/tmp, /var/log, /var/tmp as /dev/md - why?
Mattia Rossi
mattia.rossi.mate at gmail.com
Thu Jul 3 06:20:23 UTC 2014
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 at gmail.com Tue Jul 1 11:37:35 2014
>>> 2014-07-01 11:25 GMT+02:00 Anton Shterenlikht <mexas at bris.ac.uk>:
>>>
>>>> Why is it a good idea to mount /tmp and some var dirs on memory disks:
>>>>
>>>> root at 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 at 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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