Re: [ClusterLabs] DRBD or SAN ?

[Digimer]

On 2017-07-18 03:11 PM, Lentes, Bernd wrote:
> 
>>
>> If you have DRBD (PV) -> Clustered VG -> LV per VM, and you have
>> dual-primary DRBD, you can already do a live migration.
>>
> 
> 
> What is about PV -> clustered VG -> LV -> DRBD ?

I don't understand how that would work... The goal of clvmd is to ensure
changes to the VG (on a shared PV, like a LUN or DRBD) happen on all
nodes at the same time.

-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould

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Re: [ClusterLabs] DRBD or SAN ?

[Lentes, Bernd]

> 
> If you have DRBD (PV) -> Clustered VG -> LV per VM, and you have
> dual-primary DRBD, you can already do a live migration.
> 


What is about PV -> clustered VG -> LV -> DRBD ?


Bernd
 

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons Enhsen
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671


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Re: [ClusterLabs] DRBD or SAN ?

[Digimer]

On 2017-07-18 02:29 PM, Lentes, Bernd wrote:
> 
>>>
>>> On SLES 11 SP4 HAE DRBD 8.4 is available. Do i need a cluster fs on top of a
>>> dual primary DRBD ?
>>> I assume.
>>>
>>>
>>> Bernd
>>
>> Depends.
>>
>> If you want to have a shared FS, yes. If you want to back VMs though, we
>> use clustered LVM to manage the DRBD space, creating per-VM LVs, and
>> then use the resource manager to manage the servers. This keeps the LVM
>> data in sync and avoids the cost of cluster locking.
>>
> 
> Hi Digimer,
> 
> just to be clear: we have already cLVM because i'd like to store the vm's in 
> plain logical volumes, without fs.
> That's running already. If i want live migration of vm's which resides on the 
> plain logical volumes in conjunction with DRBD
> (DRBD on top of the lv ?) i don't need a cluster fs ?
> 
> Thanks for the clarification.
> 
> 
> Bernd

If you have DRBD (PV) -> Clustered VG -> LV per VM, and you have
dual-primary DRBD, you can already do a live migration.

-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould

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Re: [ClusterLabs] DRBD or SAN ?

[Lentes, Bernd]

>> 
>> On SLES 11 SP4 HAE DRBD 8.4 is available. Do i need a cluster fs on top of a
>> dual primary DRBD ?
>> I assume.
>> 
>> 
>> Bernd
> 
> Depends.
> 
> If you want to have a shared FS, yes. If you want to back VMs though, we
> use clustered LVM to manage the DRBD space, creating per-VM LVs, and
> then use the resource manager to manage the servers. This keeps the LVM
> data in sync and avoids the cost of cluster locking.
> 

Hi Digimer,

just to be clear: we have already cLVM because i'd like to store the vm's in 
plain logical volumes, without fs.
That's running already. If i want live migration of vm's which resides on the 
plain logical volumes in conjunction with DRBD
(DRBD on top of the lv ?) i don't need a cluster fs ?

Thanks for the clarification.


Bernd
 

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons Enhsen
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671


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Re: [ClusterLabs] DRBD or SAN ?

[Digimer]

On 2017-07-18 01:41 PM, Lentes, Bernd wrote:
> 
> 
> 

>>>
>>> Is with DRBD and Virtual Machines live migration possible ?
>>>
>>>
>>> Bernd
>>
>> yes, but dual-primary is needed (this is how the Anvil! does live
>> migration). With DRBD 9, you can set it up to momentarily do
>> dual-primary to support live migration, though I have not used this
>> myself yet.
>>
>> With dual-primary, you need to be sure a few things are in place (ie:
>> proper fencing, but you need that anyway, a cluster resource manager, etc).
>>
> 
> On SLES 11 SP4 HAE DRBD 8.4 is available. Do i need a cluster fs on top of a 
> dual primary DRBD ?
> I assume.
> 
> 
> Bernd

Depends.

