Ext3+ramdisk journaling problem

Ext3+ramdisk journaling problem

[Xin Zhao]

hi,

I used ramdisk as an ext3 journal and mount ext3 file system with
option data=journal. It worked fine and speedup the ext3 file system.
However, After I reboot the system and try to mount that ext3
filesystem,  the system reported:

mount: wrong fs type, bad option, bad superblock on /dev/hda2,
       or too many mounted file systems

This gave me a feeling taht the ramdisk is not a right journal
anymore.  Any solution to this problem? Also, how to ensure that the
journal stored on the ramdisk is committed to ext3 filesystem before
it is umounted?  Any commands to do this?

THanks in advance for your kind help.

Xin

Re: Ext3+ramdisk journaling problem

[Kyle Moffett]

On Apr 24, 2005, at 21:22, Xin Zhao wrote:
> hi,
>
> I used ramdisk as an ext3 journal and mount ext3 file system with
> option data=journal. It worked fine and speedup the ext3 file system.

Uhh, the whole point of a journal is that when the computer goes down
hard and doesn't have a chance to clean up.  If you put the journal on
a ramdisk, you might as well just mount it as an ext2 filesystem and
be done with it.  Without the journal _on_disk_ you get no data or
filesystem reliability advantages.  If you're after speed, just forgo
the reliability or buy better disks.

Cheers,
Kyle Moffett

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------END GEEK CODE BLOCK------

Re: Ext3+ramdisk journaling problem

[Helge Hafting]

Kyle Moffett wrote:

> On Apr 24, 2005, at 21:22, Xin Zhao wrote:
>
>> hi,
>>
>> I used ramdisk as an ext3 journal and mount ext3 file system with
>> option data=journal. It worked fine and speedup the ext3 file system.
>
>
> Uhh, the whole point of a journal is that when the computer goes down
> hard and doesn't have a chance to clean up.  If you put the journal on
> a ramdisk, you might as well just mount it as an ext2 filesystem and
> be done with it.  Without the journal _on_disk_ you get no data or
> filesystem reliability advantages.  If you're after speed, just forgo
> the reliability or buy better disks.
>
Alternative: Buy a real ramdisk with battery-backup instead of using
a "ramdisk" in system ram.  Such a thing will last across a reboot,
offering both nice speed and all the comforts of a journal.

Helge Hafting