Hi guys, There have been a few related questions already that I could find, but I did not find anything relating to my specific use case. Currently it is not possible to mix local storage with shared storage in the same datacenter. The reason seems to be because of the storage pool manager (SPM). This is a role in the datacenter provided to one specific host. While I understand that this makes having local storage impossible, I believe there is a use case to have local storage in a shared storage datacenter.

Consider the following: I have a few applications that require 1 milli second latency and at most 2 milli second.

That is not consistenly achievable with shared storage, to that end I added flash storage to a few hypervisors.

About 5% of my servers require this and are not that resource hungry to require a dedicated physical server. That same 5% also has no requirement to be migrated if a host fails. So in short I have 5 heavy hosts running ovirt with a shared storage domain on NFS for 95% of my servers. All running fine, but I am now unable to run my remaining 5%.

To finish up my summary I have been testing various virtualization technologies, like VmWare and Hyper-V. They allow such configurations as I mentioned. I already had some chat on irc with various guys and they suggested that I put this on the mailing list, so here goes. My suggestion would be to evoluate from SPM to SDM.

SDM stands for Storage Domain Manager. This would create the possibility to have all nodes in the datacenter participate in the storage handling. A extra benefit would be that local storage could be added. What do you think?

Thanks for reading. Kind regards, Mike van Goor _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users

Hi Yaniv, Op 30-10-2016 om 11:35 schreef Yaniv Kaul: > > > On Sun, Oct 30, 2016 at 12:02 PM, Mike (maillinglists) > <maillist(a)probie.nl <mailto:maillist@probie.nl>> wrote: > > Hi guys, > > There have been a few related questions already that I could find, > but I did not find anything relating to my specific use case. > > Currently it is not possible to mix local storage with shared > storage in the same datacenter. > The reason seems to be because of the storage pool manager (SPM). > This is a role in the datacenter provided to one specific host. > > While I understand that this makes having local storage impossible, > I believe there is a use case to have local storage in a shared > storage datacenter. > > > Indeed, this is one of the more appealing use cases. There are others s > well. > > > Consider the following: > I have a few applications that require 1 milli second latency and at > most 2 milli second. > > > For read, write or both? > Both I'm afraid. > > > That is not consistenly achievable with shared storage, to that end > I added flash storage to a few hypervisors. > > > You could have flash on your shared storage. > The problem with shared flash storage is the storage network required in between. I have seen shared NFS storage at 1ms latency, but that has not been stable and this application requires stable 1ms latencies. > > > About 5% of my servers require this and are not that resource hungry > to require a dedicated physical server. > That same 5% also has no requirement to be migrated if a host fails. > > So in short I have 5 heavy hosts running ovirt with a shared storage > domain on NFS for 95% of my servers. > All running fine, but I am now unable to run my remaining 5%. > > > Perhaps, if there are no HA requirements, those VMs with local domain > needs can be in their own DC, a local one? If it's just 5%, shouldn't be > much of an effort? > Can a host be in 2 datacenters?

I was not aware of this and I will investigate. > > > To finish up my summary I have been testing various virtualization > technologies, like VmWare and Hyper-V. > They allow such configurations as I mentioned. > > I already had some chat on irc with various guys and they suggested > that I put this on the mailing list, so here goes. > > My suggestion would be to evoluate from SPM to SDM. > > > Easier said than done... We have worked on this for quite some time, > it's not as easy as one might think. > I appreciate your honousty, but still hope this can be achieved. > > > SDM stands for Storage Domain Manager. > This would create the possibility to have all nodes in the > datacenter participate in the storage handling. > A extra benefit would be that local storage could be added. > > What do you think? > > > There are other use cases we think flash on the host can be used, some > may be of use for your use case. > For example, dm-cache[1]. > > We are still looking at this. I think Gluster already can make use it > for cache, for example. > Y. > Gluster is an angle we are investigating, but takes time to look into. Thanks! > > [1] https://people.redhat.com/mskinner/rhug/q1.2016/dm-cache.pdf > Thanks! > > > > Thanks for reading. > > Kind regards, > Mike van Goor > _______________________________________________ > Users mailing list > Users(a)ovirt.org <mailto:Users@ovirt.org> > http://lists.ovirt.org/mailman/listinfo/users > <http://lists.ovirt.org/mailman/listinfo/users> > > >

Op 30-10-2016 om 12:50 schreef Yaniv Kaul: > > Perhaps, if there are no HA requirements, those VMs with local > domain > needs can be in their own DC, a local one? If it's just 5%, > shouldn't be > much of an effort? > > Can a host be in 2 datacenters? > > > No, I suggested to dedicate a host (or several) with their own local DC > for those 5%. > Y. I have 5 hosts and dedicating 2 hosts for 5% seems a gigantic waste if you ask me. So I cannot do that.