If you want to have a shared FS, yes. If you want to back VMs though, we
use clustered LVM to manage the DRBD space, creating per-VM LVs, and
then use the resource manager to manage the servers. This keeps the LVM
data in sync and avoids the cost of cluster locking.

-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould

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Re: [ClusterLabs] DRBD or SAN ?

[Lentes, Bernd]

>>>
>> 
>> Is with DRBD and Virtual Machines live migration possible ?
>> 
>> 
>> Bernd
> 
> yes, but dual-primary is needed (this is how the Anvil! does live
> migration). With DRBD 9, you can set it up to momentarily do
> dual-primary to support live migration, though I have not used this
> myself yet.
> 
> With dual-primary, you need to be sure a few things are in place (ie:
> proper fencing, but you need that anyway, a cluster resource manager, etc).
> 

On SLES 11 SP4 HAE DRBD 8.4 is available. Do i need a cluster fs on top of a 
dual primary DRBD ?
I assume.


Bernd
 

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons Enhsen
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671


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Re: [ClusterLabs] DRBD or SAN ?

[emmanuel segura]

yes, if you are using drbd in master/slave, first promote the resource to
master and then start vm on the node, if you use drbd in multimaster, only
start the vm when drbd is started.

Use SAN, with multipath.

2017-07-18 16:34 GMT+02:00 Lentes, Bernd :

>
>
> - On Jul 17, 2017, at 11:51 AM, Bernd Lentes bernd.lentes@helmholtz-
> muenchen.de wrote:
>
> > Hi,
> >
> > i established a two node cluster with two HP servers and SLES 11 SP4.
> I'd like
> > to start now with a test period. Resources are virtual machines. The vm's
> > reside on a FC SAN. The SAN has two power supplies, two storage
> controller, two
> > network interfaces for configuration. Each storage controller has two FC
> > connectors. On each server i have one FC controller with two connectors
> in a
> > multipath configuration. Each connector from the SAN controller inside
> the
> > server is connected to a different storage controller from the SAN. But
> isn't a
> > SAN, despite all that redundancy, a SPOF ?
> > I'm asking myself if a DRBD configuration wouldn't be more redundant and
> high
> > available. There i have two completely independent instances of the vm.
> > We have one web application with a databse which is really crucial for
> us.
> > Downtime should be maximum one or two hours, if longer we run in trouble.
> > Is DRBD in conjuction with a database (MySQL or Postgres) possible ?
> >
> >
> > Bernd
> >
>
> Is with DRBD and Virtual Machines live migration possible ?
>
>
> Bernd
>
>
> Helmholtz Zentrum Muenchen
> Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
> Ingolstaedter Landstr. 1
> 85764 Neuherberg
> www.helmholtz-muenchen.de
> Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
> Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons
> Enhsen
> Registergericht: Amtsgericht Muenchen HRB 6466
> USt-IdNr: DE 129521671
>
>
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> Users mailing list: Users@clusterlabs.org
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> Bugs: http://bugs.clusterlabs.org
>



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Re: [ClusterLabs] DRBD or SAN ?

[Digimer]

On 2017-07-18 10:34 AM, Lentes, Bernd wrote:
> 
> 
> - On Jul 17, 2017, at 11:51 AM, Bernd Lentes 
> bernd.len...@helmholtz-muenchen.de wrote:
> 
>> Hi,
>>
>> i established a two node cluster with two HP servers and SLES 11 SP4. I'd 
>> like
>> to start now with a test period. Resources are virtual machines. The vm's
>> reside on a FC SAN. The SAN has two power supplies, two storage controller, 
>> two
>> network interfaces for configuration. Each storage controller has two FC
>> connectors. On each server i have one FC controller with two connectors in a
>> multipath configuration. Each connector from the SAN controller inside the
>> server is connected to a different storage controller from the SAN. But 
>> isn't a
>> SAN, despite all that redundancy, a SPOF ?
>> I'm asking myself if a DRBD configuration wouldn't be more redundant and high
>> available. There i have two completely independent instances of the vm.
>> We have one web application with a databse which is really crucial for us.
>> Downtime should be maximum one or two hours, if longer we run in trouble.
>> Is DRBD in conjuction with a database (MySQL or Postgres) possible ?
>>
>>
>> Bernd
>>
> 
> Is with DRBD and Virtual Machines live migration possible ?
> 
> 
> Bernd

