On Feb 7, 2008, at 8:38 AM, Gerrard = Geldenhuis wrote:

I am after a bit more = documentation about the usage of the

--clustered option in = vgcreate.

At the moment I don=92t = have a spare san drive with which I can experiment. My understanding is = that you would set this flag when different hosts(nodes) connect to the = same storage area typically a san with lvm = configured.

I am after a bit more = information describing this =93clusterering=94 functionality in lvm and = how/where it is used. The man pages on lvm and commands is a bit sparse = and I am trawling through google results but not with great success at = the moment.

linux-lvm@redhat.com
In-Reply-To: References:

From: "Gerrard Geldenhuis" 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: LVM general discussion and development This is a multi-part message in MIME format. ------_=_NextPart_001_01C869A7.9A2B615E Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Thanks, the "missing snapshotting" would be a problem. I am still slightly unclear as to the goals of the clustering in LVM... =20 Regards =20 ________________________________ From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Jonathan Brassow Sent: 07 February 2008 16:21 To: LVM general discussion and development Subject: Re: [linux-lvm] Docs on clustererd option of vgcreate =20 The reason the results are likely so sparse is because the two modes of operation (single machine and cluster) are so similar. =20 Once you've setup a cluster and installed the lvm2-cluster rpm*, new volume groups that are created automatically receive the "clustered" attribute. [Toggle the cluster attribute by doing vgchange -c[ny] ] The lvm commands stay the same as if you were running them on a single machine.** =20 brassow =20 * Of course you could compile the sources or use another install method. ** Some targets (like snapshots) are not available when using LVM in a clustered mode. =20 On Feb 7, 2008, at 8:38 AM, Gerrard Geldenhuis wrote: Hi I am after a bit more documentation about the usage of the --clustered option in vgcreate. =20 At the moment I don't have a spare san drive with which I can experiment. My understanding is that you would set this flag when different hosts(nodes) connect to the same storage area typically a san with lvm configured. =20 I am after a bit more information describing this "clusterering" functionality in lvm and how/where it is used. The man pages on lvm and commands is a bit sparse and I am trawling through google results but not with great success at the moment. =20 Regards _______________________________________________ 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/ =20 ------_=_NextPart_001_01C869A7.9A2B615E Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Thanks, the “missing = snapshotting” would be a problem. I am still slightly unclear as to the goals of the = clustering in LVM…

Regards

From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] = On Behalf Of Jonathan Brassow
Sent: 07 February 2008 = 16:21
To: LVM general = discussion and development
Subject: Re: [linux-lvm] = Docs on clustererd option of vgcreate

The reason the results are likely so sparse is because the two = modes of operation (single machine and cluster) are so = similar.

Once you've setup a cluster and installed the lvm2-cluster rpm*, = new volume groups that are created automatically receive the = "clustered" attribute. [Toggle the cluster attribute by doing vgchange -c[ny] <vg>] The lvm commands stay the same as if you were running = them on a single machine.**

brassow

* Of course you could compile the sources or use another install method.

** Some targets (like snapshots) are not available when using = LVM in a clustered mode.

On Feb 7, 2008, at 8:38 AM, Gerrard Geldenhuis = wrote:

Hi<= /span>

I am after a = bit more documentation about the usage of the

--clustered = option in vgcreate.

At the moment I = don’t have a spare san drive with which I can experiment. My understanding is = that you would set this flag when different hosts(nodes) connect to the same = storage area typically a san with lvm = configured.

I am after a = bit more information describing this “clusterering” functionality in = lvm and how/where it is used. The man pages on lvm and commands is a bit sparse and I am = trawling through google results but not with great success at the = moment.

