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

[Zdenek Kabelac]

Dne 8.11.2016 v 16:15 Alexander 'Leo' Bergolth napsal(a):
> 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.



Hi

After doing some simulations here -

What is the actually USB device type used here?

Aren't you trying to deploy some attached SD-Card/USB-Flash  as your secondary 
leg?

Regards

Zdenek