_______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users

On Sun, Oct 30, 2016 at 8:49 PM, Mike <maillist(a)probie.nl&gt; wrote: > Op 30-10-2016 om 12:50 schreef Yaniv Kaul: >> >> Perhaps, if there are no HA requirements, those VMs with local >> domain >> needs can be in their own DC, a local one? If it's just 5%, >> shouldn't be >> much of an effort? >> >> Can a host be in 2 datacenters? >> >> >> No, I suggested to dedicate a host (or several) with their own local DC >> for those 5%. >> Y. > > I have 5 hosts and dedicating 2 hosts for 5% seems a gigantic waste if you > ask me. > So I cannot do that. Not real solutions, but you might consider: Using nested-kvm and "virtual hosts" Copying the data to a local scratchpad upon every reboot, and perhaps rsync back to shared storage on shutdown.

Best, > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users

Mike, You can share and use your local storage via NFS. So all your storages are shared, and can be used in the same datacenter.

-----Original Message----- From: <users-bounces(a)ovirt.org&gt; on behalf of "Mike (maillinglists)" <maillist(a)probie.nl&gt; Date: Sunday 30 October 2016 at 13:02 To: &quot;users(a)ovirt.org&quot; <users(a)ovirt.org&gt; Subject: [ovirt-users] Local and Shared storage in same datacenter Hi guys, There have been a few related questions already that I could find, but I did not find anything relating to my specific use case. Currently it is not possible to mix local storage with shared storage in the same datacenter. The reason seems to be because of the storage pool manager (SPM). This is a role in the datacenter provided to one specific host. While I understand that this makes having local storage impossible, I believe there is a use case to have local storage in a shared storage datacenter. Consider the following: I have a few applications that require 1 milli second latency and at most 2 milli second. That is not consistenly achievable with shared storage, to that end I added flash storage to a few hypervisors. About 5% of my servers require this and are not that resource hungry to require a dedicated physical server. That same 5% also has no requirement to be migrated if a host fails. So in short I have 5 heavy hosts running ovirt with a shared storage domain on NFS for 95% of my servers. All running fine, but I am now unable to run my remaining 5%. To finish up my summary I have been testing various virtualization technologies, like VmWare and Hyper-V. They allow such configurations as I mentioned. I already had some chat on irc with various guys and they suggested that I put this on the mailing list, so here goes. My suggestion would be to evoluate from SPM to SDM. SDM stands for Storage Domain Manager. This would create the possibility to have all nodes in the datacenter participate in the storage handling. A extra benefit would be that local storage could be added. What do you think? Thanks for reading. Kind regards, Mike van Goor _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users

Mike, As workaround it's not very hard to create a mount command wrapper that converts local NFS mounts to bind-mounts. The propper way I think is to patch the VDSM service to handle local NFS mounts. In result, a NFS storage will work like a local storage if it's local.

-----Original Message----- From: Mike <maillist(a)probie.nl&gt; Date: Monday 31 October 2016 at 16:33 To: Pavel Gashev <Pax(a)acronis.com&gt;, &quot;users(a)ovirt.org&quot; <users(a)ovirt.org&gt; Subject: Re: [ovirt-users] Local and Shared storage in same datacenter Hi Pavel, Op 31-10-2016 om 11:22 schreef Pavel Gashev: > Mike, > > You can share and use your local storage via NFS. So all your storages are shared, and can be used in the same datacenter. I installed a nfs server on the hypervisor and am using it that way at the moment. It feels 'wrong' but it seems to work okay and it is fast as far as I can tell. Still would like to see another solution without the added latency of nfs and be able to utilize directio, etc. > > -----Original Message----- > From: <users-bounces(a)ovirt.org&gt; on behalf of "Mike (maillinglists)" <maillist(a)probie.nl&gt; > Date: Sunday 30 October 2016 at 13:02 > To: &quot;users(a)ovirt.org&quot; <users(a)ovirt.org&gt; > Subject: [ovirt-users] Local and Shared storage in same datacenter > > Hi guys, > > There have been a few related questions already that I could find, but I > did not find anything relating to my specific use case. > > Currently it is not possible to mix local storage with shared storage in > the same datacenter. > The reason seems to be because of the storage pool manager (SPM). > This is a role in the datacenter provided to one specific host. > > While I understand that this makes having local storage impossible, I > believe there is a use case to have local storage in a shared storage > datacenter. > Consider the following: > I have a few applications that require 1 milli second latency and at > most 2 milli second. > That is not consistenly achievable with shared storage, to that end I > added flash storage to a few hypervisors. > About 5% of my servers require this and are not that resource hungry to > require a dedicated physical server. > That same 5% also has no requirement to be migrated if a host fails. > > So in short I have 5 heavy hosts running ovirt with a shared storage > domain on NFS for 95% of my servers. > All running fine, but I am now unable to run my remaining 5%. > > To finish up my summary I have been testing various virtualization > technologies, like VmWare and Hyper-V. > They allow such configurations as I mentioned. > > I already had some chat on irc with various guys and they suggested that > I put this on the mailing list, so here goes. > > My suggestion would be to evoluate from SPM to SDM. > SDM stands for Storage Domain Manager. > This would create the possibility to have all nodes in the datacenter > participate in the storage handling. > A extra benefit would be that local storage could be added. > > What do you think? > > Thanks for reading. > > Kind regards, > Mike van Goor > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > > _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users