Regards

_____________= __________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.re= dhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO= /

------_=_NextPart_001_01C869A7.9A2B615E-- From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [192.168.1.101] (vpn-248-90.boston.redhat.com [10.13.248.90]) by pobox.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m17Gxn79021069 for ; Thu, 7 Feb 2008 11:59:50 -0500 Message-Id: <9BB520CB-6D8D-49A5-BF38-92BEB8875FDF@redhat.com> From: Jonathan Brassow In-Reply-To: Content-Type: multipart/alternative; boundary=Apple-Mail-95-758089343 Mime-Version: 1.0 (Apple Message framework v915) Subject: Re: [linux-lvm] Docs on clustererd option of vgcreate Date: Thu, 7 Feb 2008 10:59:48 -0600 References:

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: LVM general discussion and development --Apple-Mail-95-758089343 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed; delsp=yes Content-Transfer-Encoding: quoted-printable Clustering LVM (CLVM) provides a way to manage logical volumes in a =20 consistent way. By analogy, if you connect the same disk to two machines, put a file =20 system on it (like ext3), and mount the file system on both machines, =20= you can expect corruption. Both machines will be attempting to create/=20= modify/read metadata without the knowledge that someone else is doing =20= the same... You need a cluster aware file system in this type of =20 scenario - like GFS. The same thing is true of LVM... you don't want =20= to have two machines sharing the same volume group - extending/=20 shrinking/creating/deleting logical volumes without knowledge of the =20 other machine... it would lead to corruption of your volume group =20 layout. This is what CLVM is all about. It is especially useful when =20= coupled with a cluster-aware file system, like GFS and others. Active/=20= Active setups are where CLVM is most useful. Active/Passive setups =20 can get away with a little less = (http://sourceware.org/cluster/wiki/LVMFailover=20 ). In active/active environments, the concept of CLVM becomes even more =20 important when dealing with more complex RAID. For example, LVM =20 mirroring must be handled in a different way depending on whether a =20 logical volume is clustered or not. (This is handled transparently by =20= (C)LVM.) This is because mirroring creates its own metadata to track =20= the degree to which the component legs are in-sync... this status =20 tracking must be cluster-aware or the state will be corrupted. This =20 is the reason why there is no snapshotting in CLVM yet. The cluster-=20 coherent version has not yet been written. brassow On Feb 7, 2008, at 10:36 AM, Gerrard Geldenhuis wrote: > Thanks, the =93missing snapshotting=94 would be a problem. I am still =20= > slightly unclear as to the goals of the clustering in LVM=85 > > Regards > > From: linux-lvm-bounces@redhat.com = [mailto:linux-lvm-bounces@redhat.com=20 > ] On Behalf Of Jonathan Brassow > Sent: 07 February 2008 16:21 > To: LVM general discussion and development > Subject: Re: [linux-lvm] Docs on clustererd option of vgcreate > > The reason the results are likely so sparse is because the two modes =20= > of operation (single machine and cluster) are so similar. > > Once you've setup a cluster and installed the lvm2-cluster rpm*, new =20= > volume groups that are created automatically receive the "clustered" =20= > attribute. [Toggle the cluster attribute by doing vgchange -c[ny] =20 > ] The lvm commands stay the same as if you were running them on =20= > a single machine.** > > brassow > > * Of course you could compile the sources or use another install =20 > method. > ** Some targets (like snapshots) are not available when using LVM in =20= > a clustered mode. > > On Feb 7, 2008, at 8:38 AM, Gerrard Geldenhuis wrote: > > > Hi > I am after a bit more documentation about the usage of the > --clustered option in vgcreate. > > At the moment I don=92t have a spare san drive with which I can =20 > experiment. My understanding is that you would set this flag when =20 > different hosts(nodes) connect to the same storage area typically a =20= > san with lvm configured. > > I am after a bit more information describing this =93clusterering=94 =20= > functionality in lvm and how/where it is used. The man pages on lvm =20= > and commands is a bit sparse and I am trawling through google =20 > results but not with great success at the moment. > > Regards > _______________________________________________ > 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/ > > _______________________________________________ > 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/ --Apple-Mail-95-758089343 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Clustering LVM (CLVM) provides = a way to manage logical volumes in a consistent way.

