[linux-lvm] Why is my LVM Mirror performance so bad?

[Linda A. Walsh]

Errol Neal wrote:
> Is this just the life of a LVM mirror and the performance here is about as good as it gets?
> ----
>   
It's a bit confusing from what you have above, but *usually*, if you
want performance, you set up 1 duplicate device (disk) to duplicate another
of the same type.  That way when the controller is writing to 1, it will 
be able to
write to the other in the same location and expect *similar* speeds 
(speeds will
vary more on desktop drives vs. enterprise, so overall RAID performance 
is lost).

 From what it looks like you have multiple segments mirroring other 
(parallel?? not sure)
segments... but as data is being written to one segment, it also may not 
have finished
writing a  parallel copy to another segment.

Don't setup multiple segments mirroring each other on 2 devices... have 
1 be the mirror
of the other and both be of similar type if you want near device speed.

i.e. you don't want 4 mirrors, but want to make all of sdb mirror all of 
sdc.