[linux-lvm] LVM feature parity with MD

[linux-lvm] LVM feature parity with MD

[Jason Czerak]

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I found the presentation linked below regarding LVM's new features and I'm wondering if anyone shed any light on when these may become stable? Specifically the RAID0 reshaping.

https://guug.de/veranstaltungen/ffg2016/slides/Heinz%20Mauelshagen%20-%20Neueste%20Entwicklungen%20in%20LVM%20RAID.pdf

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Jason Czerak


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Re: [linux-lvm] LVM feature parity with MD

[Brassow Jonathan]

We are working on reviewing the patches ATM.  The short answer to “when” is when you start seeing the upstream commits start flowing into the various trees.  There are kernel patches required, followed by a number of userspace enablement patches.  We hope it is measured in weeks, not months.

Thanks,
 brassow

> On Apr 26, 2016, at 1:25 PM, Jason Czerak <jczerak@sgi.com> wrote:
> 
> I found the presentation linked below regarding LVM’s new features and I’m wondering if anyone shed any light on when these may become stable? Specifically the RAID0 reshaping.
>  
> https://guug.de/veranstaltungen/ffg2016/slides/Heinz%20Mauelshagen%20-%20Neueste%20Entwicklungen%20in%20LVM%20RAID.pdf
>  
> --
> Jason Czerak 
>  
> _______________________________________________
> 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/

Re: [linux-lvm] LVM feature parity with MD

[Fabian Herschel]

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Can LVM doing a delta sync and does LVM have something like a bitamp to 
show which parts are in sync and which needs a sync?

On 04/26/2016 08:25 PM, Jason Czerak wrote:
> I found the presentation linked below regarding LVM's new features and I'm wondering if anyone shed any light on when these may become stable? Specifically the RAID0 reshaping.
>
> https://guug.de/veranstaltungen/ffg2016/slides/Heinz%20Mauelshagen%20-%20Neueste%20Entwicklungen%20in%20LVM%20RAID.pdf
>
> --
> Jason Czerak
>
>
>
>
> _______________________________________________
> 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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Re: [linux-lvm] LVM feature parity with MD

[Zdenek Kabelac]

On 2.5.2016 13:03, Fabian Herschel wrote:
> Can LVM doing a delta sync and does LVM have something like a bitamp to show
> which parts are in sync and which needs a sync?
>

Hi

lvm uses small metadata LV with each raid1 leg - which holds the bitmap about 
individual regionsize areas in sync.

So when there is 'crash' only async areas are synced again after array restart.

Regards

Zdenek

Re: [linux-lvm] LVM feature parity with MD

[Brassow Jonathan]

> On May 3, 2016, at 3:34 AM, Zdenek Kabelac <zkabelac@redhat.com> wrote:
> 
> On 2.5.2016 13:03, Fabian Herschel wrote:
>> Can LVM doing a delta sync and does LVM have something like a bitamp to show
>> which parts are in sync and which needs a sync?
>> 
> 
> Hi
> 
> lvm uses small metadata LV with each raid1 leg - which holds the bitmap about individual regionsize areas in sync.
> 
> So when there is 'crash' only async areas are synced again after array restart.

In fact, it works very much the same way as MD, because it uses the same kernel module to perform it.  You can also check-out ‘lvconvert —splitmirror —trackchanges …’.  This would allow you to temporarily split off a RAID1 leg and then reintroduce it later while only updating the portions that have changed.

When you use the ‘raid1’ segment type (the default upstream and in RHEL7) and not the ‘mirror’ segment type, a transient failure can be recovered while only resyncing the changes.

 brassow