[linux-lvm] Mirroring implementation

[brem belguebli <brem belguebli gmail com>]

Hi,

I have a few questions concerning LVM mirror implementation, and I couldn't find any suitable design doc

I need to setup a dual site ( a few miles between the 2 sites, around 1 ms RTD) mirror based cluster system.

-  what is the default behaviour of the mirroring, writing in parallel to both mirror legs or serialized ? what about read requests ?

- for write requests, is the ack returned to the application (thru VFS) when the 2 legs are updated or only when the first is updated ?

- Is there a way to control it ?

- what happens if the log device is lost ?

I saw a post about LVM mirror vs mdadm where it is about the location of the mirror log (https://www.redhat.com/archives/linux-lvm/2009-July/msg00012.html) someone gave the answer that when creating the LV's with --alloc anywhere it will auto locate the log on any of the PV's.

According to what I could read, the --alloc doesn't intend for that, am I right ?

Brem ,