hi philipp and all, 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
