On Tue, 16 Sep 2014 15:03:41 -0400 Ken Heard <kensli...@teksavvy.com> wrote:
> My first question is: although both drives are the same size, can I get > away with having one drive a Seagate 3.0 and the other Samsung 2.0? Indeed, this is a very recommended configuration, as HDz of the same brand (and much worse: same brans/model/series) have many more chances to break down together. > It occurred to me that if I made the change described in the first > paragraph -- but without somehow making the data already on it > unreadable -- there would be a different data set on each drive; so > that the RAID1 software would not necessarily know which drive should > be the data source to copy to the other drive. It also occurred to me > that the software could combine the data on each drive, so that both > drives would have both data sets. That doesn't work like that; first, you have a special block that tells who's who, 2nd, as you'll add the samsung to the array, the system considers that last arrived = new = slave, not master (of data). > I consequently assume that the data on the replacement drive must > somehow be made unreadable. Is that assumption correct? If so, do the > data have to be "shredded", or is it sufficient simply either to > "delete" them or simply reformat the drive? That doesn't matter as the software RAID will detect data presence (IF superblocks are at the same place, read: same partition(s) as now), thus, it MAY complain about this data presence and you MIGHT be obliged to force data overwrite on it. > Finally, once I have a "clean" new drive installed, will the RAID1 > copying process partition the new drive the same way as the other drive > and copy the files without further human intervention? Keep in mind that it can fail for the following reason: HDz aren't exactly the same size (except when same brand, model, series); so if your samsung (partition or full HD, YMMV about raw RAID or not) is even 1 sector less than the ST one, RAID will refuse to reconstruct. More isn't a problem as RAID will only use what it needs. If you reach this point, I strongly suggest making a bit copy (dd) of the working ST HD, then try to shrink it (if the FS allows it, eg: XFS doesn't), then if it succeed, re-add the samsung. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20140916212213.69c6c6c6@msi.defcon1