On 9/1/20 6:37 AM, David Teigland wrote:
On Sun, Aug 30, 2020 at 11:49:38PM +0800, heming.z...@suse.com wrote:
in my opinion, the 'not available'
We already use the word available/unavailable in other ways, so let's use
"broken" for the moment, maybe we can find a better word.
'lvs -o broken' would report 0|1. Choosing an attr letter to represent
that is not as important and can be decided on later.
'broken' is acceptable and good word.
I'm only afraid end user don't know there is a new string item for lvs.
like me, I just know the lv_health_status string item from Zdenek's mail.
(sorry for my stupid)
means the LV can't correctly do r/w io.
for raid, if the missing or breaking underlying devs number beyond raid level
limit. the
'not available' shoud be display.
for linear, any one of underlying dev is missing, upper layer module like fs
may don't work
(e.g. missing first disk, fs will missing w/r first disk's super-block
metadata). the
'not available' should be display.
That definition of "broken" could be a specific enough, if we can report
it accurately enough. Do we need to say "io will succeed on the entire LV
(as far as lvm knows)"? It would be nice to know in which cases lvm can
report it accurately, and in which cases lvm doesn't know enough to report
it accurately. If it's not correct in many cases, then we should consider
a different definition (maybe raid-specific.)
I prefer lvm report status from the entire LV side.
lvm provides virtual blocks to upper layer softwares, most of softwares use
whole virtual disk.
there must have some scenarios which lvm doesn't know LV status accurately.
there is example about lvm doesn't know LV status. (it's very like other
modules bug not lvm problem)
if removing one of raidX sub-disks then do re-insert, the lvs will report LV
work normally.
But from my env, I saw the re-inserted disk major:minor was changed. The
device-mapper table still
keep old major:minor mapping, LV r/w io will send no-exist disk and trigger r/w
error.
So if we want to report LV status accurately, the code should do a lot of
works, like verifying DM table
mapping, verifying underlying devs, verifying raid level limit, ...
for other type LV, I don't have too much experience to answer this question.
Any LV not using raid (or mirror) will be equivalant to linear, and be
broken if a single disk is missing or broken.
Dave
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