Earlier this year Synology sent me a DS923+ to review and test. Thanks again to Synology for making this possible, it is much appreciated. In part one of this series, I did the initially unpacking, set up, and getting the NAS ready. You can read part one here.
In this post I will focus on setting up LUNs, connecting it to my existing VMware Hosts and testing the snapshot function of the LUNs. Let’s get started…
In our last post we set up a storage pool and volume. I currently have only 2 hdds installed; given this is a 4 bay NAS I can still expand. Also this NAS currently has no SSD caching set up.
The capacity of the pool is 5.4TB, and we currently have 4.9TB free. Plenty of space for some VMs.
First thing, we need to navigate to SAN Manager>LUN and create a new LUN. It’s a pretty straight forward process, give it a name, location (since I only have 1 volume, this is where the LUN will reside on), and capacity. For space allocation, we need to choose thin provisioning to have all advanced features, like snapshots, available to us.
Next choose an iSCSI target and set permissions .
I already created an iSCSI target on the NAS before. You should do this before creating the LUN. Navigate to iSCSI>create.
In the next step you can map it to an existing LUN, create a new LUN, or map later. For this we will map it later.
There is one important step for using a LUN with VMware hosts; you want to make sure to allow multiple sessions from one or more initiators! Select the Target you just created and click on edit. Go to Advanced and put a check mark here:
Now our LUN is ready for use. While we are in the SAN Manager, let’s set up snapshots. Navigate to Snapshots in the SAN Manger, and select the LUN we just created. Under settings, set up a schedule. I like to run it daily at 2:00am, when there is not much load on the system. One of the newer features with DSM is to be able to create immutable snapshots. An immutable snapshot/backup is designed so it can’t be deleted before the protection period, not even by an administrator. This is one of the primary strategies to protect against ransomware. Synology did a good job on this, I wasn’t able to delete the snapshot folder or the snapshot. I did not test what would happen if you were to do a factory reset of the SAN. When I have more time I might try it. But this is another reason to have MFA set up.
Under Application, if you have the Synology Storage Console installed in your VMware environment (which I do), you can enable application consistent snapshots. I do recommend installing the console, it is very easy to do and gives you a nice overview directly from vCenter as well.
Here is a screenshot of the Console:
Ok, for now we are done on the Synology side. Let switch over to our host and connect it to our LUN. Navigate to Storage>iSCSI and add a static target. We need to use IQN we created on our Synology box, when we created an iSCSI target in the SAN Manager. Put that in and the ip of our NAS.
Do a re-scan after saving the configuration and go to Datastores>New Datastores. Create a new VMFS datastore and our newly provisioned LUN should show up there! Give it a name, format with VMFS 6 and we have our LUN now in vSphere.
For Snapshot testing, I’m going to move one of my VMs over to the new storage we created. For this, I’m using LibreNMS, a networking/system monitoring tool I use in my home lab.
The VM is running happily (for now). Let’s create a snapshot of the LUN in SAN Manger of our NAS.
Creating the snapshot took about 12 seconds only. Seems all good here.
Now lets break the VM, by deleting some files of it. Like so:
And they are gone. Don’t think this VM will start anymore….
…nope, won’t turn on.
Moment of truth! Let’s go back to the SAN Manager on Synology and restore the snapshot.
(For this test I did not disconnect the session). Normally I would disconnect. Restore took about 25 seconds, so let’s see if it powers on.
And voila, our VM is back and running! All files are back.
So it took us less than 30 seconds to restore a VM from a LUN snapshot. Pretty sweet. One thing to consider: in this case, we had one LUN for one VM. You could easily put several VMs on one LUN, but the snapshot is per LUN. If you roll back to a snapshot, you revert all workloads on that LUN back to the restore point. Alternatively, you could create individual LUNs per VM to avoid this.
This is just something to be aware when you start experimenting with LUN based snapshots.
In conclusion, this was pretty easy to set up and worked exactly as it should. I’m especially happy about the immutability function built-in.
I hope you found this post useful. Let’s see what we can get into the next time with this box!
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