On Jan 16, 2010, at 11:46 AM, Les Mikesell <lesmikesell at gmail.com> wrote: > Adrian Sevcenco wrote: >> Ross Walker wrote: >>> On Jan 16, 2010, at 10:27 AM, Adrian Sevcenco >>> <Adrian.Sevcenco at cern.ch> wrote: >>> >>>> Hi! >>>> I have 2 identical hdd (1002FBYS) with the same firmware, etc .. >>>> really >>>> identical! when i try to add the second hdd to this raid1 array i >>>> have >>>> the message that /dev/sdb is not large enough to join array!! >>>> on the first hdd i have 100 mb unpartitioned at the end of disk >>>> (as i >>>> understood that mdadm put there some info...) >>>> Anyone, any idea what can be wrong? i already done this procees >>>> several >>>> times and this is first time i encounter this and i have no idea >>>> what >>>> can be the problem .. >>> Make sure the partitions are exactly the same, you can use sfdisk to >>> copy the table from a to b. >> well, i was doing raid over device (md_dX) but i found out the >> problem : >> even if there are "identical" devices, they have different number of >> blocks (hdparm output). how is this possible? >> is there a way to restrict the number of blocks that a hdd have? >> alternative would be just to clone the first hdd on the "smaller" one >> and then add the big one to and raid1 array ... >> >> Did someone seen this situation? > > I've seen a case where single drive volumes initialized in different > (but > identical) IBM 3550's with adaptec raid controlers would end up with > slightly > different sizes and wouldn't match up if moved. I think this was a > bios or > firmware difference but I'm not exactly sure. I was trying to clone > disks and > just started over with the smaller source so it would work everywhere. Les might be on to something here I remember some BIOS store a per- device LBA setting which might cause to sizes to differ. This brings up a good reason to use partitions as it will allow you to coerce the size down a little 128-256MB so if you need to replace a drive with a different manufacturer's drive in the future you will have a better chance in making it fit. -Ross