[Aoetools-discuss] Re: exporting a disk read only with vblade ?

[Paul I. <i_p...@ya...>]

On Fri, 18 Mar 2005 12:37:17 -0500, Ed L Cashin wrote:

> Paul Ionescu <i_p...@ya...> writes:
> 
>> Hi,
>>
>> Does AoE support read only devices ?
> 
> It doesn't say anything about it.  It provides a way to put ATA commands
> on the network, but it doesn't mandate what the storage device has to do
> when it gets the ATA commands.
> 
>> Is is possible to export a read only device with vblade ?
> 
> If the vblade ignored ATA write and write-extended commands, then it would
> effectively be exporting the storage read only.

I think that just ignoring the write and write-extended commands will not
be enough, but we need to send back an write error.
Otherwise, the system thinks that it actually wrote a file when in fact it
did not.
Well, I can try this to see what happens.

>> I know that I can mount the underlying file system read only, but this
>> is not at device level.
> 
> Well, if you hack the vblade to make it able to export storage read only,
> then I'd be interested to know how specific filesystems react.
>
> I mean, are we sure that no filesystem will attempt to write to the
> storage if the filesystem is mounted read only?  If the vblade prints a
> diagnostic on write attempts, then it would be clear.

Yeah, this could be done.