[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Gang He]

Hello Guys,

Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules. 

Any comments/suggestions? 


Thanks a lot
Gang

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Changwei Ge]

Hello Gang,

On 4/10/20 4:36 PM, Gang He wrote:
> Hello Guys,
> 
> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.

Some quick questions:

1.Will the 'nocluster' ocfs2 volume be read-only?
2.How to achieve filesystem consistency if the whole cluster or some 
members of it crashed before this 'nocluster' mount.
3.Is there any mechanism guard protecting no other node do mount after 
this 'nocluster' mount.
4.Why do we have potential work for mounted.ocfs2?
5.I feel debugfs.ocfs2 can dump specified file or entire volume, is that 
satisfied for you?

Thanks,
Changwei


> 
> Any comments/suggestions?
> 
> 
> Thanks a lot
> Gang
> 
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Gang He]

Hello Changwei,

See my comments inline.

________________________________________
From: Changwei Ge <chge@linux.alibaba.com>
Sent: Friday, April 10, 2020 5:08 PM
To: Gang He; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

Hello Gang,

On 4/10/20 4:36 PM, Gang He wrote:
> Hello Guys,
>
> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.

Some quick questions:

1.Will the 'nocluster' ocfs2 volume be read-only?
The user can read or write this mount (like local mount), but the user needs to make sure only one node can mount 
the volume like this way.

2.How to achieve filesystem consistency if the whole cluster or some
members of it crashed before this 'nocluster' mount.
The mount process will do the recovery for each node's journal, but the mount process will not do DLM related things. 

3.Is there any mechanism guard protecting no other node do mount after
this 'nocluster' mount.
Not, we can give a warning during the mount period.
If the customer need to understand this risk. 

4.Why do we have potential work for mounted.ocfs2?
Maybe we need to add some code, let mounted.ocfs2 aware this mount option.
In short, I am not 100% sure if there is something to do.

5.I feel debugfs.ocfs2 can dump specified file or entire volume, is that
satisfied for you?
For the developer, we can do like that way.
But for the customer, it is too hard.
and that, the customer wants to access lots of files for one time.

Thanks
Gang

Thanks,
Changwei


>
> Any comments/suggestions?
>
>
> Thanks a lot
> Gang
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Changwei Ge]

At least for class o2cb stack, I suppose if cluster was once set up 
successfully, it won't be hard to mount from a single node.
Or do you lose your cluster configuration somehow?

On 4/10/20 5:28 PM, Gang He wrote:
> Hello Changwei,
> 
> See my comments inline.
> 
> ________________________________________
> From: Changwei Ge <chge@linux.alibaba.com>
> Sent: Friday, April 10, 2020 5:08 PM
> To: Gang He; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers
> 
> Hello Gang,
> 
> On 4/10/20 4:36 PM, Gang He wrote:
>> Hello Guys,
>>
>> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
>> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
>> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
>> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
>> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
>> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
>> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.
> 
> Some quick questions:
> 
> 1.Will the 'nocluster' ocfs2 volume be read-only?
> The user can read or write this mount (like local mount), but the user needs to make sure only one node can mount
> the volume like this way.
> 
> 2.How to achieve filesystem consistency if the whole cluster or some
> members of it crashed before this 'nocluster' mount.
> The mount process will do the recovery for each node's journal, but the mount process will not do DLM related things.
> 
> 3.Is there any mechanism guard protecting no other node do mount after
> this 'nocluster' mount.
> Not, we can give a warning during the mount period.
> If the customer need to understand this risk.
> 
> 4.Why do we have potential work for mounted.ocfs2?
> Maybe we need to add some code, let mounted.ocfs2 aware this mount option.
> In short, I am not 100% sure if there is something to do.
> 
> 5.I feel debugfs.ocfs2 can dump specified file or entire volume, is that
> satisfied for you?
> For the developer, we can do like that way.
> But for the customer, it is too hard.
> and that, the customer wants to access lots of files for one time.
> 
> Thanks
> Gang
> 
> Thanks,
> Changwei
> 
> 
>>
>> Any comments/suggestions?
>>
>>
>> Thanks a lot
>> Gang
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>>

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Joseph Qi]

Just be curious about this user scenario.
What is "without DLM/cluster environment"?

