Hi Bruno, Please find attached a patch that implements mdadm support whilst fully retaining raidtools2 support. With the changes detailed in the patch, I have just successfully archived and restored a RAID1 and a RAID0 array consisting of two drives each on Debian sid amd64, but I expect all Linux distribution with mdadm to work as well (famous last words ;-) ).
A few notes and remarks: After much going back and forth I have decided to extend what is already there rather than recode much of the RAID functionality. The reasons are mainly that I have only limited time and wanted results rather sooner than later but even more so that I didn't want to change the raidtools2 side of things because I can't/won't test this and I didn't want to spend any effort on raidtools2 because it's officially deprecated (cf. http://people.redhat.com/mingo/raidtools/). With this said, the patch utilises existing capabilities for parsing /proc/mdstat and for reading and writing /etc/raidtab. mdadm works without a config file and even 'mdadm --detail --scan --verbose' does not give all the (relevant) information that can be gathered from mdstat. I could have come up with a new file (format), but I think raidtab is fine (it shouldn't be in /etc really). I am introducing a new function create_raid_device_via_mdadm() that will create a single RAID array using mdadm and that gets called in format_device() in case mkraid cannot be found. Same goes for 'mdadm -S' versus raidstop. An equivalent for raidstart is not really required as 'mdadm --create' starts the array straight away. There are limitations (pre-existing, not introduced by my changes): - chunk size is hard coded to 4k - spare devices are ignored - the parity algorithm is ignored - multipath is not supported To overcome these limitations, I will need to change some data structures and expand the mdstat parser - in fact, I have already written an experimental stand-alone parser for this purpose. I'm not sure whether multipath is worth it; it is not even really a RAID level. Further, I had to include a few more modules for RAID in mindi and init needed a little change. Finally, device mapper is not supported. I understand you are working on this, so I haven't looked into it. It would be great if you could let me know what you think, in particular whether you'd be sufficiently happy for this to go into the next stable version. Cheers, Andree -- Andree Leidenfrost Sydney - Australia
RAIDpatch#325877v1.tar.gz
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