Parking disk drive heads

[Eric Anderson]

M. Warner Losh wrote:
> In message: <200508201230.37976.hselasky at c2i.net>
>             Hans Petter Selasky <hselasky at c2i.net> writes:
> : On Saturday 20 August 2005 10:18, Mike Silbersack wrote:
> : > On Fri, 19 Aug 2005, Doug Ambrisko wrote:
> : > > Flash is nice but it has some issues.  Atleast dropping it isn't one!
> : > >
> : > > Doug A.
> : >
> : > I'd be really happy if I could get a USB flash drive to last more than 8
> : > months.  Luckily, I started weekly backups after the first failure.  That
> : > helped a lot when the second failure happened.
> : >
> : 
> : Flash drives does usually not last more than 10000 writes, per bit, from what 
> : I know. Probably you need some kind of special file-system that moves the 
> : files around as the write quoute gets used up! Eventually the size of the 
> : disk will reach zero, and you have to move the files elsewhere :-) But this 
> : is probably off topic.
> 
> Actually, 10,000 writes per bit is one or two orders of magnitude too
> low these days.  It was more typical for the Linear Flash PCMCIA cards
> from 10 years ago.  Today, typically flash devices are good for more
> like 100,000 or 500,000 writes per cell, and all the fobs you'd buy
> these days have built-in wear averaging.  I've tried three times now
> to wear out a flash by writing an incrementing counter to a single
> location only to give up after weeks of hammering due to external
> factors (power failure, network failure, etc).

As a data point, I've been using 64mb compact flash cards (rated at 100k 
writes) in about 100 Soekris boxes (running FreeBSD) for about 4 years, 
and they are all still working, except for one.  Now, most compact flash 
cards are rated at 1 million writes.

And yes, I'm logging to the card and everything..

Eric



-- 
------------------------------------------------------------------------
Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------------------