[Users] Storage domain weirdness (or design)

Hi, I see a strange behaviour - Setup: 1 ovirtmgmt / ovirt-engine hsot 2 ovirt nodes / HVs 2 storage domains in same cluster & DC HV1 => storage domain 1 (master) HV2 => storage domain 2 Issue: When I create a host with say ~40GB disk to be on HV2/storage_domain_2, it does that via HV1 ? Why is that ? I realize a storage domain is "attached to the cluster/dc", however, when creating the VM I explicitly seleted to only run on HV2, so why would it still create the disk via HV1 ? The mgmt network (for now) is only just that, a mgmt network, not meant to create 40 GB disks (dd from /dev/null) over NFS .. it's currently only a 100mbit switch Question: How, if at all, can I make Ovirt create the Disk from the host where it's meant to run on ? Thanks, Alex -- | RHCE | Senior Systems Engineer | www.vcore.co | www.vsearchcloud.com |

Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters. The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on. Regards, Maor On 01/17/2013 05:28 PM, Alex Leonhardt wrote: > Hi, > > I see a strange behaviour - > > > Setup: > > 1 ovirtmgmt / ovirt-engine hsot > 2 ovirt nodes / HVs > 2 storage domains in same cluster & DC > > HV1 => storage domain 1 (master) > HV2 => storage domain 2 > > Issue: > > When I create a host with say ~40GB disk to be on HV2/storage_domain_2, > it does that via HV1 ? Why is that ? I realize a storage domain is > "attached to the cluster/dc", however, when creating the VM I explicitly > seleted to only run on HV2, so why would it still create the disk via > HV1 ? The mgmt network (for now) is only just that, a mgmt network, not > meant to create 40 GB disks (dd from /dev/null) over NFS .. it's > currently only a 100mbit switch > > Question: > > How, if at all, can I make Ovirt create the Disk from the host where > it's meant to run on ? 1. You can create a new Data Center and separate the host and the sotrage domain to be used only there. 2. You can move your current SPM host to maintenance which will cause your other host to become SPM and write the data to the storage domain it self. What is the reason you want it to act like this? > > > Thanks, > Alex > > > -- > > | RHCE | Senior Systems Engineer | www.vcore.co <http://www.vcore.co> | > www.vsearchcloud.com <http://www.vsearchcloud.com> | > > > _______________________________________________ > Users mailing list > Users@ovirt.org > http://lists.ovirt.org/mailman/listinfo/users >

This is a multi-part message in MIME format. --------------030502000706000808000203 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hiya, Yes i can choose the storage domain, but I cannot force the host that is to be used for creating it. Even with 1Gbit network, creating a 80GB disk / 40 GB disk is still significantly longer process than actually required when doing a "dd" of /dev/null over the network. Is it possible to manually change who is SPM master, create the disks/VMs required, and change it back ? How would that change affect the running VMs / would they try to migrate to the other HV ? Alex On 01/17/2013 07:39 PM, Maor Lipchuk wrote:
Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters.
The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on.
Regards, Maor
--------------030502000706000808000203 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit <html> <head> <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <font size="-1"><font face="Tahoma">Hiya,<br> <br> Yes i can choose the storage domain, but I cannot force the host that is to be used for creating it. Even with 1Gbit network, creating a 80GB disk / 40 GB disk is still significantly longer process than actually required when doing a "dd" of /dev/null over the network. <br> <br> Is it possible to manually change who is SPM master, create the disks/VMs required, and change it back ? How would that change affect the running VMs / would they try to migrate to the other HV ? <br> <br> Alex<br> <br> </font></font><br> On 01/17/2013 07:39 PM, Maor Lipchuk wrote: <blockquote cite="mid:50F85373.4080101@redhat.com" type="cite"> <pre wrap="">Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters. The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on. Regards, Maor </pre> </blockquote> </body> </html> --------------030502000706000808000203--

Hi Alex, See my last respond, I add a comment inline there. See my comments inline Regards, Maor. On 01/17/2013 10:04 PM, Alex Leonhardt wrote:
Hiya,
Yes i can choose the storage domain, but I cannot force the host that is to be used for creating it. Even with 1Gbit network, creating a 80GB disk / 40 GB disk is still significantly longer process than actually required when doing a "dd" of /dev/null over the network.
Is it possible to manually change who is SPM master, create the disks/VMs required, and change it back ? You can maintain your SPM host, and active it back again, this will change the SPM to be the other host which you want. How would that change affect the running VMs / would they try to migrate to the other HV ? The VM migration will still be under the same cluster.
SPM is simply used to write to the storage domains, one of the reasons we use the SPM is to avoid collisions when hosts write to the same storage domain.
Alex
On 01/17/2013 07:39 PM, Maor Lipchuk wrote:
Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters.
The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on.
Regards, Maor

