill for one or two disks.  Maybe a heavy-duty lunchbox packed
with high-density foam would be a good solution there.


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