I need to exposs an iscsi disk to be used as a main disk in a vm. Because I am pretty new in this solution I would like to ask some tips and good practices to avoid making rookie mistakes that can really hit the performance or availability.
What are the common things I should take into account before deploying everything?
More like, if you wanted the storage under the LUN to be shared through the VM. Essentially, mount the LUN into the VM and then run NFS/SMB from the VM as a NAS. Works out pretty well since with a little bit of trickery you can have a NAS that is also HA (assuming the storage pool doesn’t go down).
Since we don’t know what server or VM tech you’re using the advice will be pretty generic. For self hosting, you can likely get away with your ISCSI traffic sharing the LAN interface with your usual vm traffic but if you need high throughput you will want ISCSI optimized nics and turn on jumbo frames (mtu of 9000 is the standard here). This requires a switch that supports jumbo frames as well.
For Windows, I find the ISCSI support to be very lacking. Every time I have used it I have had sporadic loss of connectivity, failure to mount on boot, and other issues. I would avoid it.
For ESXi you can map an ISCSI lun as a datastore and create vmdks on top. This functions the same if you use actual FC luns or NFS mounts, and have had no issues with reliability. There’s also RDM which is raw direct map which can mount the ISCSI lun as a disk of the vm. If you’re using vSphere I would advise against this as you lose the ability to vMotion or use DRS.
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Is there a specific reason to mount the lun directly opposed to creating a virtual disk? Performance, maybe?
More like, if you wanted the storage under the LUN to be shared through the VM. Essentially, mount the LUN into the VM and then run NFS/SMB from the VM as a NAS. Works out pretty well since with a little bit of trickery you can have a NAS that is also HA (assuming the storage pool doesn’t go down).
With that said, I’m very interested too.
Unless I completely misunderstood your question
Since we don’t know what server or VM tech you’re using the advice will be pretty generic. For self hosting, you can likely get away with your ISCSI traffic sharing the LAN interface with your usual vm traffic but if you need high throughput you will want ISCSI optimized nics and turn on jumbo frames (mtu of 9000 is the standard here). This requires a switch that supports jumbo frames as well.
For Windows, I find the ISCSI support to be very lacking. Every time I have used it I have had sporadic loss of connectivity, failure to mount on boot, and other issues. I would avoid it.
For ESXi you can map an ISCSI lun as a datastore and create vmdks on top. This functions the same if you use actual FC luns or NFS mounts, and have had no issues with reliability. There’s also RDM which is raw direct map which can mount the ISCSI lun as a disk of the vm. If you’re using vSphere I would advise against this as you lose the ability to vMotion or use DRS.
Thanks for the comment, I will try to check but performance should not be an issue. In the end it is personal selfhosted service.