Hmmm, but if I put the SPM host into Maint mode, then all the VMs would either be migrated or (in my case, all set to manual) not available during that time, correct ? Would changing the SPM priority in the host config have the desired effect w/o putting the host into Maint mode ? Or can I only do that when the host is in Maint mode ? On 17 January 2013 20:42, Maor Lipchuk <mlipchuk@redhat.com> wrote:
Hi Alex, See my last respond, I add a comment inline there. See my comments inline
Regards, Maor.
On 01/17/2013 10:04 PM, Alex Leonhardt wrote:
Hiya,
Yes i can choose the storage domain, but I cannot force the host that is to be used for creating it. Even with 1Gbit network, creating a 80GB disk / 40 GB disk is still significantly longer process than actually required when doing a "dd" of /dev/null over the network.
Is it possible to manually change who is SPM master, create the disks/VMs required, and change it back ? You can maintain your SPM host, and active it back again, this will change the SPM to be the other host which you want. How would that change affect the running VMs / would they try to migrate to the other HV ? The VM migration will still be under the same cluster.
SPM is simply used to write to the storage domains, one of the reasons we use the SPM is to avoid collisions when hosts write to the same storage domain.
Alex
On 01/17/2013 07:39 PM, Maor Lipchuk wrote:
Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters.
The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on.
Regards, Maor
-- | RHCE | Senior Systems Engineer | www.vcore.co | www.vsearchcloud.com |

I was just thinking - maybe adding a setting to storage domains who's the "master" for that specific storage domain would get around this ? e.g. storage_domain_1 => master = HV1, storage_domain_2 => master = HV2, etc. etc. What do you think ? Alex On 18 January 2013 09:34, Alex Leonhardt <alex.tuxx@gmail.com> wrote:
Hmmm, but if I put the SPM host into Maint mode, then all the VMs would either be migrated or (in my case, all set to manual) not available during that time, correct ?
Would changing the SPM priority in the host config have the desired effect w/o putting the host into Maint mode ? Or can I only do that when the host is in Maint mode ?
On 17 January 2013 20:42, Maor Lipchuk <mlipchuk@redhat.com> wrote:
Hi Alex, See my last respond, I add a comment inline there. See my comments inline
Regards, Maor.
On 01/17/2013 10:04 PM, Alex Leonhardt wrote:
Hiya,
Yes i can choose the storage domain, but I cannot force the host that is to be used for creating it. Even with 1Gbit network, creating a 80GB disk / 40 GB disk is still significantly longer process than actually required when doing a "dd" of /dev/null over the network.
Is it possible to manually change who is SPM master, create the disks/VMs required, and change it back ? You can maintain your SPM host, and active it back again, this will change the SPM to be the other host which you want. How would that change affect the running VMs / would they try to migrate to the other HV ? The VM migration will still be under the same cluster.
SPM is simply used to write to the storage domains, one of the reasons we use the SPM is to avoid collisions when hosts write to the same storage domain.
Alex
On 01/17/2013 07:39 PM, Maor Lipchuk wrote:
Hi Alex, The storage domains are part of the Data Center, and should not be related to clusters. Clusters are used for migrating VMs, which are the qemu processes, between hosts. Disks are created on the storage domains regardless to clusters.
The host which write the data in the storage domain to create the disk is the SPM. You should have only one SPM in each Data Center (You can spot which host is your SPM by looking at the SPM column in the hosts tab) When you create a disk you should be able to choose the storage domain which you want the disk to be created on.
Regards, Maor
--
| RHCE | Senior Systems Engineer | www.vcore.co | www.vsearchcloud.com |
-- | RHCE | Senior Systems Engineer | www.vcore.co | www.vsearchcloud.com |

