Re: Need backup hardware suggestions
From: Jean-David Beyer (jdbeyer_at_exit109.com)
Date: 09/11/04
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Date: Fri, 10 Sep 2004 23:34:20 -0400
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Madhusudan Singh wrote:
> Hi
>
> I am exploring various solutions for reliable backup for my exclusively
> Linux populated LAN (3 machines).
>
> What would provide me with the best value for money combination when
> the important considerations for me (barring cost) are :
>
> 1. Speed of backup. (I do not want to spend hours backing up a few ten
> GB's). 2. Number of cycles of backup (durability). 3. Total volume that
> can be backed up. 4. Portability.
>
> ? I need a solution that can backup upto 30 GB or so. What is better ?
> Tapes or external USB harddisks ?
>
I happen to prefer Exabyte VXA-2 tape drives, having used floppy tape
(Travan type) and DDS-2 drives and finding them unacceptable.
1.) Data transfer rate is up to 12 MBytes/sec. Ultra2 LVD/SE SCSI
interface; FireWire interface is also available for external models. The
way I do backups, speed is not all that important as I have _cron_ do the
backups at a little after 1AM weekdays and a little after 5AM on Sundays
when I can be assumed to be asleep. I just want them done before I am
using the machine.
2.) I have some tapes I have used once a week (my backup software wites a
tape, rewinds it, plays it back to be really sure it was correctly
written, rewinds it, and ejects it) in the VXA-1 drive since mid April
2001, and they are starting to produce failures immediately detected by
the software during writing (these drives are helical scan with four
heads, and in write-mode, every other head reads back what is being
written by the other two heads, so write failures are detected
immediately). Since my initial installation of the VXA-1 drive, Exabyte
has supplied a firmware upgrade said to handle the tapes more gently and
thus prolong their life. So I do not know if those tapes would have lasted
5 years instead of a little over 3 years had that firmware upgrade been in
place since the beginning.
I have never successfully written a tape and been unable to read it later.
Exabyte claim "VXAtape uses Advance Metal Evaporated (AME) technology
developed specifically to deliver the durability and capacity required for
high-performance tape drives. With a shelf life of 30 years and a usage
life of up to 500 uses, VXAtape AME has significant advantages over
conventional Metal Particle (MP) media with a specified life of 100 uses."
The VXA-2 drive has been in service only since about March 2004, so while
I have had no errors or failures, it is too soon to come to any
conclusions about reliability based on direct observation by me.
3.) These will take various different tape sizes of 40 GByte, 80 GBytes,
118 GBytes, and 160 GBytes (compressed: assumes 2:1 compreession) or 80
GBytes uncompressed. Compression is done in the hardware. A slower, lower
capacity model (VXA-1) is still available for somewhat less money.
The VXA-3 drive, not yet available, will write twice as much as this on
the same tapes.
4.) I have a VXA-1 in one of my machines and a VXA-2 in another. I can
take tapes written on the VXA-1 and read them in the VXA-2. Is that the
portability you mean? Or do you mean something like a FireWire model that
you could move from one machine to another? A third possibility is: can
you be sure VXA drives are as ubiquitous as floppy drives or CD-ROM
drives? I suppose not.
-- .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 23:00:00 up 2 days, 9:43, 3 users, load average: 4.28, 4.17, 4.13
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