> If you "move the PE" as you suggest, you would by necessity stop using
> both the good disk and the bad disk where that PE was located, as the
> mirroring is "hidden" from LVM by the MD layer. If the mirroring was
Yes. You waste 1 PE of data this way, probably something like 4 or 16MB,
which is somewhat bad.
> in mid-stream you may not have a complete set of valid data in either
> the old or the new PE. If you CAN handle this safely, then you are 99%
> of the way to having mirroring in LVM already anyways.
. Why does LVM not support mirroring?
Mirroring or other levels of RAID on a per Logical Volume base decreases
releability because you have to take care of which Logical Volumes are
mirrored and which ones are not.
I recommend to use dedicated hardware RAID subsystems or Multiple Devices to
have the redundancy below the LVM. In this case you just don't care about
Logical Volume data redundancy and you don't run into the dangerous
situation that your data is not redundant by accident.
If you do have these kind of devices in place you can setup RAID 10/40/50 if
you like to because the LVM supports RAID0. Combining for eg. several
hardware RAID5 subsystems in volume group to set up LVM-RAID0 gives you
reliability, performance and flexibility at the same time.
Does not seem like a really technical problem.
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