On 6/22/2012 9:53 PM, Adam Goryachev wrote: > Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx> wrote: > >> On 6/22/2012 5:41 AM, Adam Goryachev wrote: >>> I have expanded my system over time, I started with 2 x 2TB drives in >>> RAID1 (md2) >>> >>> I then added 2 x 750GB drives, configured as RAID1 (md1) >>> Then created a third raid (md3) as linear with the md2 + md1 >>> >>> Finally, I've upgraded the 2 x 750G to 2 x 1TB drives (one at a >> time). >>> >>> I then did a mdadm --grow to expand the RAID1 from 750G to 1TB >>> >>> The problem I am having is that I can't expand the linear (md3) array >> to >>> grow the extra 250G of space. >>> >>> Could anyone suggest how I might be able to get the extra 250G of >> space >>> to become available? >> >> If you think about this for a few minutes more, and re-read how md >> --linear works, and thus how growing a linear array works, you'll >> surely >> understand why you can't do what you're attempting to do. > > Actually, no I don't understand the problem... From my (probably limited) understanding, linear simply appends each drive to the array. I understand that you would not be able to increase the size of any constituent device which is not the last component of the array, but I don't see any reason why it is not possible to increase the size of the last component. (Which is what I am attempting to do) > >> As for seeing that extra 250GB, I don't have an answer. Typically >> linear arrays are used in lieu of growing constituent member arrays. >> That's kinda the whole point of linear (concatenation). > > Well, the only other alternative I can think of is to reduce the size of the array back to 750G, reduce the size of the partitions for that array to 750G. Then create a new 250G partition on the two 1TB drives, create a fourth RAID1 array, and then add that 4th RAID1 array to the end of the existing linear array. This just didn't seem like a very good solution (ie, not clean). This is the only sure fire way I see ATM to do this. But I agree, it's not very clean. I'm a big proponent of only one array per physical disk, as I stated recently, and the reasons for it. Given what I'm guessing your workload profile is, it wouldn't make a difference. >> You could try deleting the linear array and simply creating a new one. >> But surely the changed offsets would wreak havoc on the filesystem >> currently spanning this mess. > > Perhaps this would work. If I delete the linear array and re-create, with assume-clean (or whatever the right flag is, I'll read the man page later when I'm doing it), then like I said, the first component device will be the same, the second component device is the same, but just happens to be bigger. Any comments on whether this should work? > > What should I do to ensure that the component devices are ordered the way I think they are? Apparently the numbers in /proc/mdstat just tell me what order the devices were added, not what order they are in the array? > > Thank you for your advice. The best advice I can give you is to wait for Neil Brown to weigh in before you make any such changes. -- Stan -- 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
