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Re: run debian off usb flash drive

Marc Singer <elf@buici.com> writes:

> On Sun, Mar 07, 2004 at 03:06:37AM +0100, Steinar H. Gunderson wrote:
> > On Sat, Mar 06, 2004 at 08:25:50PM -0500, Jeff Johnston wrote:
> > > With 512 MB and 1 GB USB flash drives becoming cheaper and cheaper I'm
> > > thinking that it would be a fantastic way to have a boot drive with no
> > > moving parts that could (almost) never die of old age.
> > 
> > Just a side note: They'll probably die a lot quicker than your hard drive,
> > given that you're not mounting them read-only. Those things have a more or
> > less fixed number of writes before they start to break.
> Doesn't it matter how the system is used?  
> Most of the flash parts are rated for 100K erase cycles per 128KiB
> block (StrataFlash).  Cheap hard drives are usualy waranteed for only
> one year.  Assuming the best case for flash, and worst case for a hard

2 years from the seller required by law in germany, usually 3 to 5
years manufacturer warantee on disks. 5 year warantee on sticks/flash
cards too (which doesn't mean they won't fail a lot sooner).

> drive, the flash device can take about 250 block erase cycles/day in a

And you get one every 3 seconds on some blocks. Thats 28800 a day.
Thats atime updates for you. One should be carefull setting that up.

> year of continuous use.  The wear-leveling flash filesystems will
> substantially extend the lifespan of the flash device.  If the system
> is setup to reduce unnecessary writes to the flash device, it seems
> possible to get many years of use before the flash device fails.
> In other words, it seems reasonable to use flash as a hard-drive
> replacement as long as one is clever.

I would setup a ramdisk system or a lvm snapshot (flash stick R/O +
ramdisk as copy-on-write storgae). Better not write to the stick if
not neccessary.

With lvm you can just hit reboot to get the original setup or move the
changed blocks onto the stick to change the stick itself. Having the
stick R/O also means no fsck or journal (oh yeah, journaling on
sticks, instant death :) commits and no filesystem corruption

Instead of a stick you could also use a CDr(w) or DVDr(w). Nice for a
router. If you think it got compromised, hit reboot.


PS: D-I supports being put on an usb stick, boot that and install
debian from it. Installing too it should be easy to add too.

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