From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 References: <20181011142550.GA15437@redhat.com> <581cfd57-aca0-70f5-b715-f05357e4bbad@redhat.com> In-Reply-To: <581cfd57-aca0-70f5-b715-f05357e4bbad@redhat.com> From: Sherpa Sherpa Date: Fri, 12 Oct 2018 21:31:35 +0545 Message-ID: Content-Type: multipart/alternative; boundary="000000000000374fb405780a00c8" Subject: Re: [linux-lvm] what is the IOPS behavior when partitions of single disk(raid5 backend) are used in an LVM? Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: To: linux-lvm@redhat.com, heinzm@redhat.com --000000000000374fb405780a00c8 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 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=3DLVM2_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 >> > =E2=94=9C=E2=94=80sdb1 8:17 0 7.7T 0 = part >> > =E2=94=82 =E2=94=94=E2=94=80dbstore-lv (dm-1) 252:1 0 = 9.4T 0 lvm >> /var/db/st01 >> > =E2=94=9C=E2=94=80sdb2 8:18 0 1.7T 0 = part >> > =E2=94=82 =E2=94=94=E2=94=80dbstore-lv (dm-1) 252:1 0 = 9.4T 0 lvm >> /var/db/st01 >> > =E2=94=94=E2=94=80sdb3 8:19 0 10.3T 0 = part >> > =E2=94=94=E2=94=80archive--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 la= te >> 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. >> >> _______________________________________________ >> linux-lvm mailing list >> linux-lvm@redhat.com >> https://www.redhat.com/mailman/listinfo/linux-lvm >> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > > > -- > .~. > /V\ > // \\ > /( )\ > ^`~'^ > > _______________________________________________ > linux-lvm mailing listlinux-lvm@redhat.comhttps://www.redhat.com/mailman/= listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ --000000000000374fb405780a00c8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Thank you for reply i dont mind if fstab sees partitions.= =C2=A0=C2=A0I read th= is "To avoid striping performance
=C2=A0problems 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=C2=A0=C2=A0on t= he same disk resulting in a *decrease* in performance rather than an=C2=A0increase." in the= tldp.org but does this apply to disks made= from RAID backend ?


Warm Regards
Urgen Sh= erpa


On Fri, Oct 12, 2018 at 9:09 PM Heinz Mauelshagen <heinzm@redhat.com> = wrote:
=20 =20 =20
On 10/11/18 4:31 PM, Emmanuel Gelati wrote:
=20
If you use sdb only for data, you don't have nee= d 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. showi= ng 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=3DLVM2_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" whic= h have sdb1 sdb2 sdb3 created from
> same sdb disk.

> sdb=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 8:16=C2=A0 =C2=A00= =C2=A0 19.7T=C2=A0 0 disk
> =E2=94=9C=E2=94=80sdb1=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A08:17=C2= =A0 =C2=A00=C2=A0 =C2=A07.7T=C2=A0 0 part
> =E2=94=82 =E2=94=94=E2=94=80dbstore-lv (dm-1)=C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 252:1=C2=A0 =C2=A0 0=C2=A0 =C2=A09.4T=C2= =A0 0 lvm=C2=A0 /var/db/st01
> =E2=94=9C=E2=94=80sdb2=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A08:18=C2= =A0 =C2=A00=C2=A0 =C2=A01.7T=C2=A0 0 part
> =E2=94=82 =E2=94=94=E2=94=80dbstore-lv (dm-1)=C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 252:1=C2=A0 =C2=A0 0=C2=A0 =C2=A09.4T=C2= =A0 0 lvm=C2=A0 /var/db/st01
> =E2=94=94=E2=94=80sdb3=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A08:19=C2= =A0 =C2=A00=C2=A0 10.3T=C2=A0 0 part
>=C2=A0 =C2=A0=E2=94=94=E2=94=80archive--archivedbstore--lv (d= m-0)=C2=A0 =C2=A0 =C2=A0252:0=C2=A0 =C2=A0 0=C2=A0 10.3T=C2=A0 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.=C2= =A0 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.

_______________________________________________
linux-lvm mailing list
linux-l= vm@redhat.com
https://www.redhat.com/mailman/listinfo/l= inux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/


--
=C2=A0 .~.
=C2=A0 /V\
=C2=A0// =C2=A0\\
/( =C2=A0 )\
^`~'^

_______________________________________________
linux-lvm mailing list
linux-lvm@red=
hat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

  


_______________________________________________

linux-lvm mailing list

linux-lvm@redhat.=
com

https://www.redhat.com/mailman/listinfo/linux-lvm

read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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