[linux-lvm] what is the IOPS behavior when partitions of single disk(raid5 backend) are used in an LVM?

[Heinz Mauelshagen]

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 at redhat.com <mailto:teigland at 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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>
>
>
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