Hi Alex, What that you suggest is pretty similar to have two different Data Center. One with host HV1 and storage domain 1. The other with storage_domain_2 and HV2 host. This might work, and your two hosts will be SPM, one for DC1 and the other for DC2 I'm not sure that I follow your suggestion about setting the storage domains who is the master (the SPM will still stay the same host as before). Regards, Maor On 01/18/2013 11:36 AM, Alex Leonhardt wrote:
I was just thinking - maybe adding a setting to storage domains who's the "master" for that specific storage domain would get around this ?
e.g. storage_domain_1 => master = HV1, storage_domain_2 => master = HV2, etc. etc.
What do you think ?
Alex
On 18 January 2013 09:34, Alex Leonhardt <alex.tuxx@gmail.com <mailto:alex.tuxx@gmail.com>> wrote:
Hmmm, but if I put the SPM host into Maint mode, then all the VMs would either be migrated or (in my case, all set to manual) not available during that time, correct ?
Would changing the SPM priority in the host config have the desired effect w/o putting the host into Maint mode ? Or can I only do that when the host is in Maint mode ?
On 17 January 2013 20:42, Maor Lipchuk <mlipchuk@redhat.com <mailto:mlipchuk@redhat.com>> wrote:
Hi Alex, See my last respond, I add a comment inline there. See my comments inline
Regards, Maor.
On 01/17/2013 10:04 PM, Alex Leonhardt wrote: > Hiya, > > Yes i can choose the storage domain, but I cannot force the host that is > to be used for creating it. Even with 1Gbit network, creating a 80GB > disk / 40 GB disk is still significantly longer process than actually > required when doing a "dd" of /dev/null over the network. > > Is it possible to manually change who is SPM master, create the > disks/VMs required, and change it back ? You can maintain your SPM host, and active it back again, this will change the SPM to be the other host which you want. > How would that change affect the running VMs / would they try to migrate to the other HV ? The VM migration will still be under the same cluster.
SPM is simply used to write to the storage domains, one of the reasons we use the SPM is to avoid collisions when hosts write to the same storage domain.
> > Alex > > > On 01/17/2013 07:39 PM, Maor Lipchuk wrote: >> Hi Alex, >> The storage domains are part of the Data Center, and should not be >> related to clusters. >> Clusters are used for migrating VMs, which are the qemu processes, >> between hosts. >> Disks are created on the storage domains regardless to clusters. >> >> The host which write the data in the storage domain to create the disk >> is the SPM. >> You should have only one SPM in each Data Center (You can spot which >> host is your SPM by looking at the SPM column in the hosts tab) >> When you create a disk you should be able to choose the storage domain >> which you want the disk to be created on. >> >> Regards, >> Maor
--
| RHCE | Senior Systems Engineer | www.vcore.co <http://www.vcore.co> | www.vsearchcloud.com <http://www.vsearchcloud.com> |
--
| RHCE | Senior Systems Engineer | www.vcore.co <http://www.vcore.co> | www.vsearchcloud.com <http://www.vsearchcloud.com> |

Hmmm, but if I put the SPM host into Maint mode, then all the VMs would either be migrated or (in my case, all set to manual) not available during that time, correct ? Yes, the other way that you can do to change your SPM host is to ssh into your SPM host and restart your VDSM service (service vdsmd restart). I would recommend you, first to check if there are no running tasks
Hi Alex, Please, see my comments inline. Regards, Maor On 01/18/2013 11:34 AM, Alex Leonhardt wrote: there (vdsClient 0 getAllTasksStatuses), simply because restart of VDSM will cancel them.
Would changing the SPM priority in the host config have the desired effect w/o putting the host into Maint mode ? Or can I only do that when the host is in Maint mode ?
You can't change your SPM host while your host is up and running.
On 17 January 2013 20:42, Maor Lipchuk <mlipchuk@redhat.com <mailto:mlipchuk@redhat.com>> wrote:
Hi Alex, See my last respond, I add a comment inline there. See my comments inline
Regards, Maor.
On 01/17/2013 10:04 PM, Alex Leonhardt wrote: > Hiya, > > Yes i can choose the storage domain, but I cannot force the host that is > to be used for creating it. Even with 1Gbit network, creating a 80GB > disk / 40 GB disk is still significantly longer process than actually > required when doing a "dd" of /dev/null over the network. > > Is it possible to manually change who is SPM master, create the > disks/VMs required, and change it back ? You can maintain your SPM host, and active it back again, this will change the SPM to be the other host which you want. > How would that change affect the running VMs / would they try to migrate to the other HV ? The VM migration will still be under the same cluster.
SPM is simply used to write to the storage domains, one of the reasons we use the SPM is to avoid collisions when hosts write to the same storage domain.
> > Alex > > > On 01/17/2013 07:39 PM, Maor Lipchuk wrote: >> Hi Alex, >> The storage domains are part of the Data Center, and should not be >> related to clusters. >> Clusters are used for migrating VMs, which are the qemu processes, >> between hosts. >> Disks are created on the storage domains regardless to clusters. >> >> The host which write the data in the storage domain to create the disk >> is the SPM. >> You should have only one SPM in each Data Center (You can spot which >> host is your SPM by looking at the SPM column in the hosts tab) >> When you create a disk you should be able to choose the storage domain >> which you want the disk to be created on. >> >> Regards, >> Maor
--
| RHCE | Senior Systems Engineer | www.vcore.co <http://www.vcore.co> | www.vsearchcloud.com <http://www.vsearchcloud.com> |
participants (2)
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Alex Leonhardt
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Maor Lipchuk