Re: shared disks in domU

[matthew sporleder <msporleder%gmail.com@localhost>]

On Tue, Sep 8, 2009 at 12:26 PM, Steven M. 
Bellovin<smb%cs.columbia.edu@localhost> wrote:
> On Tue, 8 Sep 2009 18:17:12 +0400
> Victor Gamov <vitspec%gmail.com@localhost> wrote:
>
>> 2009/9/8 der Mouse <mouse%rodents-montreal.org@localhost>:
>> >>> Can anybody explain me how I can create shared RW virtual disk in
>> >>> two or more domU?
>> >> What you're doing won't work, and will likely corrupt the file
>> >> system and/or panic one or both of the machines.
>>
>> I see
>>
>> >> The only way I know to do what you want is to use something like
>> >> NFS.
>>
>> Yes. but I'll try to find other solution.
>>
>> > Actually, Victor got exactly what he asked for, a shared RW virtual
>> > disk.  What he didn't get was what he wanted, a shared RW
>> > filesystem. (The same issues would arise with any other form of
>> > direct sharing of the same piece of disk, from two initiators on a
>> > SCSI chain to sharing an iSCSI target to dual-ported hardware.  As
>> > you point out, in the current state of filesystems, the only option
>> > is to interpose a piece of software, such as an NFS server, as an
>> > aggregator between the hosts and the disk - and make the hosts
>> > aware of it, as NFS client code is.)
>>
>> iSCSI is good point to start
>>
> No, it isn't.  As der Mouse and I have pointed out, getting a
> read-write *disk* is easy, but you want a read-write file system.  I
> know of none on NetBSD; in fact, I know of none on any Unix-like
> system, though Linux has so many file systems it's quite conceivable
> there is one for it.
>


GFS (redhat), and Veritas (linux, windows, and solaris) are the two
players I've used for this in production before.

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

I don't know of anything for netbsd other than NFS, which is actually
a really good solution in my experience.  :)