ext3 fun , slow writing speed ????

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I have a silly problem, my hard disk structure is shown below. my
application is writing a lot of data (25+ frames per seconds) on a
read-write partition hda3 all the time.

Hda1 – swap (128MB)
Hda2 – ext2  ( 400MB) Read - Only
Hda3 – ext2  (58GB)

On site system always switch off from mains so no unmounting.
And next time when we switch it on it get stuck in fsck for manual
check.

I tried converting ext3 to solve this problem, things works fine it
don't stuck for manual fsck but very unusual thing happens.

My writing speeds of the frames to disk drops down to half…

I have no idea why this happens.


It gives me message file system is already journal when I try to do
tune2fs –j, so I change the fstab to ext3 and it works fine except the
writing speeds????


Any suggestions ?????????

Thanks

Rushi

Re: ext3 fun , slow writing speed ????
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Ext3 will *not* save your filesystem from corruption and having to do
a manual fsck.  All it does is *reduce the likelihood* of a catastrophic
filesystem error if you switch off the power.  You will still *inevitably*
get a catastrophic filesystem error sometime if you switch off the
power to a writing system.  If, as you are doing, you are writing a lot
of data all the time, then it'll happen sooner or later.  If this in not
accpetable in your application, you can only change the hardware so that
you get some warning that power is about to go off, and shut down or
at least unmount the drive cleanly.  Consider a UPS that can talk to your
box.

AFAIK there is no (linux) filesystem that can guarantee not to corrupt if
power is removed, although I suppose you could design one if you are prepared
to accept data loss.

--
Trevor Barton

Re: ext3 fun , slow writing speed ????
Thanks Trevor,

I think got to implement something from ACPI, not sure yet if my SBC
support the protocol or not.

But for the current system I am not worried about the corrupt data
much , I just want to stop the system going to manual fsck and scan it
automatically if it goes in that mode




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Re: ext3 fun , slow writing speed ????
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If you really don't care about data saving over a powerup at all, just
make a partition with nothing else on it and reformat it each boot by
not mounting it automatically from your fstab and then running
mke2fs later in the init script somehwere.

Alternatively, you can probably do the same thing (ie leave it unmounted)
and run fsck later with some combination of flags that'll do everything
it can automatically as return some error code to the shell if the disk
is damaged beyond repair, at which point you can reformat.  Look at the
man page for fsck.

The boot process only stops and demands a manual fsck because you have
the partition being mounted automatically as part of the boot process,
and it's determined that the partition is sufficiently brken that
it doesn't want to automatically fix it for you, in case it's the
wrong thing to do.

Stop that hapenning (through /etc/fstab) and you can then do what you
want with it later.

Trev

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--
Trevor Barton

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