Re: off-site backup
dtutty@porchlight.ca writes:
> On Mon, Oct 16, 2006 at 11:06:22AM -0600, Cedar Cox wrote:
>> >It seems that USB sticks/flash-drives are far more rugged than anything
>> >other than paper. What have you found?
>>
>> Flash memory does have limited write cycles. This is probably more an
>> issue for people who carry a Linux distro on their stick than you for
>> backup, but it is an item to consider.
>
> Does anyone know what the limit is? 10 years at monthy is 120 cycles;
> 10 years at weekly is 520 cycles, 10 years at daily is 3,650.
>
> Does the cycle limit apply to the whole device or does a section get
> worn out and the capacity just shrink? E.g. if I have my /etc/
> directory copied to it and one file in /etc/ changes, does changing that
> one file reduce the lifespan of the drive as a whole?
>
> I don't know how a memory chip gets translated into a 'drive'. Is it
> like a HDD with spare sectors?
You can find the answers to your questions by searching with Google; it
should not take longer than about an hours.
Flash memory is good for on the order of ten thousand (10,000) write
cycles. I think that 100,000 write cycles would be expecting too much.
How the "wear" is distributed within the device can vary from one
manufacturer to the next. In the worst case, every memory cell in the
device is written every time there is a write to the device.
Likewise, how a device handles "bad sectors" can vary from manufacturer
to manufacturer. If "fsck" finds a problem, reformat the device. In my
own use of flash devices, I have found that on some devices I need to
use "fdisk" and on others, "cfdisk".
Most flash devices come from the factory with the VFAT file system. I
have been reformatting them, then making an "ext2" file system. This
scheme has been working for me, but I would like to receive comments and
recommendations.
RLH
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