Here’s a quick tip on how to make an fsck (or specifically an fsck_hsfs) run much faster. I learned this as part of debugging some corruption with the backup image on my Time Capsule.
/bin/fsck_hfs -f -d -c {%mem} /dev/rdisk{N}
where {%mem} is ½ to 1⁄3rd the amount of memory you have in your computer. If you need to determine the amount of memory in a machine from the command line, a great blog post on Mac OS X Command Line Goodies suggests you can use:
/usr/sbin/system_profiler SPHardwareDataType | grep Memory
For example, you can use -c 512m if you have a 1GB machine.
and
{N} is the correct device node. This command will show you the list of disk nodes:
diskutil list
For example, you might use /dev/rdisk0s2.
The -d turns on debugging and -f instructs fsck_hsfs to force a repair if it finds any problems.
In case you were curious, the -c setting is the part of the incantation that gives it its real magic. It lets the command cache a considerable amount of information in memory and that speeds up any scan a tremendous amount. If you ever run a disk repair from Disk Utility, you’ll notice the fsck_hsfs command it spawns lacks this option and hence is much slower.
{ 0 comments… add one now }