Michal wrote, sometime around 11/11/09 11:40:
I know this is a bit off topic, but storage devices have battery's on
RAID cards for a reason. If you are worried about read/writes etc when a
system dies, there are measures you can take
Probably even more OT, but...
Although some (most?) RAID cards which have a battery option will only
let you enable the write cache if you have a battery installed.
Certainly the HP P400 cards we have do.
There has been endless discussion about data loss in these types of
scenarios on the XFS mailing list - it journals metadata but not data,
so if your application (e.g. vim) overwrites files by first truncating
them to 0 length and then writing out the data, you'll find that the
truncate and the resize of the file are all nicely replayed from the
journal after the crash, but if the machine died before your data hit
the disk, all you'll get when you read() is \0\0\0\0...
Since ext4 has started to implement similar features in similar ways to
XFS, the ext4 folk are running into the same old problems.
--
Russell Howe, IT Manager. <rh...@bmtmarinerisk.com>
BMT Marine & Offshore Surveys Ltd.