yes, but dual-primary is needed (this is how the Anvil! does live
migration). With DRBD 9, you can set it up to momentarily do
dual-primary to support live migration, though I have not used this
myself yet.

With dual-primary, you need to be sure a few things are in place (ie:
proper fencing, but you need that anyway, a cluster resource manager, etc).

-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould

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Re: [ClusterLabs] DRBD or SAN ?

[Digimer]

On 2017-07-18 04:08 AM, Dmitri Maziuk wrote:
> On 7/17/2017 2:07 PM, Chris Adams wrote:
> 
>> However, just like RAID is not a replacement for backups, DRBD is IMHO
>> not a replacement for database replication.  DRBD would just replicate
>> database files, so if for example file corruption would be copied from
>> host to host.  When something provides a native replication system, it
>> is probably better to use that (or at least use it at one level).
> 
> Since DRBD is RAID-1, you need double the drives either way, no
> advantage over two independent copies -- only the potential for
> replicating errors. You probably need a 10G pipe, with associated costs,
> for "no performance penalty" DRBD while native replication tends to work
> OK over slower links.

That's... an interesting take. I strongly disagree.

We've deployed dozens and dozens of DRBD-backed clusters and only one
client needed 10 Gbps. Most users, in our experience, need lower
latency, not large throughput, and a good 1Gbps network has sub-ms
latency, faster than even 15krpm sas drives.

As for replication errors, well, you're judging something without using
it, I have to conclude. In all our years using DRBD, we have never had a
data corruption issue or any other problem induced by DRBD. We sure have
been saved by in on several occasions.

Having data synchronously replicated between two mechanically and
electrically isolated systems is fantastic protection.

> At this point a 2U SuperMicro chassis gives you 2 SSD slots for system
> and ZiL/L2ARC plus 12 spinning rust slots for a pretty large database...

Now speaking of trouble, I've been let down by Supermicro equipment
numerous times, and won't touch them with a ten foot pole anymore.

> That won't work for VM images, for that you'll need NAS or DRBD but IMO
> NAS wins. Realistically, a hard drive failure is the most likely kind of
> failure you're looking at, and initiating a full storage cluster
> failover for that is probably not a good idea. So you might want a
> drive-level redundancy on at least the primary node, at which point
> dual-ported SAS drives in external shelves become economical, even with
> a couple of dual-ported SAS SSDs for caches. So ZFS setup I linked to
> above actually comes with fewer moving parts and all the handy features
> absent from previous-gen filesystems.
> 
> Dima

A NAS is a single point of failure, and after years of managing dozens
of clusters, I could rattle off quite a number of failure scenarios
we've seen in the field. Here are a few;

* Failed voltage regulators taking a node offline without warning.
* Failed backplanes causing multiple disks to be lost.
* User error destroying RAID arrays.
* Bad components used during upgrades causing a node to be offline until
a new part is delivered

Etc.

-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould

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Re: [ClusterLabs] DRBD or SAN ?

