On Fri, Apr 23, 2010 at 09:50:33AM -0400, John Baldwin wrote: > On Thursday 22 April 2010 11:31:37 am Alexander Motin wrote: > > If ataraid(4) should be reimplemented in GEOM, then how exactly? One > > more separate RAID infrastructure in GEOM (third?) looks excessive. > > Reuse gmirror, gstripe,... code would be nice, but will make them more > > complicated and could be not easy for RAID0+1 (due to common metadata) > > and RAID5 (due to lack of module in a base system). > > Scott's view (which sounds good to me) is that GEOM should include a library > of routines for working with common transforms such as RAID1, striping, etc. > Each ATA RAID vendor format would then consist of a small GEOM module that > used the library routines to manage all the I/O and the bulk of the module > would be managing a specific metadata format. I remember that SCSI standard has support for xor read-modify-write operations in addition to normal read/write to reduce R5 latency and bandwith. I'm not sure if any devices actually support it, but I think this may be worthwhile for networked devices. -- B.Walter <bernd_at_bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.Received on Fri Apr 23 2010 - 12:04:05 UTC
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