sorry, I meant daniel and all that are working with/on ddraid, Jakob Praher wrote: > > I am very interested in ddraid for having sios systems over the network. > A few questions though: > > I've looked shortly at your implementation (ddraid-0.5.0), but have a > few questions, which I thought to ask you: > > * how will you track extensibilty: > > afaik you assign a fixed number of logical sectors to the device mapper > device. but lets take a trivial example: > > you have 3 disks (2^k+1), each in a sperate computer. > then you want to plug a 4th and 5th disk (2^k+1) disk (again separate > computer) in the ddraid - how should that look like regarding the dm setup? > > what problems could arise given the striping information on the blocks. > do you simply extend a stripe from 2 to 4 data blocks? is it possible to > raise the number of logical sectors with device mapper (sorry for my > ignorance - I haven't looked the details of the dmsetup man page). do > you have to rearrange block sizes or stripe information? > > * have you investigated raid-x - would that be possible to implement via > device mapper? > > I've looked closer on a the papers by hwang et al regarding Raid-x, > which also provides a single io space for servlerless clusters. The > design is basically a mixture of mirroring and striping, making it > possible for one node to fail completly. > On stripe is made of (n-1) blocks and you have (n-1) mirror blocks. They > have implemented as part of their trojan cluster project, wich I think > isn't alive any more. > > I look forward to hearing from you. > > -- Jakob > -- Linux-cluster@xxxxxxxxxx http://www.redhat.com/mailman/listinfo/linux-cluster
