Bill Davidsen wrote: > .. > I'm not clear on what you mean by a "plain disk" followed by a list of > partitions. If that means putting all your initial data on a single > disk without RAID protection, that's a far worse idea in my experience > than splitting arrays across controllers. It is easiest enough for now to mirror the boot drive. I worded it this way to make it clear the migration is not a booting issue. >> The remaining 15 disks are configured as : >> sdb1 through sde1 as md0 ( 4 devices/partitions) >> sdf1 through sdp1 as md1 (10 devices/partitions) >> I want to add a 2nd controller, and 4 more drives, to the md0 device. >> >> But, I do not want md0 to be "split" across the 2 controllers this way. >> I prefer to do the split on md1 >> > Move the md0 drives to the 2nd controller, add more. Yes, that is one way, involving some hardware swapping and more downtime. >> Other than starting from scratch, the best solution would be to add the >> disks to md0, then to "magically" turn md0 into md1, and md1 into md0 >> > > Unless you want to practice doing critical config changes, why? Moving > the drives won't effect their name, at least not unless you have done > something like configure by physical partition name instead of UUID. > Doing that for more than a few drives is a learning experience waiting > to happen. If that's the case, backup your mdadm.conf file and > reconfigure using UUID, then start moving things around. OK, where may I learn more on using UUID for drive identification? I have always assembled a RAID using the syntax /dev/sdxx ( sd drive letter and partition number) I take it there is a way to identify the UUID of a drive and partition and assemble and maintain using syntax that way? I hope that this will also get me past the problem sometimes of running out of letters in the 26 char alphabet! I never thought the day where I would have a problem with more than 24 drives.. OK, so I show my age there! > .. > Then consider the performance vs. reliability issues of having all > drives on a single controller. > Multiple controllers give you more points of failure unless you are > mirroring across them, but better peak performance. Controller reliability seems to be not an issue. I have rarely seen a 3Ware card fail. Drives, OTOH, well.. Hence the desire to have duplicated arrays, so we can clone across on MD to another. > Note, I'm suggesting evaluating what you are doing only, it may be > fine, just avoids "didn't think about that" events. > Agreed. All good points. > Well, you asked for suggestions... ;-) These are appreciated. I am still looking , however, for a way to rename and md device. Another case where it comes up is when I take a set of drives from one machine and move them to another. Having conflicting md devices comes to mind.. Thanks Bill -- With our best regards, Maurice W. Hilarius Telephone: 01-780-456-9771 Hard Data Ltd. FAX: 01-780-456-9772 11060 - 166 Avenue email:maurice@xxxxxxxxxxxx Edmonton, AB, Canada http://www.harddata.com/ T5X 1Y3 - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
