Mount Ext3 under DragonFlyBSD

Donald Allen donaldcallen at
Sat Apr 28 05:50:16 PDT 2012

On Sat, Apr 28, 2012 at 12:35 AM,  <v_2e at> wrote:
>  Hello!
>  So can anybody give me some advice on this? Should I really delete
> the existing file system and create a new one with the 'sparse_super'
> flag off?

It's a bit difficult to help you without knowing what your overall
goal is. For example, how many machines are involved? Running what? Do
you want a filesystem that is mountable either by Linux or Dragonfly?
How big is the problem filesystem? Do you need to boot from it? If so,
which OS(es)?

Depending on your goals, you have plenty of options. If you no longer
have Linux available on the machine in question, you can run a live cd
version of Linux, such as Knoppix, to make a tar file of the existing
filesystem on a usb device of some sort (either flash or a disk if you
need the capacity; both are extremely cheap), either using a
filesystem that Dragonfly supports, or no filesystem at all. Once you
do that, you can reload the data with into any type of filesystem you
like, depending on what your requirements are.

Messing around with ext2 option flags is an extremely bad idea, unless
you backed up the filesystem first. Fortunately, whatever version of
Linux you were running wouldn't let you do something unsafe.

If your requirement is to share a filesystem between Linux and
Dragonfly, I'd be very careful to back it up. If you decide on an ext2
filesystem (Dragonfly doesn't support ext3, as far as I know), I'd be
wary of the Dragonfly driver. I've run into problems with BSDs talking
to my usb backup disks, which have ext2 filesystem on them. FreeBSD
had an outright bug that crashed the system repeatedly, fortunately
without loss of data. OpenBSD had extreme performance issues. NetBSD
wouldn't mount an ext2 filesystem with 256 byte inodes. In all cases,
I am not talking about the current versions. I'm simply warning you
that ext2 is not high on the priority list of any of the BSDs and the
BSDs in general are much more constrained than Linux in terms of
development resources. So back up your files (with Linux) early and
often if you are going to point Dragonfly at them.

/Don Allen

>  Thanks.
>    Vladimir
> On Fri, 6 Apr 2012 20:36:15 +0300
> v_2e at wrote:
>>   Hello!
>>   I'm new (well, actually, very very very new) to DragonFlyBSD and
>> currently doing my first steps with it.  I have Ext2 and Ext3
>> partitions on my HDD (created under GNU/Linux) and I cannot use them
>> under DragonFlyBSD. The problem is that when I try to mount any of
>> them, I get the following error message:
>>     # mount /dev/ad4s3 /mnt/data/
>>     mount: /dev/ad4s3 on /mnt/data: incorrect super block
>> Or if I state the FS type explicitly, I get this:
>>     # mount -t ext2fs /dev/ad4s3 /mnt/data/
>>     WARNING: R/W mount of #ad/0x40002 denied due to unsupported
>> optional features
>>     ext2fs: /dev/ad4s3: Invalid argument
>>   The only mode I can mount these file systems in is read-only mode.
>> However, the file systems are not usable in this mode either, because
>> I can only list the root catalog of the corresponding FS. Any attempt
>> to list other catalogs or read some files leads to the following
>> error message on the screen:
>> and a system reboot.
>> I searched over Internet for a similar issue and found only one sane
>> article mentioning this problem
>> ( ). Its
>> author tells that the root of the problem is the 'sparse_super' flag
>> set on the Ext2 file system and suggest to turn this flag off:
>>     tune2fs -s off /dev/sda3
>> I tried it under my GNU/Linux system, but it says only:
>>     Clearing filesystem feature 'sparse_super' not supported.
>> and does not do the job.
>>   So now I just do not know what to do. How cat I use my existing
>> Ext2/Ext3 file systems on DragonFlyBSD? Any suggestions?
>>   Thanks.
>>     Vladimir
>> -----
>>  <v_2e at>
> -----
>  <v_2e at>

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