Date: Sat, 20 Aug 2005 23:30:55 -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: <4308037F.3000906@centtech.com> In-Reply-To: <20050820.214730.56826446.imp@bsdimp.com> References: <200508201230.37976.hselasky@c2i.net> <20050820.171238.122195775.imp@bsdimp.com> <4307EA82.7040108@centtech.com> <20050820.214730.56826446.imp@bsdimp.com>
next in thread | previous in thread | raw e-mail | index | archive | help
M. Warner Losh wrote: > In message: <4307EA82.7040108@centtech.com> > Eric Anderson <anderson@centtech.com> writes: > : 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.. > > The biggest failure mode of CF cards that we've seen in our boxes is > static zapage. We get more CF cards back that didn't fsck due to a > power failure, etc than we do worn out cards, or even static zapped > ones. The static zapping usually happens when we're popping the old > one out and a new one in... We think we may have seen one power surge > related failure, but we're unsure. We've fielded about 1000 CF cards > over the past 6 years... Cool, great info - thanks. If I may, what are these cards doing? (anything cool?) - or at least, what company are you working for that uses this many for some purpose? (simply curiousity) Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4308037F.3000906>