Block device over network from Linux to FreeBSD

[Eric Anderson]

Martin Cracauer wrote:
> All right, here's a question that'll make your IQ drop by 5 points
> just from pondering it :-)
> 
> What's the best way to provide, over the network, a block device on
> harddrives that live on a Linux box and "export" them to a FreeBSD
> machine? Aka I want a FreeBSD filesystem on harddrives that are
> physically in a Linux box.
> 
> Long story:
> 
> My backup strategy is a FreeBSD filesystem with snapshots on a bunch
> of harddrives that live on networked computers in the basement.  All
> these computers boot diskless or disky into a variety of OSes, usually
> Linux or FreeBSD.  It would be easy to just use ext2fs or another
> filesystem supported by both, but I'd really like ufs2 snapshots.  So
> I need to access the disks in a box running Linux as a block device
> from a machine running FreeBSD.  When the machine having the physical
> disks runs FreeBSD I want to access the same raw devices directly, of
> course.
> 
> The brute-force approach would be:
> - ext2fs on disks
> - files inside ext2fs for use via mdconfig (and ccd)
> - then, depending on OSes booted, either:
>   - export via NFS and mdconfig on NFS mounts on remote FreeBSD machine
>   - direct FreeBSD mount (machine runs FreeBSD)
> 
> Another alternative I see is VMware or if any of the free emulators
> can boot FreeBSD on Linux and use the disks directly in the guest OS.
> 
> Linux has a network layer for block devices:
> http://www.it.uc3m.es/ptb/nbd/ . On first sight, it doesn't look too
> exiting nor does it look straightforward to implement a client in
> GEOM.  It uses daemons on both ends, so failover will not exactly be
> an improvement over NFS.  At least with NFS you know that a lot of
> other people depend on what you write being delivered eventually.
> 
> Then there's ATA over Ethernet as an established protocol.
> 
> Any other ideas?
> 
> USB'ing the harddrives is not considered sportish :-)
> 
> Martin


iSCSI?


Eric