[Ken Gaillot]

On 07/18/2017 09:34 AM, Lentes, Bernd wrote:
> 
> 
> - On Jul 17, 2017, at 11:51 AM, Bernd Lentes 
> bernd.len...@helmholtz-muenchen.de wrote:
> 
>> Hi,
>>
>> i established a two node cluster with two HP servers and SLES 11 SP4. I'd 
>> like
>> to start now with a test period. Resources are virtual machines. The vm's
>> reside on a FC SAN. The SAN has two power supplies, two storage controller, 
>> two
>> network interfaces for configuration. Each storage controller has two FC
>> connectors. On each server i have one FC controller with two connectors in a
>> multipath configuration. Each connector from the SAN controller inside the
>> server is connected to a different storage controller from the SAN. But 
>> isn't a
>> SAN, despite all that redundancy, a SPOF ?
>> I'm asking myself if a DRBD configuration wouldn't be more redundant and high
>> available. There i have two completely independent instances of the vm.
>> We have one web application with a databse which is really crucial for us.
>> Downtime should be maximum one or two hours, if longer we run in trouble.
>> Is DRBD in conjuction with a database (MySQL or Postgres) possible ?
>>
>>
>> Bernd
>>
> 
> Is with DRBD and Virtual Machines live migration possible ?

Yes, definitely. In the past, I've even live-migrated a VM with 24GB RAM
over 10gigE very quickly, with LVM over DRBD underneath.

> Bernd
>  
> 
> Helmholtz Zentrum Muenchen
> Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
> Ingolstaedter Landstr. 1
> 85764 Neuherberg
> www.helmholtz-muenchen.de
> Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
> Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons 
> Enhsen
> Registergericht: Amtsgericht Muenchen HRB 6466
> USt-IdNr: DE 129521671

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Re: [ClusterLabs] DRBD or SAN ?

[Lentes, Bernd]

- On Jul 17, 2017, at 11:51 AM, Bernd Lentes 
bernd.len...@helmholtz-muenchen.de wrote:

> Hi,
> 
> i established a two node cluster with two HP servers and SLES 11 SP4. I'd like
> to start now with a test period. Resources are virtual machines. The vm's
> reside on a FC SAN. The SAN has two power supplies, two storage controller, 
> two
> network interfaces for configuration. Each storage controller has two FC
> connectors. On each server i have one FC controller with two connectors in a
> multipath configuration. Each connector from the SAN controller inside the
> server is connected to a different storage controller from the SAN. But isn't 
> a
> SAN, despite all that redundancy, a SPOF ?
> I'm asking myself if a DRBD configuration wouldn't be more redundant and high
> available. There i have two completely independent instances of the vm.
> We have one web application with a databse which is really crucial for us.
> Downtime should be maximum one or two hours, if longer we run in trouble.
> Is DRBD in conjuction with a database (MySQL or Postgres) possible ?
> 
> 
> Bernd
> 

Is with DRBD and Virtual Machines live migration possible ?


Bernd
 

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrer: Prof. Dr. Guenther Wess, Heinrich Bassler, Dr. Alfons Enhsen
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671


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Re: [ClusterLabs] DRBD or SAN ?

[Dmitri Maziuk]

On 7/17/2017 2:07 PM, Chris Adams wrote:


However, just like RAID is not a replacement for backups, DRBD is IMHO
not a replacement for database replication.  DRBD would just replicate
database files, so if for example file corruption would be copied from
host to host.  When something provides a native replication system, it
is probably better to use that (or at least use it at one level).


Since DRBD is RAID-1, you need double the drives either way, no 
advantage over two independent copies -- only the potential for 
replicating errors. You probably need a 10G pipe, with associated costs, 
for "no performance penalty" DRBD while native replication tends to work 
OK over slower links.


At this point a 2U SuperMicro chassis gives you 2 SSD slots for system 
and ZiL/L2ARC plus 12 spinning rust slots for a pretty large database...


That won't work for VM images, for that you'll need NAS or DRBD but IMO 
NAS wins. Realistically, a hard drive failure is the most likely kind of 
failure you're looking at, and initiating a full storage cluster 
failover for that is probably not a good idea. So you might want a 
drive-level redundancy on at least the primary node, at which point 
dual-ported SAS drives in external shelves become economical, even with 
a couple of dual-ported SAS SSDs for caches. So ZFS setup I linked to 
above actually comes with fewer moving parts and all the handy features 
absent from previous-gen filesystems.


Dima


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