Messages in this thread | | | From | Joshua Kugler <> | Subject | Re: Lifetime of flash memory | Date | Tue, 21 Mar 2006 09:20:53 -0900 |
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On Tuesday 21 March 2006 08:01, John Richard Moser wrote: > I have a kind of dumb question. I keep hearing that "USB Flash Memory" > or "Compact Flash Cards" and family have "a limited number of writes" > and will eventually wear out. Recommendations like "DO NOT PUT A SWAP > FILE ON USB MEMORY" have come out of this. In fact, quoting > Documentation/laptop-mode.txt: > > * If you're worried about your data, you might want to consider using > a USB memory stick or something like that as a "working area". (Be > aware though that flash memory can only handle a limited number of > writes, and overuse may wear out your memory stick pretty quickly. > Do _not_ use journalling filesystems on flash memory sticks.) > > The question I have is, is this really significant? I have heard quoted > that flash memory typically handles something like 3x10^18 writes; and > that compact flash cards, USB drives, SD cards, and family typically > have integrated control chipsets that include wear-leveling algorithms > (built-in flash like in an iPaq does not; hence jffs2). Should we > really care that in about 95 billion years the thing will wear out > (assuming we write its entire capacity once a second)? > > I call FUD.
Search for a thread on LKML having to do with enabling "sync" on removable media, especially VFAT media. If you are copying a large file, and the FAT on the device is being updated with every block, you can literally fry your device in a matter of minutes, because the FAT is always in the same spot, thus it is always overwriting the same spot.
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-- Joshua Kugler PGP Key: http://pgp.mit.edu/ CDE System Administrator ID 0xDB26D7CE http://distance.uaf.edu/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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