Is iSCSI performance better for VMs on the selected Host?

Hi all, I am planning to add block storage (iSCSI) to my oVirt environment. I just stumbled across this point from the oVirt Documentation: "6. Select an active host in the Use Host field. If this is not the first data domain in a data center, you must select the data center's SPM host. Important: All communication to the storage domain is through the selected host and not directly from the oVirt Engine." (you find it here: https://www.ovirt.org/documentation/admin-guide/chap-Storage.html#adding-blo...) So my question is: Is there a significant performance advantage for VMs using the storage that are running on that "selected host"? Because if this is the case, I would connect all my host machines to the dedicated storage network, create multiple data domains and "split" my iSCSI storage server(s) among those domains. If it is not the case, I would only have my storage server(s) and one of my hosts in the storage network. This also has implications on the dimensions (and cost!) of the switch that I use for the storage network, so I would be grateful if someone has any insight. Thanks

Hello Sebastian, you missed a bit from the paragraph Important: All communication to the storage domain is through the selected host and not directly from the oVirt Engine. At least one active host must exist in the system and be attached to the chosen data center. All hosts must have access to the storage device before the storage domain can be configured. Regards, Paul S. ________________________________________ From: sebastian.freitag@aptiv.com <sebastian.freitag@aptiv.com> Sent: 28 March 2019 16:42 To: users@ovirt.org Subject: [ovirt-users] Is iSCSI performance better for VMs on the selected Host? Hi all, I am planning to add block storage (iSCSI) to my oVirt environment. I just stumbled across this point from the oVirt Documentation: "6. Select an active host in the Use Host field. If this is not the first data domain in a data center, you must select the data center's SPM host. Important: All communication to the storage domain is through the selected host and not directly from the oVirt Engine." (you find it here: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ovirt....) So my question is: Is there a significant performance advantage for VMs using the storage that are running on that "selected host"? Because if this is the case, I would connect all my host machines to the dedicated storage network, create multiple data domains and "split" my iSCSI storage server(s) among those domains. If it is not the case, I would only have my storage server(s) and one of my hosts in the storage network. This also has implications on the dimensions (and cost!) of the switch that I use for the storage network, so I would be grateful if someone has any insight. Thanks _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ovirt.... oVirt Code of Conduct: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ovirt.... List Archives: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.ovir... To view the terms under which this email is distributed, please go to:- http://leedsbeckett.ac.uk/disclaimer/email/

I think it was more that I had trouble understanding it. Does it mean the the "selected host" during setup is only for config and meta data and that all the hosts communicate directly with the storage server for actual "payload" iSCSI data exchange?

Yes, you are right. You have to enable also "Multi Host support on your iSCSI target". Oliver
Am 29.03.2019 um 14:15 schrieb sebastian.freitag@aptiv.com:
I think it was more that I had trouble understanding it.
Does it mean the the "selected host" during setup is only for config and meta data and that all the hosts communicate directly with the storage server for actual "payload" iSCSI data exchange? _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/site/privacy-policy/ oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/E64FJCU7NJNZJH...

Yes the SPM controls the metadata, such as creating,deleting virtual disks,snapshots,templates. https://www.ovirt.org/documentation/admin-guide/chap-Data_Centers.html Regards, Paul S. ________________________________________ From: sebastian.freitag@aptiv.com <sebastian.freitag@aptiv.com> Sent: 29 March 2019 13:15 To: users@ovirt.org Subject: [ovirt-users] Re: Is iSCSI performance better for VMs on the selected Host? I think it was more that I had trouble understanding it. Does it mean the the "selected host" during setup is only for config and meta data and that all the hosts communicate directly with the storage server for actual "payload" iSCSI data exchange? _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ovirt.... oVirt Code of Conduct: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ovirt.... List Archives: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.ovir... To view the terms under which this email is distributed, please go to:- http://leedsbeckett.ac.uk/disclaimer/email/
participants (3)
-
Oliver Riesener
-
sebastian.freitag@aptiv.com
-
Staniforth, Paul