>
> I searched the mailing list archive. I am not sure whether Vinum has
> solved the problem of atomic writes in a stripe to both the data fragment
> and parity fragment (RAID 5). In the case of a crash, you have no idea of
> where the writes have finished (even worse, a fragment may contain
> several sectors).
This problem can't be solved with software-only RAID, and no (sensible)
software RAID implementation attempts to deal with it. Software RAID
reliability is predicated on the correct functioning of the system; it's
there to provide fault tolerance for the high-failure-rate hardware (eg.
disks).
> If this problem is not easily solved in software, does it mean that only
> hardware RAID can guarantee availability of data and software RAID can
> only be used to increase performance? How about the Linux software RAID
> support?
Typically you work around this by using a hardware RAID adapter with
battery-backed memory; you need nonvolatile storage to achieve the
results you're looking for.
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