Thank you for reply i dont mind if fstab sees partitions.  I read this "To avoid striping performance
 problems LVM can't tell that two PVs are on the same physical disk, so if
you create a striped LV then the stripes could be on different partitions  on the same disk resulting in a *decrease* in performance rather than an increase." in the tldp.org but does this apply to disks made from RAID backend ?


Warm Regards
Urgen Sherpa


On Fri, Oct 12, 2018 at 9:09 PM Heinz Mauelshagen <heinzm@redhat.com> wrote:
On 10/11/18 4:31 PM, Emmanuel Gelati wrote:
If you use sdb only for data, you don't have need to use partition on the disk.

Though that's true, keeping 1 partition per disk for each LVM PV adds additional
'visibility' by tools like fdisk/[cs]fdisk, parted etc. showing the partition type to be 'Liinux LVM'.

Using the whole disk, blkid or lsblk will provide that information still,
e.g. 'blkid --match-token TYPE=LVM2_member'.

Heinz


Il giorno gio 11 ott 2018 alle ore 16:26 David Teigland <teigland@redhat.com> ha scritto:
On Thu, Oct 11, 2018 at 08:53:07AM +0545, Sherpa Sherpa wrote:
> I have LVM(backed by hardware RAID5) with logical volume and a volume group
> named "dbstore-lv" and "dbstore-vg" which have sdb1 sdb2 sdb3 created from
> same sdb disk.

> sdb                                8:16   0  19.7T  0 disk
> ├─sdb1                             8:17   0   7.7T  0 part
> │ └─dbstore-lv (dm-1)              252:1    0   9.4T  0 lvm  /var/db/st01
> ├─sdb2                             8:18   0   1.7T  0 part
> │ └─dbstore-lv (dm-1)              252:1    0   9.4T  0 lvm  /var/db/st01
> └─sdb3                             8:19   0  10.3T  0 part
>   └─archive--archivedbstore--lv (dm-0)     252:0    0  10.3T  0 lvm

> I am assuming this is due to disk seek problem as the same disk partitions
> are used for same LVM or may be its due to saturation of the disks

You shouldn't add different partitions as different PVs.  If it's too late
to fix, it might help to create new LV that uses only one of the
partitions, e.g. lvcreate -n lv -L size vg /dev/sdb2, and then copy your
current LV to the new one.

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