By analogy, if you connect = the same disk to two machines, put a file system on it (like ext3), and = mount the file system on both machines, you can expect corruption. = Both machines will be attempting to create/modify/read metadata = without the knowledge that someone else is doing the same... You = need a cluster aware file system in this type of scenario - like GFS. = The same thing is true of LVM... you don't want to have two = machines sharing the same volume group - = extending/shrinking/creating/deleting logical volumes without knowledge = of the other machine... it would lead to corruption of your volume group = layout. This is what CLVM is all about. It is especially = useful when coupled with a cluster-aware file system, like GFS and = others. Active/Active setups are where CLVM is most useful. = Active/Passive setups can get away with a little less (http://sourceware= .org/cluster/wiki/LVMFailover).

In active/active = environments, the concept of CLVM becomes even more important when = dealing with more complex RAID. For example, LVM mirroring must be = handled in a different way depending on whether a logical volume is = clustered or not. (This is handled transparently by (C)LVM.) = This is because mirroring creates its own metadata to track the = degree to which the component legs are in-sync... this status tracking = must be cluster-aware or the state will be corrupted. This is the = reason why there is no snapshotting in CLVM yet. The = cluster-coherent version has not yet been written.

brassow

On Feb 7, 2008, at 10:36 AM, Gerrard Geldenhuis = wrote:

Thanks, the = =93missing snapshotting=94 would be a problem. I am still slightly = unclear as to the goals of the clustering in = LVM=85

From: linux-lvm-bounces@redhat.com<= /a> [ On Behalf Of Jonathan = Brassow
Sent: 07 February 2008 = 16:21
To: LVM general discussion and = development
Re: [linux-lvm] Docs on = clustererd option of vgcreate

The reason the results are likely so sparse = is because the two modes of operation (single machine and cluster) are = so similar.
Once you've setup a cluster and installed = the lvm2-cluster rpm*, new volume groups that are created automatically = receive the "clustered" attribute. [Toggle the cluster attribute = by doing vgchange -c[ny] <vg>] The lvm commands stay the = same as if you were running them on a single = machine.**
* Of course you could compile the sources or = use another install = method.
** Some = targets (like snapshots) are not available when using LVM in a clustered = mode.
On Feb 7, = 2008, at 8:38 AM, Gerrard Geldenhuis = wrote:
HiI am after a bit more = documentation about the usage of the--clustered option in = vgcreate.

At the moment I don=92t have a spare san drive with which I can = experiment. My understanding is that you would set this flag when = different hosts(nodes) connect to the same storage area typically a san = with lvm configured.

I am after a bit more information describing this = =93clusterering=94 functionality in lvm and how/where it is used. The = man pages on lvm and commands is a bit sparse and I am trawling through = google results but not with great success at the = moment.

