Date: Sat, 20 Aug 2005 21:44:18 -0500 From: Eric Anderson <anderson@centtech.com> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-hackers@freebsd.org, hselasky@c2i.net Subject: Re: Parking disk drive heads Message-ID: <4307EA82.7040108@centtech.com> In-Reply-To: <20050820.171238.122195775.imp@bsdimp.com> References: <200508200359.j7K3xoHF015718@ambrisko.com> <20050820031508.A73274@odysseus.silby.com> <200508201230.37976.hselasky@c2i.net> <20050820.171238.122195775.imp@bsdimp.com>
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M. Warner Losh wrote: > In message: <200508201230.37976.hselasky@c2i.net> > Hans Petter Selasky <hselasky@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. ------------------------------------------------------------------------
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