Re: Have ext3 on SanDisk CF but can't disable write-back caching as kernel instructs
From: Edward Lee epl (me_at_linnix.com)
Date: 07/21/03
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Date: 21 Jul 2003 09:05:36 -0700
Michael Schnell <mschnell@lumino.de> wrote in message news:<3F1BA952.C63D16EE@lumino.de>...
> > What kind of idiot hardware engineer would design a
Probably one that got fired.
> > piece of hardware that only gives you 1 second or less write time in event
> > of a power failure, especially in a system that is guaranteed to have power
> > failures on a regular basis?
>
> It can't be fixed with software as it partly has nothing to do with it.
> IMHO the CF manufacturer does not guarantee that the card can cope with
> turning the power off a second after the last write access. First they
Not just the CF write time, also the file system sync. flush time. I
would put in at least one minute. Furthermore, the CPU needs to be
running on backup as well.
> need to find out _this_ specification. If it can't be determined you
> just can't us a CF. Than someone needs to define the time the software
> needs to clean up when power fail is detected. Adding the two is the
> time power needs to stay intact after the power fail signal.
CFs are designed for devices with auto power off, i.e. cameras. Of
course, if
you yank out the battery while taking picture, there is no guarantee
of the result. Using CFs for mission critical data storages will
never fly, as the OP attempted to do, or are forced to do so.
>
> -Michael
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