Messages in this thread | | | Subject | Re: The missing RAID level | From | Junio C Hamano <> | Date | Wed, 21 Apr 2004 14:52:30 -0700 |
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>>>>> "HT" == Hubert Tonneau <hubert.tonneau@fullpliant.org> writes:
HT> So, one very interesting possibility would be to have an HT> extra RAID level that would do the following:
HT> assuming that you connect 5+1 partitions, then you get 5 md HT> partitions, not a single one, with the following properties:
HT> . any read to mdX goes straight forward to reading the HT> underlying partition.
HT> . any write goes staight forward to writting the underlying HT> partition, but also updates the parity on the extra HT> partition.
It seems to me that you can create a single RAID-4 device out of 5 data and 1 parity disks, and run device mapper on top of that RAID-4 device, picking every 6 chunk worth of data and collecting into a device (totalling 6 devices). The first 5 such device mapper devices would end up with blocks from the underlying 5 data disks. I do not know offhand if such a dm target already exists, though.
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