>>> Mount it with a loop device.
>>
>> Random, but... why the hell do you need a loopback "device" in the 
>> first place? Why can't you just mount (say) an ISO image directly? 
>> Requiring a loopback device means that
>>
>> 1. there are only a finite number of them available,
> 
> Have a look at this document:
>   http://www.slax.org/documentation_loop_mount.php
> 
> Here's how I understand the situation:
> 
> Linux kernels earlier than v. 2.6.23 had 8 loop devices, unless you 
> specified more
> Linux kernel v. 2.6.23 had 256 loop devices
> Linux kernel v. 2.6.24 and later does not have these limitations

The device files still have to exist in the filesystem though. (That's a 
fairly bizare concept in itself...)

>> 2. before you can mount anything loopback, you have to determine which 
>> device numbers (if any) are free.
> 
> Just try this:
> 
>   mount -o loop,offset=somenumberofbytes ~/sda.img /mnt/sda1
> 
>  From the mount manual:

> is given), then mount will try to find some unused loop device and use 
> that."

So somebody wrote the code to automatically select a free device. The 
fact is, you still need there to be a free device. I still don't get why 
you can't just mount the file itself...

Post a reply to this message

Invisible wrote:
>>>> Mount it with a loop device.
>>>
>>> Random, but... why the hell do you need a loopback "device" in the 
>>> first place? Why can't you just mount (say) an ISO image directly? 
>>> Requiring a loopback device means that
>>>
>>> 1. there are only a finite number of them available,
>>
>> Have a look at this document:
>>   http://www.slax.org/documentation_loop_mount.php
>>
>> Here's how I understand the situation:
>>
>> Linux kernels earlier than v. 2.6.23 had 8 loop devices, unless you 
>> specified more
>> Linux kernel v. 2.6.23 had 256 loop devices
>> Linux kernel v. 2.6.24 and later does not have these limitations
> 
> The device files still have to exist in the filesystem though. (That's a 
> fairly bizare concept in itself...)
> 
>>> 2. before you can mount anything loopback, you have to determine 
>>> which device numbers (if any) are free.
>>
>> Just try this:
>>
>>   mount -o loop,offset=somenumberofbytes ~/sda.img /mnt/sda1
>>
>>  From the mount manual:


>> and use that."
> 
> So somebody wrote the code to automatically select a free device. The 
> fact is, you still need there to be a free device.

If your kernel is of a newer version there will always be a free loop device,
I.e. you don't have to worry about that.


> fact is, you still need there to be a free device. I still don't get why 
> you can't just mount the file itself...

Because the file is not a block device.

   http://en.wikipedia.org/wiki/Loop_device

-- 
Tor Olav
http://subcube.com

Post a reply to this message

>> I still don't get why you can't just mount the file itself...
> 
> Because the file is not a block device.

I thought the whole idea of the "device file" abstraction is that 
accessing an entire device is no different from accessing a regular 
file. And, if that's the case, you'd expect storing a filesystem inside 
a file to be no different than storing a filesystem on a device.

And yet, it *is* different - one automatically works, the other requires 
you to jump through hoops. Or, loops, in this case...

Post a reply to this message

Invisible wrote:
> The device files still have to exist in the filesystem though. (That's a 
> fairly bizare concept in itself...)

It's legacy.


-- 
   Darren New, San Diego CA, USA (PST)
   There's no CD like OCD, there's no CD I knoooow!

Post a reply to this message

Darren New wrote:
> If you really want to know why someone would pay money for the product,
> look at the page on wikipedia to see the list of features it would be a
> PITA to put together under Linux. For *some* people, time is money. :-)

I guess I currently have more time than money :D

That's a reason why teenagers pirate too. They have more time to try
multiple super-complicated DRM-cracking programs till they get it to work
than they have money to buy a genuine copy.

Post a reply to this message

Invisible wrote:
> 2. before you can mount anything loopback, you have to determine which
> device numbers (if any) are free.

Uh, no.

mount -o loop file.iso mountpoint

Post a reply to this message

Nicolas Alvarez wrote:

> That's a reason why teenagers pirate too. They have more time to try
> multiple super-complicated DRM-cracking programs till they get it to work
> than they have money to buy a genuine copy.

Oh... really? I thought it was because teenagers think they have a 
*right* to get whatever they want. (Or possibly becuase they have no 
money.) Guess I was wrong... again.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Darren New wrote:
> Invisible wrote:
>> The device files still have to exist in the filesystem though. (That's 
>> a fairly bizare concept in itself...)
> 
> It's legacy.

I'll say...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Darren New wrote:
> None of this lets you restore to a partition of a different size or 
> backup only the used sectors, or browse the files in the backup over the 
> network without decompressing them.
> 
> It also doesn't let you clone a new Windows machine from an old one.

Hmmm... Do many companies put themselves in situations that demands such 
features ?

-- 
Tor Olav
http://subcube.com

Post a reply to this message

Darren New wrote:
> Tor Olav Kristensen wrote:
>> When you are finished, it would be wise to boot from a Knoppix CD
>> and connect an external USB HD (sdb) and do this in order to
>> backup your whole Win NT disk:
> 
> Or you could use the free DriveXML that walks you thru the process, 
> saving only the space occupied by files, compressing and/or splitting 
> the result, and restores just as easily. :-)

Ok, but what is the procedure then for using DriveXML to restore a 
system that will not boot ?

-- 
Tor Olav
http://subcube.com

Post a reply to this message