[GLLUG] USB Backup Media
Marr
marr at copper.net
Thu Feb 18 22:07:00 EST 2010
On Wednesday 17 February 2010 10:31:08pm Chick Tower wrote:
> I had considered buying an external hard drive that attaches via a USB
> port for backing up my PCs. Then it occurred to me that I could do the
> same thing with flash drives, and they would be even more portable and
> would save me money. I could probably get by with 4GB drives, but 8GB
> ones aren't much more expensive. I know that the flash drives have a
> limited number of write operations before they fail. Does anyone know
> if they fail completely, or if there are any warning signs before they
> fail?
>
> I figure, to minimize writes, I would tar the files to be backed up on
> some extra space, or another partition, on the PC's hard drive and then
> copy that file to the flash drive. If a flash drive fails, I can just
> pop in another one in its place. Does anyone see any drawbacks to using
> flash drives as backup media?
I've been using USB flash RAM drives for backups for almost 7 years now and
have had no problems. But I use them for _incremental_ (hourly, in my case,
started by a 'cron' job) backups, not full system backups. This way, I can
never (in theory) lose more than 1 hour's worth of effort. A 256 MB USB flash
RAM drive (formatted with an 'ext2' filesystem) for just this purpose is
always connected to my primary PC.
I basically do what you've suggested -- make a tarball on the HDD and then
copy it to the USB flash RAM drive. As Charles wisely suggests, you should
checksum the 2 tarballs to help assure data integrity. A couple of
simple 'md5sum' commands is all I use.
The first USB stick (Apacer 128 MB) worked fine for almost 5 years. I replaced
it for a larger USB stick (Apacer 256 MB), not because of any failures or
problems but because I was occasionally overflowing it (because I keep 12
days of hourly incremental backups on the same USB stick -- older tarballs
are automatically deleted by the full-system backup job).
As for failures in general, I can't offer much. The only USB stick I've had
fail was an old SanDisk 'Cruzer Mini', way back in 2004. I never used it as a
backup device, so it hadn't seen much use. It had been acting weird for a
long time though, often not being consistently recognized when plugged in or
not showing partitions properly/consistently. The final straw was when it
failed a 'mke2fs' command to re-format it. The message was:
Writing inode tables: 0/26
Could not write 8 blocks in inode table starting at 5: Attempt
to write block from filesystem resulted in short write
I sent it in under the 2-year warranty and got a free replacement from
SanDisk. The replacement has seen little use since then but, as far as I
know, still works.
HTH....
Regards,
Bill Marr
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