Re: [linux-lvm] pvmove --abort

2020-01-28 Thread Matthias Leopold




Am 27.01.20 um 17:22 schrieb Matthias Leopold:

Hi,

I consciously used "pvmove --abort" for the first time now and I'm 
astonished it doesn't behave like described in the man page. No matter 
if I've used "--atomic" for the original command, when I interrupt the 
process with "pvmove --abort" lvm always completely rolls back my copy 
operation. I would expect that if I don't use "--atomic" then "--abort" 
will result in "segments that have been moved will remain on the 
destination PV, while unmoved segments will remain on the source PV" 
(from man page). Am I missing something?


I'm using CentOS 7.7.

thx for answers. apparently I misunderstood the "--atomic" and "--abort" 
options.


matthias


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Re: [linux-lvm] pvmove --abort

2020-01-27 Thread Zdenek Kabelac

Dne 27. 01. 20 v 17:38 Stuart D Gathman napsal(a):

On Mon, 27 Jan 2020, Matthias Leopold wrote:

I consciously used "pvmove --abort" for the first time now and I'm 
astonished it doesn't behave like described in the man page. No matter if 
I've used "--atomic" for the original command, when I interrupt the process 
with "pvmove --abort" lvm always completely rolls back my copy operation. I 
would expect that if I don't use "--atomic" then "--abort" will result in 
"segments that have been moved will remain on the destination PV, while 
unmoved segments will remain on the source PV" (from man page). Am I missing 
something?


I'm not an LVM guru, but I think I got this one!  pvmove effectively
creates a mirror on the destination, and begins syncing the mirror.
Any writes to the LV go to *both* the source and destination.
When you abort, it simply discards the partially synced mirror.
When the sync is complete, it discards the source leg of the mirror
instead.




Yep - lvm2 does not look at mirrored percentage to estimate and recalculate
'probably' moved portion of some LVs to other 'devices'.

Either full mirror is 'completed' or the whole 'mirroring' is simply discarded.

Option --atomic is then about having finished ALL mirrors - aka whole thing is 
either finished or canceled.


Unfortunately resolving some sort of 'partial' abort (aka keep 'mirrored' 
data) is pretty complex task and such operation is so infrequently used that 
I'm not expecting implantation any time soon if ever...



Zdenek

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Re: [linux-lvm] pvmove --abort

2020-01-27 Thread Stuart D Gathman

On Mon, 27 Jan 2020, Matthias Leopold wrote:

I consciously used "pvmove --abort" for the first time now and I'm astonished 
it doesn't behave like described in the man page. No matter if I've used 
"--atomic" for the original command, when I interrupt the process with 
"pvmove --abort" lvm always completely rolls back my copy operation. I would 
expect that if I don't use "--atomic" then "--abort" will result in "segments 
that have been moved will remain on the destination PV, while unmoved 
segments will remain on the source PV" (from man page). Am I missing 
something?


I'm not an LVM guru, but I think I got this one!  pvmove effectively
creates a mirror on the destination, and begins syncing the mirror.
Any writes to the LV go to *both* the source and destination.
When you abort, it simply discards the partially synced mirror.
When the sync is complete, it discards the source leg of the mirror
instead.


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[linux-lvm] pvmove --abort

2020-01-27 Thread Matthias Leopold

Hi,

I consciously used "pvmove --abort" for the first time now and I'm 
astonished it doesn't behave like described in the man page. No matter 
if I've used "--atomic" for the original command, when I interrupt the 
process with "pvmove --abort" lvm always completely rolls back my copy 
operation. I would expect that if I don't use "--atomic" then "--abort" 
will result in "segments that have been moved will remain on the 
destination PV, while unmoved segments will remain on the source PV" 
(from man page). Am I missing something?


I'm using CentOS 7.7.

thx
matthias


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