"RAID" for remote filesystems

[Dan Lund]

I've done work like this with the network block device as an
experiment in several different ways.
To put it in a nutshell I had a machine exporting a couple of nbd
(network block devices), and I accepted them on another.  They showed
up as /dev/nbd/0, /dev/nbd/1, etc.
I then made a raidtab that took them and set them into a RAID5 and had
a hotspare.
I've tested it with RAID1/5/5+1/6/6+1, made it failover, hot-added
"drives", etc.

It was pretty decent in throughput, and I was about ready to put
together a turnkey solution for my work as an expandable disk
subsystem. (on it's own gig backplane)  I made sure it was on it's own
gig backplane because the nbd devices are solely dependant on the
network.  If it so much as blips, your disks go away.
RAID, as far as I know, only works on block devices.
You could always check out PVFS, or Coda if your looking for something
on the filesystem layer.  I have far more faith in nbd though.......

--Dan


On 10/9/05, Matt Alexander <lowbassman at gmail.com> wrote:
> I'm wondering if anyone knows if this is possible...
>
>  Take multiple remote filesystems such as NFS, gmailfs, Samba, sshfs, and
> layer a filesystem over the top to create one namespace.  Ideally it would
> provide some fault tolerance/redundancy and improved performance by using
> the concept of RAID over the multiple connections.
>
>  In reality, this new filesystem layer wouldn't care if the filesystems are
> remote or not.  You could have...
>
>  /mynfsmount
>  /mygmailfsmount
>  /myothergmailfsmount
>  /mysshfsmount
>
>  ...and then a new mount point of...
>
>  /myreallycoolmount
>
>  ...and when you put files here, they're striped/mirrored over all the
> previous mounts.
>
>  Is this currently possible?  If not, then perhaps I'll see if I can make it
> happen in my minuscule free time.  I know there are a ton of potential
> problems with this, but it'd be a fun project nonetheless.
>  Thanks,
>  ~M
>
>
>
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