>i just started to investigate how biosraid support for the HPT37X >IDE-chipsets can be implemented in the 2.6 kernel. implementing the >basic raid levels (0, 1, 0+1, JBOD) seems to be pretty straight forward. >this can be done by reading the raid signatures of the disks and then >pipeing the configuration through dmsetup or using the libdevmapper >library directly. what bothers me is the partition support. the number >of minor device nodes that are registered per mapped block device is 1. >this means that there is no way that the kernel does the >partition-handling by itself. the alternative is to do the partition >scanning in userspace and to use another device mapper layer to create >the partition device nodes. it appears that this was already suggested >by Christophe Varoqui ( http://lwn.net/Articles/13958/ ) but this >project is now idle. this also has the disadvantage that any changes in >the partitioning of the raid volume (e.g. by using *fdisk, distribution >installers, ...) require a manual re-invocation of the biosraid setup >tool. plus the whole code under linux/fs/partitions/... has to be >duplicated so that not only the dos partitioning scheme is supported, >but also BSD slices, x86 solaris, windows dynamic disks, ... Sounds like you should look at the EVMS activate command. EVMS can already recognize and activate/reactivate: os/2, dos, bsd (compatible and dedicated), solarisx86(embedded), unixware(embedded), 390 (cdl,ldl,cms), mac, cluster and bbr partitions throught its device mapper interface. -Don