On Thu, Nov 03, 2005 at 11:39:43AM +0000, Alan Hourihane wrote: > On Thu, 2005-11-03 at 22:20 +1100, Neil Brown wrote: > > On Thursday November 3, alanh@xxxxxxxxxxxxxxxxxxxx wrote: > > > > > > I mean "Load the kernel image from an md device" which is what it means > > > to me too. > > > > > > So, you go on to say that booting from raid5 almost certainly requires > > > bios support - so I'm back to needing the onboard Sil 3114 BIOS to > > > handle that and then get md/dmraid to sort the rest out - which gets > > > back to my original question on when device mapper would get RAID5 > > > support so that dmraid can handle the SIL RAID5 metadata. > > > > "device mapper" and "dmraid" are of course different things. > > One is a kernel subsystem, the other is a configuration tool. > > For dmraid to be able to handle SIL RAID5, it is not necessary for > > "device mapper" to get RAID5 support, only for dmraid to have > > appropriate access to some sort of raid5 support in the Linux kernel. > > > > I would like md/raid5 (which is quite separate from device mapper) to > > be able to provide the required level of support so that if the dmraid > > developers so chose, they could use it rather than needing a second > > raid5 implementation in the kernel. Hence my original question, asking > > "how md/raid5 can be made to be sufficient" for the needs for dmraid? > > So what exactly is Heinz working on if it isn't support for RAID5 in > device-mapper ? It is a RAID4 and RAID5 device-mapper target. > > > I suspect all it needs is to be able to interface with a user-space > > metadata handler, and possibly some extra configuration options to > > match the expected functionality of the SiL. > > The former I hope be possible by 2.6.16. The later I'm interested in > > advice on. > > I'll defer to Heinz to make that choice - he's a lot closer to the code. The device-mapper kernel subsystem aims to avoid multiple drivers for block device virtualization being implemented seperately in the Linux kernel by adding device-mapper targets as we go. Implementing a target for RAID4 and RAID5 is just the long term approach to get more mappings supported by device-mapper in order to minimize code duplication. > > Alan. > > -- > > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- Regards, Heinz -- The LVM Guy -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 Cluster and Storage Development 56242 Marienrachdorf Germany Mauelshagen@xxxxxxxxxx +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
