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Subject: Removable media

Removable media

From: Jonathan Farley <j.farley>
Date: Friday, August 6, 2004
Robin Siegel <rsiegel [at] ngs__org> writes

>I have started using my camera's Compact Flash cards to carry files
>from one computer to the other, and also to back up my computers in
>case of a failure. I work on our disaster preparedness committee,
>and I'd like to be able to recommend this as a good backup medium,
>but I don't know if there might be a reason not to.
>Does anyone else use these handy little cards (or the equally handy
>thumbdrives) as backup media? Any information would be appreciated.

CF Cards make an excellent temporary storage media, they appear to
be durable, I have even driven over one (by accident, not design)
and still used it.

I use a 32Mb CF card as the mirroring backup on my laptop, via a
PCMCIA converter (for any technophiles like me out there, it is part
of a Raid0 array with a matching partition on the laptop's HD:
Fedora Core Linux). This ensures that I have a continual backup of
all my documents, which happens with every disc write.

The downside is that every time you write to a CF card, or format
it, it looses a small amount of its capacity. The amount is very
small, one or two bytes each time, but the more file writes you do,
the more you will lose. This means that using it for a mirroring
backup like I do, I had to make an allowance for loss of capacity
over time as well. In the last 12 months my present CF card has
decayed to 30.2Mb, that is 0.15Mb per month. The data I store on my
laptop HD is about 25Mb, and so I will need to replace the card in
another two years or so, in actual fact, I will probably have
replaced it earlier than this.

Even so, I wouldn't rely entirely on this as my only backup. My
laptop is programmed to power on and do a full backup to my
fileserver via WAN at midnight each night, just to be sure. The
fileserver has two Raid0 HDs and backs those up to a tape on a
weekly basis, just to be extra sure.

I have an unrecoverable HD hanging on my wall with a lost 70,000
words of the first book I wrote (1989), reminding me never to take
chances and use every method available to me to backups my files.

Jonathan S Farley MA ACR MIPC
Senior Conservator
Royal Botanic Gardens
+44 208 332 5419
Fax: +44 208 332 5430

                  Conservation DistList Instance 18:11
                 Distributed: Thursday, August 12, 2004
                       Message Id: cdl-18-11-004
Received on Friday, 6 August, 2004

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