Thanks,
Joseph

On 2020/4/10 16:36, Gang He wrote:
> Hello Guys,
> 
> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules. 
> 
> Any comments/suggestions? 
> 
> 
> Thanks a lot
> Gang
> 
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Gang He]

Hello Jeseph,

________________________________________
From: Joseph Qi <jiangqi903@gmail.com>
Sent: Friday, April 10, 2020 6:00 PM
To: Gang He; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

Just be curious about this user scenario.
What is "without DLM/cluster environment"?

The user can mount the existent ocfs2 cluster volume directly, does not depend on if DLM/cluster services are available.
When this option is added, the mount process  will not do dlm related things, like local mount.
This way will help the user access the files in the volume quickly for avoiding setup/online the cluster environment.

Thanks
Gang
 
Thanks,
Joseph

On 2020/4/10 16:36, Gang He wrote:
> Hello Guys,
>
> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.
>
> Any comments/suggestions?
>
>
> Thanks a lot
> Gang
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Joseph Qi]

On 2020/4/10 18:16, Gang He wrote:
> Hello Jeseph,
> 
> ________________________________________
> From: Joseph Qi <jiangqi903@gmail.com>
> Sent: Friday, April 10, 2020 6:00 PM
> To: Gang He; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers
> 
> Just be curious about this user scenario.
> What is "without DLM/cluster environment"?
> 
> The user can mount the existent ocfs2 cluster volume directly, does not depend on if DLM/cluster services are available.
> When this option is added, the mount process  will not do dlm related things, like local mount.
> This way will help the user access the files in the volume quickly for avoiding setup/online the cluster environment.
> 
But it is cheap to online cluster, even there is only one node, right?


> 
> On 2020/4/10 16:36, Gang He wrote:
>> Hello Guys,
>>
>> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
>> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
>> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
>> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
>> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
>> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
>> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.
>>
>> Any comments/suggestions?
>>
>>
>> Thanks a lot
>> Gang
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>>
> 
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Gang He]

Hi Joseph,

________________________________________
From: Joseph Qi <joseph.qi@linux.alibaba.com>
Sent: Friday, April 10, 2020 8:49 PM
To: Gang He; Joseph Qi; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers



On 2020/4/10 18:16, Gang He wrote:
> Hello Jeseph,
>
> ________________________________________
> From: Joseph Qi <jiangqi903@gmail.com>
> Sent: Friday, April 10, 2020 6:00 PM
> To: Gang He; ocfs2-devel at oss.oracle.com; ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers
>
> Just be curious about this user scenario.
> What is "without DLM/cluster environment"?
>
> The user can mount the existent ocfs2 cluster volume directly, does not depend on if DLM/cluster services are available.
> When this option is added, the mount process  will not do dlm related things, like local mount.
> This way will help the user access the files in the volume quickly for avoiding setup/online the cluster environment.
>
But it is cheap to online cluster, even there is only one node, right?

You know, ocfs2 uses two cluster stack (o2cb and pcmk).
If the user select pcmk stack to setup a ocfs2 cluster file system, 
they need to setup a pacemaker cluster according to the guide,
then they need to add some configurations(e.g. stonith/dlm resource) via pacemaker shell interface.
the whole setup process is a little heavy for the user. 

Thanks
Gang
 



>
> On 2020/4/10 16:36, Gang He wrote:
>> Hello Guys,
>>
>> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
>> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
>> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
>> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
>> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
>> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
>> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.
>>
>> Any comments/suggestions?
>>
>>
>> Thanks a lot
>> Gang
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>>
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>

[Ocfs2-devel] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[herbert.van.den.bergh at oracle.com]

Hello Gang,

The option to mount without a clusterstack is: heartbeat=none

Give that a try and let us know if that doesn't work.

