Am Donnerstag, 14. März 2013 schrieb Norbert Scheibner: > Am 13.03.2013, 12:31 Uhr, schrieb Swâmi Petaramesh <sw...@petaramesh.org>: > > Le 13/03/2013 11:56, Bart Noordervliet a écrit : > >> USB flash drives are rubbish for any filesystem except FAT32 and then > >> still only gracefully accept large sequential writes. A few years ago > >> I thought it would be a good idea to put the root partition of a few > >> of my small Debian servers on USB flash, so that the harddisks could > >> spin down at night and I could easily prepare and switch a new > >> Debian-version. However, each and every USB stick got trashed within a > >> year > > > > I have an ARM box that runs a little Debian server (typically an > > advanced NAS), it uses an USB key as an ext2 root filesystem. > > Everything but big storage is there, and it's been up and running 24/7 > > for 3+ years without any USB key incident... > > The difference is the fs. Ext3 uses a journal which uses always the same > physical sectors on disc. If the disc is a hard disk, it does not matter, > rewrites are no problem for platters. If it is an modern SSD, the SSD- > controller takes care and redirects the writes to different physical > sectors. USB-sticks have no smart controller and so the writes hit > always the same physical sector, it's like burning a hole in the flash > chip. If the commit time is standard for desktops set to 5 seconds, then > a whole year means a lot of writes to the same sector on an USB-stick.
Are you sure that modern, high quality USB sticks don´t do any wear leveling? On some SD cards there is some FAT optimizition in place[1][2]. I.e. good random access at beginning of drive, where FAT table and thus random I/O metadata accesses are. Ext3 places metadata elsewhere - I believe in about the middle of the partition. [1] Flash memory card design, FAT optimization https://wiki.linaro.org/WorkingGroups/KernelArchived/Projects/FlashCardSurvey [2] Arnd Bergmann, Optimizing Linux with cheap flash drives https://lwn.net/Articles/428584/ -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
