Tag Archive for devices

Cannot See Any iSCSI Devices on Synology from a vSphere Host

Just a quick fix I discovered this weekend. It’s probably quite specific but hopefully if you come across this in future it will save you some time.

I had just finished rebuilding the second node in my lab from 5.1 with a fresh install. I added the software iSCSI initiator and connected it to my iSCSI target (Synology DS412+) using Dynamic Discovery. I then rescanned for a list of devices, and although I was picking up the IQN for the iSCSI server, I couldn’t see any devices!

I tried lots of things including removing and re-adding the initiator, messing with iSCSI bindings, but nothing! Very frustrating.

After a bit of googlage, I came across this KB article from VMware:

Cannot see some or all storage devices in VMware vCenter Server or VirtualCenter (1016222)

Although this was specific to VI3/vSphere 4, it did trigger a thought! Just before I built the new node, I rejigged all of my storage LUNs, deleting 3 old ones in the process (which just so happened to be the first 3 LUNs on my NAS). What I believe this caused is that the LUNs were viewed by node 1 as different LUN IDs on node 2, so they refused to show up!

So now, the fix. Incredibly simple as it turns out:

  1. Created three new temp 10GB LUNs on my old NAS which would then assume LUN IDs 1/2/3 as they originally had (before I deleted them).
  2. Rescan the new node of the cluster for storage
  3. Confirmed all of the LUNs are now visible
  4. Deleted the three temp LUNs from the Synology (I don’t plan to add any more nodes for now so I have no need of these temp LUNs, but as they’re thin provisioned anyway it actually wouldn’t hurt to leave them there).
  5. Rescan the ESXi host again to ensure it can still see the LUNs.
  6. Job done!

Synology iSCSI Devices

Not much to it, but worth a quick post I thought as this simple issue wasted a chunk of my time!

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