On 2016-02-21 01:29, Karel Gardas wrote:
scrub is IIRC not supported by any softraid yet.
But there's "patrol"!
"bioctl -t start mysoftraid"
Rebuild by all which support redundancy.
Yey! Clarified by Marcus & looking forward to his clarification
Marcus recommendation to read man pages can just
be highlighted here. Otherwise just read the code for ultimate
reference of what is or is not done.
Yey!
On 2016-02-21 02:44, Constantine A. Murenin wrote:
On 20 February 2016 at 10:29, Karel Gardas <gard...@gmail.com> wrote:
scrub is IIRC not supported by any softraid yet. Rebuild by all which
support redundancy. Marcus recommendation to read man pages can just
be highlighted here. Otherwise just read the code for ultimate
reference of what is or is not done.
Scrub cannot possibly be supported due to the design of the softraid:
http://mdoc.su/o/softraid.4
The RAID 1 discipline does not initialize the mirror upon creation.
This is by design because all sectors that are read are written
first. There is no point in wasting a lot of time syncing random
data.
IIRC, other raid disciplines are not that much different, either.
E.g., a scrub implementation would have to be implemented on top of
the filesystem, and would have to be able to temporarily force the
reads to be done from a certain chunk only.
Long-term, it'll probably be easier to re-do the logic to actually
zero-out all the unused sectors, if scrub support is deemed important.
Which is why things like ZFS are superior due to having the awareness
of the underlying storage blocks.
Wait, I don't see the philosophical problem that you seem to be
highlighting here ("sectors are .. written first" and "on top of the
filesystem" and "forcing reads to be done from a certain chunk only"),
what am I missing/what is it that I don't understand?
Also, so you mean that "patrol" even if it's in the manual is not
supported for RAID1 nor for RAID1C nor for RAID5 or any other raid
discipline. Looking forward to see what Marcus says & test myself & read
code.
