FSCK doesn't correct file size when INCORRECT BLOCK COUNT is found

Bjorn Gronvall bg at sics.se
Thu Dec 6 09:29:55 PST 2007

On Thu, 06 Dec 2007 16:01:50 +0100
julien.bellang at free.fr wrote:

Hi Julien,

> 1) First some information about the file corrupted :
> In my case the Files System has the following characteristics
> - the write cache is activated on the hard drive
> - the SoftUpdate option is activated
> - the FS is mount with the default option noasync

Filesystems in general and UFS with soft updates in particular rely on
disks providing accurate response to writes. When write caching is
enabled the disk will lie and tell the operating system that the write
has completed successfully, in reality the data is only cached in disk
RAM. When the power disappears the data will be gone forever.
In order to avoid this problem you can turn off write caching, this
way the software knows if the write completed successfully or
not. Alternatively you may power your disks from batteries, multiple
power supplies with UPS:es or come up with some other hardware


  _     _                                           ,_______________.
Bjorn Gronvall (Björn Grönvall)                    /_______________/|
Swedish Institute of Computer Science              |               ||
PO Box 1263, S-164 29 Kista, Sweden                | Schroedingers ||
Email: bg at sics.se, Phone +46 -8 633 15 25          |      Cat      |/
Cellular +46 -70 768 06 35, Fax +46 -8 751 72 30   '---------------'

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