Comment #15 on issue 455749 by
etco...@gmail.com: "your profile could not
I'm just one of the users this is happening to. But I also happen to know
a lot about SSDs.
First, my disk was nowhere near full (of user data) when this happened --
and it's happened to me multiple times. (Each time, I have to PowerWash,
which conveniently empties the disk...)
My suspicion is that the problem occurs in writing the profile data
(perhaps the last shutdown). When the problem occurs, it is sticky, so it
is not likely due to timeout on reads.
From what I see in the reports above, I'd be suspicious that the SQL
database is doing something different from other types of accesses. For
example, non-4KB-aligned (from the SSDs idea of alignment) operations. If
there was some generic SSD problem, then wouldn't this happen more
frequently and affect other saved data, including potentially the Chrome OS
system when it is updated. Yet I've seen no evidence of other corruption
(no cached pages that fail to load, no mysterious crashes, ...). What's
the size of the profile data vs. all this other data, and what are the odds
that the profile data alone would fail multiple times with no failures
(observed) elsewhere?
I'm not sure what the ("Failing CreateMapBlock") errors reported above are,
but it would be good to understand what mode the SSD is operating in (is it
a SATA SSD? is it using command queuing?), and exactly what if any errors
the SSD is reporting and in what circumstances. That would seem to be key
to getting to the bottom of this.
For example, one suspicious would be that the SSD is slow (due to a
combination of garbage collection and non-aligned operations) when the
system is shut down, and something is not waiting for the SSD to be truly
done with all outstanding ops when power is removed....