[linux-lvm] very slow sequential writes on lvm raid1 (bitmap?)

[Alexander 'Leo' Bergolth]

On 11/08/2016 10:26 AM, Zdenek Kabelac wrote:
> Dne 7.11.2016 v 16:58 Alexander 'Leo' Bergolth napsal(a):
>> On 11/07/2016 11:22 AM, Zdenek Kabelac wrote:
>> Is there a way to change the regionsize for an existing LV?
>
> I'm afraid there is not yet support for runtime 'regionsize' change
> other then rebuilding array.

Unfortunately even rebuilding (converting to linear and back to raid1)
doesn't work.

lvconvert seems to ignore the --regionsize option and use defaults:

lvconvert -m 0 /dev/vg_sys/lv_test
lvconvert --type raid1 -m 1 --regionsize 128M /dev/vg_sys/lv_test

[10881847.012504] mdX: bitmap initialized from disk: read 1 pages, set
4096 of 4096 bits

... which translates to a regionsize of 512k for a 2G volume.

:-(

Cheers,
--leo
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