Regards
linux-lvm@redhat.com
linux-lvm@redhat.com
In-Reply-To: <9BB520CB-6D8D-49A5-BF38-92BEB8875FDF@redhat.com> References: <9BB520CB-6D8D-49A5-BF38-92BEB8875FDF@redhat.com> From: "Gerrard Geldenhuis" 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: LVM general discussion and development This is a multi-part message in MIME format. ------_=_NextPart_001_01C869AE.88574BCF Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Excellent, thanks for the answer, that makes it a lot clearer. =20 So coupled with exclusion lists etc.. I could have multiple machines connect to one LUN and each have its own logical volume. Is there a concept of a "master" in the cluster or does it work in the same way as tcp with an exponential backoff when the metadata is locked by a host for changing. I am assuming that cluster aware locking would allow server-a to create a new lv but not simalteneosly allowing server-b to create a new lv too. =20 I know should be experimenting with this but will ask in the mean time while I wait for my "test lun". =20 If host A creates a lv on a shared storage will it automatically be marked as only belonging to host A or is that something you have to do by hand. I read somewhere in the man pages about tags that you need to add to achieve such things. =20 Regards =20 ________________________________ From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Jonathan Brassow Sent: 07 February 2008 17:00 To: LVM general discussion and development Subject: Re: [linux-lvm] Docs on clustered option of vgcreate =20 Clustering LVM (CLVM) provides a way to manage logical volumes in a consistent way. =20 By analogy, if you connect the same disk to two machines, put a file system on it (like ext3), and mount the file system on both machines, you can expect corruption. Both machines will be attempting to create/modify/read metadata without the knowledge that someone else is doing the same... You need a cluster aware file system in this type of scenario - like GFS. The same thing is true of LVM... you don't want to have two machines sharing the same volume group - extending/shrinking/creating/deleting logical volumes without knowledge of the other machine... it would lead to corruption of your volume group layout. This is what CLVM is all about. It is especially useful when coupled with a cluster-aware file system, like GFS and others. Active/Active setups are where CLVM is most useful. Active/Passive setups can get away with a little less (http://sourceware.org/cluster/wiki/LVMFailover). =20 In active/active environments, the concept of CLVM becomes even more important when dealing with more complex RAID. For example, LVM mirroring must be handled in a different way depending on whether a logical volume is clustered or not. (This is handled transparently by (C)LVM.) This is because mirroring creates its own metadata to track the degree to which the component legs are in-sync... this status tracking must be cluster-aware or the state will be corrupted. This is the reason why there is no snapshotting in CLVM yet. The cluster-coherent version has not yet been written. =20 brassow =20 On Feb 7, 2008, at 10:36 AM, Gerrard Geldenhuis wrote: Thanks, the "missing snapshotting" would be a problem. I am still slightly unclear as to the goals of the clustering in LVM... =20 Regards =20 ________________________________ From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Jonathan Brassow Sent: 07 February 2008 16:21 To: LVM general discussion and development Subject: Re: [linux-lvm] Docs on clustererd option of vgcreate =20 The reason the results are likely so sparse is because the two modes of operation (single machine and cluster) are so similar. =20 Once you've setup a cluster and installed the lvm2-cluster rpm*, new volume groups that are created automatically receive the "clustered" attribute. [Toggle the cluster attribute by doing vgchange -c[ny] ] The lvm commands stay the same as if you were running them on a single machine.** =20 brassow =20 * Of course you could compile the sources or use another install method. ** Some targets (like snapshots) are not available when using LVM in a clustered mode. =20 On Feb 7, 2008, at 8:38 AM, Gerrard Geldenhuis wrote: Hi I am after a bit more documentation about the usage of the --clustered option in vgcreate. =20 At the moment I don't have a spare san drive with which I can experiment. My understanding is that you would set this flag when different hosts(nodes) connect to the same storage area typically a san with lvm configured. =20 I am after a bit more information describing this "clusterering" functionality in lvm and how/where it is used. The man pages on lvm and commands is a bit sparse and I am trawling through google results but not with great success at the moment. =20 Regards _______________________________________________ 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/ =20 _______________________________________________ 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/ =20 ------_=_NextPart_001_01C869AE.88574BCF Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Excellent, thanks for the answer, = that makes it a lot clearer.

So coupled with exclusion lists = etc.. I could have multiple machines connect to one LUN and each have its own = logical volume. Is there a concept of a “master” in the cluster or = does it work in the same way as tcp with an exponential backoff when the metadata is locked = by a host for changing. I am assuming that cluster aware locking would allow server-a to create a new lv but not simalteneosly allowing server-b to = create a new lv too.

I know should be experimenting with = this but will ask in the mean time while I wait for my “test = lun”.

If host A creates a lv on a shared = storage will it automatically be marked as only belonging to host A or is that something you have to do by hand. I read somewhere in the man pages = about tags that you need to add to achieve such = things.

Regards
=

From: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] = On Behalf Of Jonathan Brassow
Sent: 07 February 2008 = 17:00
To: LVM general = discussion and development
Subject: Re: [linux-lvm] = Docs on clustered option of vgcreate

Clustering LVM (CLVM) provides a way to manage logical volumes = in a consistent way.

By analogy, if you connect the same disk to two machines, put a = file system on it (like ext3), and mount the file system on both machines, you can = expect corruption. Both machines will be attempting to create/modify/read metadata without the knowledge that someone else is doing the same... = You need a cluster aware file system in this type of scenario - like GFS. = The same thing is true of LVM... you don't want to have two machines sharing = the same volume group - extending/shrinking/creating/deleting logical = volumes without knowledge of the other machine... it would lead to corruption of = your volume group layout. This is what CLVM is all about. It is especially useful when coupled with a cluster-aware file system, like = GFS and others. Active/Active setups are where CLVM is most useful. Active/Passive setups can get away with a little less (http://sourcewar= e.org/cluster/wiki/LVMFailover).

