Matthias Apitz wrote: > El día Thursday, December 08, 2011 a las 09:57:13AM -0600, Dan Nelson > escribió: > > > Cheap USB thumb drives aren't really optimized for small random-I/O writes. > > Can you try mounting the filesystem async? that might help a little. A > > workaround would be to use mdconfig to create a block device (backed by > > either swap or a file on your hard drive) the same size as your flash drive, > > newfs and restore to that, then umount the filesystem and dd the raw image > > directly to your flash drive. > > Hello Dan, > > Thanks for your hints. I tend to add that those USB thum drives aren't > good for anything. I have a certain number of them containing each a > complete bootable FreeBSD (including 'src', 'obj' and binary packages) > to install my laptops and netbooks from them; > > after some time these USB keys tend to loose data: > files are corrupt a bit, dirs are missing and so on; that's > why I wanted to make dump(8) nackups of them, to restore them from time > to time; I will drop the idea and will just make dd(1) backups of the > full /dev/da0;
Additional to all the other good points others wrote earlier, may I mention: ... I've found some sticks are slower than others. Sometimes I do a performance & integrity test with my http://berklix.com/~jhs/src/bsd/jhs/bin/public/testblock One (free promo) stick I found lies, see this comment in my http://berklix.com/~jhs/src/bsd/fixes/FreeBSD/src/jhs/etc/devd/jhs.conf # The end of it is write only memory ! # It lets one write the last chunck, # It even lets one read that last chunk, # but the content of the last chunck is all zeroes. Another 2G stick was particularly slow: (marked as) Sony, bought at a computer Sunday 'flea' market in Croydon England, in retrospect I wonder if manufacturer Sony might have withdrawn them from sale, marked the batch for destruction, & possibly some criminal 'liberated' them for resale again ? (Such things do happen, eg In Germany years back, pre USB era, CT Mag reported reported Betruger/Placebo cache chips. They were just ceramic with no silicon in, it was reported importers (in Munich I think) were afraid to sue chinese exporters, fear of Triads! maybe last bit was speculation, but wan't My speculation, I read it, whatever, can't remember more now) Block Sizes: Maybe USB sticks may have different size/ speed front end cache chips on USB sticks ? Hans would know I suppose. ? Apart from soft updates, one can also choose the block sizes newfs creates, I recall FFS is larger than UFS ?. Maybe we should send-pr some suggested size for man newfs if targeting images for USB sticks. (is that a question to consider jointly with fs@ list ? ) Voltages: I've recently been bitten by appalling problems on a bunch of 2 of my externals discs, using 2 different laptops, 2/3 hubs, & 3 power supplies. Various combinations come back to bad voltage regulation, usually too low, some too high. But I assume discs will be more susceptible than sticks. However next time a motherboard fails for any of you, I suggest don't discard, first hacksaw off the double USB socket, solder wires across, add extra wires for a meter, so you can monitor voltage & current. Mastering first on hard disc (per Dan's suggestion, mdconfig etc) is a good idea, I was considering this earlier when building a new stick/ extended Live-FS. .. using mdconfig etc, but it's heavy & slow after the initial image create, to keep rewriting, even if at large dd bs= So I use incremental writes I keep personal backups & bins & Live FS & mp3 to play etc all on USB sticks. Still usable though 'cos I rarely change too much at one time. & rdist6 updates what's changed. (would also correct odd corruption Matthias) I even sue gbde encrypted FS (ie more performance degradation) .. and updates still happens acceptably if not exactly fast. Others could use rsync if they dont fancy rdist6. Cheers, Julian -- Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com Reply below not above, cumulative like a play script, & indent with "> ". Format: Plain text. Not HTML, multipart/alternative, base64, quoted-printable. _______________________________________________ email@example.com mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "freebsd-usb-unsubscr...@freebsd.org"