Re: Data Archive Methodology

Ray Hicks (rh208@cus.cam.ac.uk)
Wed, 28 May 1997 18:20:36 +0100

Hi Robert,

If you want an offline archive, you should look into retrospect remote. It
will do incremental network backups on several machines (including pc's I
think), and allows you to use most media. I had a (DAT) tape streamer in
my last lab, and scheduled backups weekly for most mac's and daily for our
imaging mac using retrospect. The first backup is quite protracted, but
the incremental ones depend on how much data has been added since the last
archive. Retrospect allows you to manage duplicate (or higher replicate)
archives so you can rotate your medium in case one tape or disc goes bad.
When backups are completed retrospect will shut down your macs (other than
LC and SE/Plus).

You can extract individual files or groups of files, or even reconstitute a
crashed disc from the archive, but it is a more complex operation than
dragging an icon. The big advantage of this type of software is that it
will optimise medium usage by checking to see that files are altered or new
before adding them to the archive, and they work automatically and keep
track of which file is on which tape/disc, so you can't be blamed for
forgetting that essential file that someone saved two years ago and have a
sudden need for.

It is possible to get non-archival drivers for tape streamers that make
them behave more like a disc (ie you can mount them on the desktop and
copy/trash files in the normal way), we had retrospect and a mounting
driver bundled with our streamer, so people could, if they wanted to, have
their own removable collection of files on a 4 gigabyte tape.

DAT is very cheap per megabyte, and the streamers are too, however access
times for individual files can be slow (unless the files you want are
adjacent on the tape), Optical drives are pretty slow, and the medium is
expensive, rewritable CD's are great for making bootleg audio CD's, but the
only one I've played with had dreadful software and documentation (the
reason I played with it was that the people who'd bought it, thought it
didn't work, because they couldn't access any of the files on it until they
"burned" it, which they didn't want to do until it was full).

No matter what medium you settle on I'd recommend Retrospect as archival
software, and it would be worth looking for a driver that has it bundled.

Ray

At 11:03 am +0000 27/5/97, Robert Pyle wrote:
>I know this subject was discussed some time ago but I need to know some more
>information. We are interested in purchasing a data archive system that will
>serve our entire lab. In the lab we have a FACS Vantage, FACScan, FACS
>Caliber,
>FACS Trak and a Discovery Image analyzer. We want a single archive system
>that
>will be compatible with both the Macintosh platforms attached to the flow
>cytometers as well as the IBM Dos system attached to the Image analyzer.
>Considering the size of the files to be saved we are currently leaning toward
>either a writable CD or an Optical drive. Price is a consideration but we
>want
>something flexible and useful for all the systems.
>
>Has anyone tried to do such a thing in their lab? What is the available
>advice
>based on personal experience?
>
>Your patience and consideration of my question is much appreciated.
>
>Haywood Pyle
>King Faisal Specialist Hospital and Research Center
>Flow Cytometry Core Facility
>pyle@kfshrc.edu.sa

Ray Hicks
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