In active/active environments, the concept of CLVM becomes even = more important when dealing with more complex RAID. For example, LVM = mirroring must be handled in a different way depending on whether a logical volume = is clustered or not. (This is handled transparently by (C)LVM.) = This is because mirroring creates its own metadata to track the degree to = which the component legs are in-sync... this status tracking must be cluster-aware or the = state will be corrupted. This is the reason why there is no snapshotting = in CLVM yet. The cluster-coherent version has not yet been = written.

brassow

On Feb 7, 2008, at 10:36 AM, Gerrard Geldenhuis = wrote:

Thanks, the “missing = snapshotting” would be a problem. I am still slightly unclear as to the goals of the = clustering in LVM…

Regards

From: linux-lvm-bounces@redhat.com= [mailto:linux-lvm-bounces@red= hat.com] On Behalf Of Jonathan Brassow
Sent: 07 February 2008 16:21
To: LVM general discussion and = development
Subject: Re: [linux-lvm] Docs on = clustererd option of vgcreate

The reason the results are likely = so sparse is because the two modes of operation (single machine and = cluster) are so similar.

Once you've setup a cluster and = installed the lvm2-cluster rpm*, new volume groups that are created automatically = receive the "clustered" attribute. [Toggle the cluster attribute = by doing vgchange -c[ny] <vg>] The lvm commands stay the same = as if you were running them on a single = machine.**

brassow

* Of course you could compile the = sources or use another install method.

** Some targets (like snapshots) = are not available when using LVM in a clustered = mode.

On Feb 7, 2008, at 8:38 AM, = Gerrard Geldenhuis wrote:

Hi<= /span>

I am after a = bit more documentation about the usage of the

--clustered = option in vgcreate.

At the moment I = don’t have a spare san drive with which I can experiment. My understanding is = that you would set this flag when different hosts(nodes) connect to the same = storage area typically a san with lvm = configured.

I am after a = bit more information describing this “clusterering” functionality in = lvm and how/where it is used. The man pages on lvm and commands is a bit sparse and I am = trawling through google results but not with great success at the = moment.

Regards

_____________= __________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.re= dhat.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.re= dhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO= /

------_=_NextPart_001_01C869AE.88574BCF-- From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from jeltz.chrissie.net (vpn-6-7.fab.redhat.com [10.33.6.7]) by pobox.fab.redhat.com (8.13.1/8.13.1) with ESMTP id m188VIJw002525 for ; Fri, 8 Feb 2008 03:31:18 -0500 Message-ID: <47AC1355.1090607@redhat.com> Date: Fri, 08 Feb 2008 08:31:17 +0000 From: Patrick Caulfeld MIME-Version: 1.0 Subject: Re: [linux-lvm] Docs on clustered option of vgcreate References: <9BB520CB-6D8D-49A5-BF38-92BEB8875FDF@redhat.com> In-Reply-To: Content-Transfer-Encoding: 8bit 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: Content-Type: text/plain; charset="utf-8" To: LVM general discussion and development Gerrard Geldenhuis wrote: > Excellent, thanks for the answer, that makes it a lot clearer. > > > > So coupled with exclusion lists etc.. I could have multiple machines > connect to one LUN and each have its own logical volume. Is there a > concept of a �master� in the cluster or does it work in the same way as > tcp with an exponential backoff when the metadata is locked by a host > for changing. I am assuming that cluster aware locking would allow > server-a to create a new lv but not simalteneosly allowing server-b to > create a new lv too. > > > > I know should be experimenting with this but will ask in the mean time > while I wait for my �test lun�. > > > > If host A creates a lv on a shared storage will it automatically be > marked as only belonging to host A or is that something you have to do > by hand. I read somewhere in the man pages about tags that you need to > add to achieve such things. > Locking in CLVM is exclusive and there's no back off. There is no reason for it, creating an LVM doesn't take very long and is done from a command-line. Host 'b' will simply wait until host 'a' has finished its job. If you need to mark LVs to be exclusive to a node you will need to use tags to define which node is allowed access