On Saturday April 7, rich@xxxxxxxxxxxxxx wrote: > Gavin McCullagh wrote: > > > > I must admit I've never used linear raid. May I ask what made you choose > > it over say raid-0? > > > Er, I went with Linear as reading around people seemed to recommend this > for odd sized drives (my old drives are 80's, 120 and 320's) also a read > somewhere that data on the other drives is more recoverable that most of > the other RAID's. Linux raid0 works with varying sized drives without problem. > > > >> First question, what happens if one drive fails (I know I will loose the > >> data on that drive) but how, if at all can I recover the data on the > >> other drives can I plug them in (on their own) as though they were in > >> fact an individual drives? Do I need to execute a rebuild command in > >> mdadm at all to rebuild the array? If you lose one drive, you should consider that you have lost the whole array. You might be able to recover some data, if you are lucky and spend a lot of time hunting for it. But it is quite unlikely that you will get much that is useful. > > > >> Second question, how can I go about adding a drive to my linear RAID, I > >> wish to add two new 500GB drives but I'm unsure how. I have found howto's > >> for RAID 5 but I just wanted to check it was a similar process for > >> Linear? Also this won't effect any data currently on the drive will it? > >> > > > > You don't say what you're doing on this array, but before modifying it, I'd > > be seriously inclined to question whether RAID-linear is really the right > > thing to be using at all. Anyway, the mdadm manpage says > > > > "Currently the only support available is to > > · change the "size" attribute for RAID1, RAID5 and RAID6. > > · increase the "raid-disks" attribute of RAID1 and RAID5. > > · add a write-intent bitmap to any array which support these bitmaps, or > > remove a write-intent bitmap from such an array." > > > > which suggests you can't. That might be wrong though as it sounds (to me > > anyway) like linear would be one of the easier ones to implement grow for. > > I'm not sure. The man page is out of date. With reasonably recent kernel/mdadm you can mdadm --grow /dev/mdX --add /dev/sdY To add a drive to a linear array. You then need to grow the filesystem of course. But yes: A big linear array is good for scratch space, but I wouldn't want to store data that I couldn't afford to lose. NeilBrown - 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
