Date: Thu, 03 Jul 2014 08:20:17 +0200 From: Mattia Rossi <mattia.rossi.mate@gmail.com> To: Anton Shterenlikht <mexas@bris.ac.uk>, rene@freebsd.org, freebsd-arm@freebsd.org Subject: Re: /tmp, /var/log, /var/tmp as /dev/md - why? Message-ID: <53B4F621.3040306@gmail.com> In-Reply-To: <20140702022042.GG45513@funkthat.com> References: <CADL2u4g65eo=7xxAt9j8JumyWneouhM2MGpcA9kfxJaCFWg95Q@mail.gmail.com> <201407011046.s61AkJpj006890@mech-cluster241.men.bris.ac.uk> <20140702022042.GG45513@funkthat.com>
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On 02/07/14 04:20, John-Mark Gurney wrote: > Anton Shterenlikht wrote this message on Tue, Jul 01, 2014 at 11:46 +0100: >> >From r.c.ladan@gmail.com Tue Jul 1 11:37:35 2014 >>> 2014-07-01 11:25 GMT+02:00 Anton Shterenlikht <mexas@bris.ac.uk>: >>> >>>> Why is it a good idea to mount /tmp and some var dirs on memory disks: >>>> >>>> root@raspberry-pi:/usr/ports # df -m >>>> Filesystem 1M-blocks Used Avail Capacity Mounted on >>>> /dev/mmcsd0s2a 14694 777 12742 6% / >>>> devfs 0 0 0 100% /dev >>>> /dev/mmcsd0s1 16 3 13 20% /boot/msdos >>>> /dev/md0 28 4 22 16% /tmp >>>> /dev/md1 14 0 12 0% /var/log >>>> /dev/md2 4 0 4 0% /var/tmp >>>> root@raspberry-pi:/usr/ports # >>>> >>>> Is this about speed or power, or maybe space? >>>> >>>> Mostly write tear because you're using an SD card, and it improves speed >>> too. >> "write tear"? >> Is this a joke, or some technical term? >> I cannot find what it means. > it is a technical term, though I'd be surprised if any SD card had > an issue w/ that anymore... > > write tear is where when writing data, only part of the data gets > written and then you loose power... This is mostly an issue on flash > where you have to erase the data beforey ou can program it... Most > flash now have a layer of indirection so that they copy/write the > data to a new flash block, and then point the block there before > erasing the old data... (kinda like a log FS)... > > Something like this will happen once your SD card is weared off.... grmbl: (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 19 5c 26 00 00 80 00 (da0:umass-sim0:0:0:0): CAM status: SCSI Status Error (da0:umass-sim0:0:0:0): SCSI status: Check Condition (da0:umass-sim0:0:0:0): SCSI sense: MEDIUM ERROR asc:30,0 (Incompatible medium i nstalled) (da0:umass-sim0:0:0:0): Retrying command (per sense data) (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 19 5c 26 00 00 80 00 (da0:umass-sim0:0:0:0): CAM status: SCSI Status Error (da0:umass-sim0:0:0:0): SCSI status: Check Condition (da0:umass-sim0:0:0:0): SCSI sense: UNIT ATTENTION asc:28,0 (Not ready to ready change, medium may have changed) (da0:umass-sim0:0:0:0): Retrying command (per sense data) g_vfs_done():da0s2[WRITE(offset=799834112, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=799965184, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800096256, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800227328, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem softdep_deallocate_dependencies: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800391168, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=800522240, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=800653312, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=800391168, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800522240, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800653312, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800817152, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=800948224, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801079296, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801210368, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801341440, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801472512, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801603584, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801734656, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801865728, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=801996800, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802127872, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem softdep_deallocate_dependencies: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802324480, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=802455552, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=802586624, length=131072)]error = 6 g_vfs_done():da0s2[WRITE(offset=802324480, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802455552, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802586624, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802750464, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=802881536, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803012608, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803143680, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803274752, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803405824, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803536896, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803667968, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803799040, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=803930112, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem g_vfs_done():da0s2[WRITE(offset=804061184, length=131072)]error = 6 /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem softdep_deallocate_dependencies: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem /: got error 6 while accessing filesystem softdep_deallocate_dependencies: got error 6 while accessing filesystem panic: Bad link elm 0xc5418700 prev->next != elm KDB: enter: panic [ thread pid 62848 tid 100082 ] Stopped at kdb_enter+0x4c: ldrb r15, [r15, r15, ror r15]! db>
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