bugs

linux 系统控制硬盘旋转和停止的程序（spin down/up）

BUGS and LIMITATIONS

* Works only for IDE, SCSI requires a kernel patch.

* Journaling filesystems like ext3 or reiserfs bypasse the kernel's delayed
  write mechanisms and write straight to disk. Therefore noflushd is unable to
  postpone writing of journaling data. As a result, expect lousy spindown
  behaviour when working off ext3/reiserfs/jfs/xfs/... partitions. Fixing
  the issue requires a) a kernel change to make the journal's update interval
  configurable, and b) a new noflushd release to make use of the new feature.
  a) is on the ext3 folks' todo list, b) will have to wait for a).

* Doesn't work on kernel version 2.3.99pre8 to 2.4.0-test8 due to a format
  change in /proc/stat.

* noflushd, heavy swap activity, and APM suspend obviously don't go together
  too well. Upon resume, syslogd has a tendency to get stuck in 'D' state.
  Reportedly, noflushd and kupdate are up and running though, so I suspect
  this might be a kernel bug rather than a noflushd one. The best kludge I
  know of (thanks to Tom Holroyd) is to put a line with
    sync && sync && sync
  in the apmd suspend script.

* Calling sync with no dirty buffers pending will cause the disk to
  spin up but leave kupdate stopped (noflushd is still in spindown mode). 
  kupdate is restarted on the next read or write request though.

* Remounting a partition from read-only to read-write while noflushd's internal
  syncer is active will go unnoticed, i.e. no sync will occur. (This should be
  extremely rare - it requires that not only were e.g. /dev/hda{1,2...} all
  read-only before, but also the full disk device /dev/hda. A filesystem on
  an unpartitioned disk is probably the only real-world case where this bug
  might trigger.)

If you encountered a misfeature that isn't listed here, please use the bug
reporting system of your distribution, the noflushd bug tracker at the
SourceForge project page at http://sourceforge.net/projects/noflushd, or
send an e-mail to [e-mail].