Re: raid10 redundancy

Peter Grandi [off-list ref]

This looks like a "homework" question... There are a lot of
pages on the WWW that explain that in summary and detail, and
the shortest is: RAID10 only loses data if all devices that
compose one of mirror set become impaired at the same block
addresses.

 yes it is like a "homework" question. but there is not many
information for linux raid10.
like someone who test raid10,f2  and said it is fast, but others said
raid1 is faster with fio under multiple sessions.
so I always just use raid1 when I have only two disks.
this time I have a need that the two disk linux raid1 may need to grow
to 3 or 4 disks in the future. and I found:

1. raid1 can not reshape to raid 10
2. raid10,f2 can not reshape
3. someone report at the list that raid 10,o2 reshape is broken.

the above seems leave me the only option is raid10,n2