Re: [linux-lvm] lvcreate --thin gives "unknown segment type" error

[Kumar amit mehta <gmate.amit@gmail.com>]

On Mon, Jul 22, 2013 at 06:57:42AM -0400, Kumar amit mehta wrote:
> On Mon, Jul 22, 2013 at 02:15:36PM +0200, Zdenek Kabelac wrote:
> > configure --with-thin=internal
> > 
> > (and you will likely miss  '--enable-udev_sync'
> Thank you, it worked!
> 
> However, It seems that "discards" behavior for thin pool is not
> supported on RHEL 6.4. Please confirm. 
> # ./configure --with-thin=internal --enable-debug
> 
> # make; make install
> 
> # lvcreate --discards passdown -L 1G -T thinvg1/thinlv1
>   Logical volume "thinlv1" created
> 
> # lvs -o +devices|grep -i thinlv1
>   thinlv1       thinvg1       twi-a-tz-   1.00g               0.00
> thinlv1_tdata(0)
> 
> # dmesg
> device-mapper: thin: Data device (dm-3) discard unsupported: Disabling
> discard passdown.
> 
> <snip>
>         if (reason) {
>                 DMWARN("Data device (%s) %s: Disabling discard
> passdown.", bdevname(data_bdev, buf), reason);
>                 pt->adjusted_pf.discard_passdown = false;
>         } 
> <snip>
> 
> Seems that we'll reach here if QUEUE_FLAG_DISCARD flag in the request
> queue is not set.

More information of my setup:

<snip from /etc/lvm/lvm.conf>
issue_discards = 1
<snip from /etc/lvm/lvm.conf>

I'm invoking these commands on a VM. I do not know, from where these
storage were mapped to my VM(were done my some storage admin). However
when i invoke sg_inq (from sg3_utils) to get some information, that fails
too :(

<snip>
# sg_inq /dev/vde
Both SCSI INQUIRY and fetching ATA information failed on /dev/vde
<snip>

!!amit