On Wed, Jun 27, 2007 at 10:46:49AM -0700, Gaston, Jason D wrote: > >-----Original Message----- > >From: Heinz Mauelshagen [mailto:mauelshagen@xxxxxxxxxx] > >Sent: Tuesday, June 26, 2007 12:58 AM > >To: Gaston, Jason D > >Cc: mauelshagen@xxxxxxxxxx; ATARAID (eg, Promise Fasttrak, > >Highpoint 370) related discussions > >Subject: Re: raid10 vs raid01 type in dmraid > > > >On Mon, Jun 25, 2007 at 10:18:14AM -0700, Gaston, Jason D wrote: > >> > > >> >Eg, PC Magazine: > >> >"RAID 10, RAID 100 - Speed and Fault Tolerance > >> >RAID 10 is RAID 1 + 0. The drives are striped for performance > >> >(RAID 0), and all striped drives are duplicated (RAID 1) for > >> >fault tolerance." > >> > > >> >Yes, I konw, there's different (aargh!) definitions out there. > >> > > >> >Like I said: the top -> bottom of the stack definition is preferable > >> >to me (you reach the mirror first and the stripe second > >while walking > >> >the stack from the top to the bottom). > >> > > >> >We just got to hold on to one definition in dmraid, > >> > > >> >Heinz > >> > > >> > >> Ok, so the dmraid definition is not going to change. > > > >I'ld much rather avoid it :-) > > > >> > >> Do you see an advantage in putting the RAID1 vs. RAID0 on > >the bottom for > >> being able to perform rebuilds easier? I need to decide > >which way to do > >> with isw. > > > >Talking about either a mirror on top of stripes or a stripe on > >top of mirrors, > >it is merely a question of IO minimization on rebuilds. > > > >Ie. when a stripe below a mirror breaks, you've got to > >resilver the whole > >stripe set, hence writing 2 or more drives rather than just one disk in > >a mirror set beneath a stripe. > > > > > >With respect to ease of rebuilds at the programming level, there's no > >difference in changing the mapping of a top level mirror to do a full > >resync vs. a bottom level mirror. > > > > > >Getting back to your decision: you could support both ;-) > > > >Cheers, > >Heinz > > > >> > >> Thanks, > >> > >> Jason > > > > After adding support for RAID10 to isw.c, what will we need to do in > order for this to be supported in anaconda, so that we can install to a > RAID10 nested volume? I don't see support for nested RAID levels in > dmraid.py. This is merely a mkinitrd issue: we want to change mkinitrd to make initrd call dmraid directly rather than using static tables for multipath, mirroring, dmraid, .... With that solution, RAID10 *should* just work with anaconda. Please talk to Peter Jones (pjones@xxxxxxxxxx) about details. > > Thanks, > > Jason -- Regards, Heinz -- The LVM Guy -- *** Software bugs are stupid. Nevertheless it needs not so stupid people to solve them *** =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 Storage Development 56242 Marienrachdorf Germany Mauelshagen@xxxxxxxxxx PHONE +49 171 7803392 FAX +49 2626 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _______________________________________________ Ataraid-list mailing list Ataraid-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ataraid-list
