Mikael Abrahamsson wrote:

On Thu, 12 Nov 2009, Bill Davidsen wrote:

quoted

I like 1.2, I feel it's least likely to suffer collateral damage, and 
the problems it causes seem to result in the type of behavior you 
mention aboue, the system says "Can't, won't, you don't know what 
you're doing."

What about adding a new v1.3 superblock which basically has 4 
superblocks, an old 1.x superblock residing at <end>-<v1.0 superblock 
size> (new location), and then pointers to this block residing where 
1.0, 1.1 and 1.2 superblocks would normally be? Wouldn't that solve 
"everybodys" problem by making it easier to find the superblock 
regardless of what might have happened (drive size changed because of 
3ware, someone installed mbr on the drive etc).

Is it because it's early in the morning and I haven't had coffee, or is 
that starting to sound like raid-1 with superblocks? I just have to feel 
that it would increase the chances of something "looking like" a 
superblock, but wasn't. Then we could have reshape of superblocks in 
--grow, all in all that idea feels as though it's inviting them to be 
different. Imagine an array with partitions, each of which is in an 
array (like raid-1+0) with superblocks everywhere.

I'm sure other people will have thoughts on this, but given the problems 
we have with mismatch_cnt in mirrors, I wouldn't trust them to stay the 
same. And all would have to be updated, of course, makes for much disk 
writing.

-- 
Bill Davidsen [off-list ref]
  "We can't solve today's problems by using the same thinking we
   used in creating them." - Einstein