[Soekris] Solid state filesystem lifetime

M. Warner Losh imp at bsdimp.com
Wed Feb 5 05:34:01 UTC 2003


In message: <4046749.1044422560700.JavaMail.js114732 at texsun.Central.Sun.COM>
            John.Simon at sun.com writes:
: I guess the question that begs to be asked is does CF have wear
: leveling built in? If not is it built into your OS?

Usually the wear-averaging is built into the CF part.  I've heard
claims that you get closer to 1M writes per cell than 100k that is
quoted in earlier reference material.  I've destructively tested two
flashes.  It took me about two months of hitting one CF as hard/fast
as I could (through the FS, with sync writes) to wear it out.  The
second don't wear out in three months of up time that the machine
doing the test had.  Same test both times, different brands.  These
were 64M parts back when they cost $125 each.  This was under freebsd
and the test was something like:

    while true; do
	  dd if=/dev/random of=/mnt/file bs=512 count=1
	  dd if=/mnt/file of=/dev/null bs=512 count=1
	  sync
    done

but with a little more smarts than is listed above to count
iterations, only od a fsync, etc to make sure that every write appened
(since I read it back to verify).

Warner




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