two questions: 1) How does nbd deal with the differential latency issue? If latency differs by too much a RAID system will end up with stripes on different "disks" out of order, and things get REALLY messed up at that point. 2) What is RAID 6? Dan Lund wrote: > 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 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 >> >> >> >>--------------------------------------------------- >>PLUG-discuss mailing list - >>PLUG-discuss@lists.plug.phoenix.az.us >>To subscribe, unsubscribe, or to change you mail settings: >>http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss >> >> > > > > -- > To exercise power costs effort and demands courage. That is why so > many fail to assert rights to which they are perfectly entitled - > because a right is a kind of power but they are too lazy or too > cowardly to exercise it. The virtues which cloak these faults are > called patience and forbearance. > Friedrich Nietzsche > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us > To subscribe, unsubscribe, or to change you mail settings: > http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss > --------------------------------------------------- PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us To subscribe, unsubscribe, or to change you mail settings: http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss