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iSCSI Targets in HA Used By OS X Desktops Directly

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iSCSI Targets in HA Used By OS X Desktops Directly

Postby Ciscogeek » Wed Oct 05, 2016 8:45 pm

Hello,

I've not been able to find a solution or anything even comparable to a deployment like we have and plan to change to. So maybe I can get something working here.

Currently, we're running SW iSCSI San (the old free iSCSI product) on a single server. On said server we create 1-15TB disk images from local storage that we mount directly on Mac OS X machines via GlobalSAN iSCSI initiators, and iSANmp as a user/permission mount manager. It works swimmingly for the studio.

But now we're changing things up we bought another server that we intended to run HA on (after rebuilding both) via the SW software, none of this virtualized infrastructure stuff. Just the same setup, but redundant to the point that we can fully lose a server and still be editing away as if nothing happened.

Currently I've labbed the setup with two Win 2012 servers, both with SW trial installed, 2 relevant interfaces, one for the 'SAN' network that our desktops connect through, and an 'HA' interface that is directly connected via the two servers for replication.

I've created per the instructions available (which are out of date; not matching the current product by the way), an image, which was then set for synchronous replication to the other host. It works without issues, I can see the replication traffic work.

When I go to mount the disk on the desktop, I add both IQN LUNs, from each host, and connect. Then mount the disk in iSANmp. 2 disk show up, but r/w states are mirrored on them and I can only mount one at a time. This makes sense as it's the same disk.

My HA test consists pretty much of the worst case scenario: I just kill the power to the host.... Nothing. It stalls and drops off. No failover. The other host complains about losing connection, and nothing moves on. This somewhat makes sense, as from my understanding of HA, you would need to connect to a virtual HA interface that's generated and shared by the two hosts running the HA service, so when the primary dies, the secondary/etc can take over. In this case, a virtual IP, and a virtual shared IQN/LUN that's neither the hostname of the first or second would be needed - At least that's what I see from a troubleshooting standpoint. Yet SW makes no such information available and the software does not have anything that indicates such a shared setup. Currently, each copy of the sync'd volume uses the IQN/LUN local to each host, making it impossible to add multiple hosts since the target is not the same.

Is this just something that cannot be done with SW? The setup seems pretty ripe to work for HA, if it can be bound correctly. Getting this working will dictate whether or not we buy a SW license. If we can't get this running in our setup, then it's off to another product/solution.

Thanks!
Ciscogeek
 
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Re: iSCSI Targets in HA Used By OS X Desktops Directly

Postby anton (staff) » Thu Oct 06, 2016 12:27 pm

Its not something could be done with anything on Earth or in this Universe actually...

viewtopic.php?f=5&t=1392

Either you run clustered file system (I'm not sure one existing on Mac but you might use Google for that) or you run metadata mgr like one Tiger Technologies does (they are compatible with our products). And... No, you can't do it with HDFS on its own.

Ciscogeek wrote:Hello,

I've not been able to find a solution or anything even comparable to a deployment like we have and plan to change to. So maybe I can get something working here.

Currently, we're running SW iSCSI San (the old free iSCSI product) on a single server. On said server we create 1-15TB disk images from local storage that we mount directly on Mac OS X machines via GlobalSAN iSCSI initiators, and iSANmp as a user/permission mount manager. It works swimmingly for the studio.

But now we're changing things up we bought another server that we intended to run HA on (after rebuilding both) via the SW software, none of this virtualized infrastructure stuff. Just the same setup, but redundant to the point that we can fully lose a server and still be editing away as if nothing happened.

Currently I've labbed the setup with two Win 2012 servers, both with SW trial installed, 2 relevant interfaces, one for the 'SAN' network that our desktops connect through, and an 'HA' interface that is directly connected via the two servers for replication.

I've created per the instructions available (which are out of date; not matching the current product by the way), an image, which was then set for synchronous replication to the other host. It works without issues, I can see the replication traffic work.

When I go to mount the disk on the desktop, I add both IQN LUNs, from each host, and connect. Then mount the disk in iSANmp. 2 disk show up, but r/w states are mirrored on them and I can only mount one at a time. This makes sense as it's the same disk.

My HA test consists pretty much of the worst case scenario: I just kill the power to the host.... Nothing. It stalls and drops off. No failover. The other host complains about losing connection, and nothing moves on. This somewhat makes sense, as from my understanding of HA, you would need to connect to a virtual HA interface that's generated and shared by the two hosts running the HA service, so when the primary dies, the secondary/etc can take over. In this case, a virtual IP, and a virtual shared IQN/LUN that's neither the hostname of the first or second would be needed - At least that's what I see from a troubleshooting standpoint. Yet SW makes no such information available and the software does not have anything that indicates such a shared setup. Currently, each copy of the sync'd volume uses the IQN/LUN local to each host, making it impossible to add multiple hosts since the target is not the same.

Is this just something that cannot be done with SW? The setup seems pretty ripe to work for HA, if it can be bound correctly. Getting this working will dictate whether or not we buy a SW license. If we can't get this running in our setup, then it's off to another product/solution.

Thanks!
Regards,
Anton Kolomyeytsev

Chief Technology Officer & Chief Architect, StarWind Software

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