Trying to add sync option to root mount

lbuccola · 10-14-2011, 08:11 AM

I am running Debian Linux on an embedded ARM9. Buildroot was used to create the kernel. Kernel is 2.6.35.9. TimeSys was used to create the filesystem using glibc.

I boot from an SD Card. The first partition has the bootloader and kernel. Second partition is the filesystem. I have had a few field failures where the filesystem has become corrupt. I am trying to add the sync option to the root mount to lessen this possibility. No matter what I add to fstab it doesn't seem to matter. Root is never mounted with sync.

Here's my current fstab:

Quote:

/dev/root / ext4 rw,sync 0 1
proc /proc proc defaults 0 0
sysfs /sys sysfs defaults 0 0
tmpfs /tmp tmpfs defaults 0 0
none /dev/pts devpts defaults 0 0

Here's what mount returns after booting:

Quote:

rootfs on / type rootfs (rw)
/dev/root on / type ext4 (rw,relatime,barrier=1,data=ordered)
devtmpfs on /dev type devtmpfs (rw,relatime,size=62880k,nr_inodes=15720,mode=755)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
/dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,sync,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/mmcblk0p2 on /media/mmcblk0p2 type ext4 (rw,relatime,barrier=1,data=ordered)
tmpfs on /tmp type tmpfs (rw,relatime)

And here's what df returns:

Quote:

Filesystem 1024-blocks Used Available Use% Mounted on
/dev/root 1806120 195996 1518352 11% /
devtmpfs 62880 0 62880 0% /dev
/dev/mmcblk0p1 124634 2052 122582 2% /media/mmcblk0p1
/dev/mmcblk0p2 1806120 195996 1518352 11% /media/mmcblk0p2
tmpfs 62948 24 62924 0% /tmp

I have tried /dev/root, /dev/mmcblk0p2 and /rootfs and none of them show the sync option actually took.

Any ideas would be greatly appreciated.

cheesus · 10-14-2011, 12:54 PM

from man 8 mount:

Quote:

The following options apply to any filesystem that is being mounted (but not every filesystem actually honors them -
e.g., the sync option today has effect only for ext2, ext3, fat, vfat and ufs):

i.e. ext4 does not support it.

Cheers!

lbuccola · 10-15-2011, 08:14 AM

Thanks. As soon as I get back in the office on Monday I'll format my SD partition as ext3 and try. Kernel already has support for it so it's just a matter of a simple format and then untar the fiesystem to the SD card.