[linux-lvm] how to set higher then 128 nr_requests on LV's

[Zdenek Kabelac]

Dne 14.5.2018 v 02:47 Pankaj Agarwal napsal(a):
> Hi,
> 
> 
> How do i set the nr_request value for LV's as it's not writable like other 
> drives on a linux system.
> 
> LV's are set as dm-0 and dm-1 on my system.
> 
>   #cat /sys/block/dm-0/queue/nr_requests
> 128
> # echo 256 > /sys/block/dm-0/queue/nr_requests
> -bash: echo: write error: Invalid argument
> #


Hi

Lvm2 is 'logical volume manager'  - so it really is just managing your metadata.

So you basically ask how you change this value for 'DM' device (managed by lvm2).

And IMHO my answer would be - you can't change this setting for DM device as 
you use whatever comes from the layer bellow DM - so i.e. if you use  PV as 
/dev/sdb  - you need to set this setting for your /dev/sdb  device.

Regards

Zdenek