Thanks,
Herbert.

On 4/10/20 1:36 AM, Gang He wrote:
> Hello Guys,
>
> Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with a shared volume.
> but the customers complained they could not mount existent ocfs2 volume in the local mode without DLM/cluster envirnment in backup/restore scenario.
> in this case, the customers want to mount this ocfs2 volume from one node without cluster aware way, sometimes the customers have stoped(uninstalled) the whole cluster before the backup/restore, they just want to access the data from the ocfs2 volume.
> Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local" option is a little confused for the users, since we have a local mount volume concept).
> If the users use "nocluster" option to mount a ocfs2 volume, the whole mount will not depend on the DLM/cluster related services. they
> will mount the existent ocfs2 volume directly (like local mount) for avoiding setup the cluster stacks.
> The code change is small with my preliminary investigation, the main affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in the ocfs2 kernel modules.
>
> Any comments/suggestions?
>
>
> Thanks a lot
> Gang
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel

[Ocfs2-devel] [Ocfs2-users] mount existent ocfs2 volume in the local mode without the extra DLM, pacemaker/corosync layers

[Gang He]

Hello Herbert,

As you know, ocfs2 has two cluster stacks,
One is o2cb, the other one is pcmk.
For o2cb stack, ocfs2 will use heartbeat argument.
When the volume is detected as a local-mount volume, mount.ocfs2 will pass "heartbeat=none" argument to mount system call.
For pcmk stack, ocfs2 does not use heartbeat mount option, that means heartbeat option is always none.


Thanks
Gang 

> -----Original Message-----
> From: ocfs2-users-bounces at oss.oracle.com
> [mailto:ocfs2-users-bounces at oss.oracle.com] On Behalf Of
> herbert.van.den.bergh at oracle.com
> Sent: 2020?4?11? 1:10
> To: Gang He <GHe@suse.com>; ocfs2-devel at oss.oracle.com;
> ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-users] [Ocfs2-devel] mount existent ocfs2 volume in the
> local mode without the extra DLM, pacemaker/corosync layers
> 
> Hello Gang,
> 
> The option to mount without a clusterstack is: heartbeat=none
> 
> Give that a try and let us know if that doesn't work.
> 
> Thanks,
> Herbert.
> 
> On 4/10/20 1:36 AM, Gang He wrote:
> > Hello Guys,
> >
> > Usually, we create a ocfs2 cluster on the top DLM(pacemaker/corosync) with
> a shared volume.
> > but the customers complained they could not mount existent ocfs2 volume
> in the local mode without DLM/cluster envirnment in backup/restore scenario.
> > in this case, the customers want to mount this ocfs2 volume from one node
> without cluster aware way, sometimes the customers have stoped(uninstalled)
> the whole cluster before the backup/restore, they just want to access the data
> from the ocfs2 volume.
> > Then, I'd like to add a mount option, e.g. "nocluster" (I feel using "local"
> option is a little confused for the users, since we have a local mount volume
> concept).
> > If the users use "nocluster" option to mount a ocfs2 volume, the whole
> > mount will not depend on the DLM/cluster related services. they will mount
> the existent ocfs2 volume directly (like local mount) for avoiding setup the
> cluster stacks.
> > The code change is small with my preliminary investigation, the main
> affected places are mount.ocfs2/mounted.ocfs2 tools and mount process in
> the ocfs2 kernel modules.
> >
> > Any comments/suggestions?
> >
> >
> > Thanks a lot
> > Gang
> >
> > _______________________________________________
> > Ocfs2-devel mailing list
> > Ocfs2-devel at oss.oracle.com
> > https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 
> _______________________________________________
> Ocfs2-users mailing list
> Ocfs2-users at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-users