ESX6 can't communicate with ISCSI lun on DS1815+

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coop777
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ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Mon Jan 11, 2016 4:43 pm

Good morning all,

Last fall, I set up and VMware 6 ESXi host, installed VSphere on a Windows 10 machine, configured ISCSI storage and Target on my DS1815+ for storing virtual machines and followed tutorials on setting up an ISCSI adapter storage on the ESX host to access NAS storage. All went as expected and I have currently one VM configured on the NAS. I had not fired it up in awhile and noticed over the weekend that the ESX host has lost communication to the NAS. I see iscsi initiator errors failing to communicate to the NAS on the ESXi host, and have noticed in troubleshooting that the ESXi host (logged via SSH putty session) can neither ping nor vmkping the NAS. The ESXi host can ping other machines on my network, other machines can ping the ESXi host.

Troubleshooting steps taken in order:
Reboot ESXi Host
uninstall/reinstall/reconfigure ISCSI adapter on the ESXi host

configure VMKernel with static IP on ESXi host and bind to iscsi adapter (nowhere in tutorials did I see this as a step, but some of what I've read says the ESXi host HAS to have a VMKernel bound to the adapter for it to properly see the LUN storage)

Rebuild ESXi host
Uninstall Reinstall Vsphere
Create a secondary iscsi storage and target (also not detectable by ESXi host)
disabling/renabling CHAP on current storage
enable checkbox from one or more iscsi initiators in iscsi target configuration
Rebooting NAS

Thus far nothing has worked. Logs on the ds1815+ unfortunately do not seem to track any iscsi traffic so I'm not sure how to proceed further. Any input/response appreciated
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby Pentangle » Wed Jan 13, 2016 6:22 pm

First thing i'd check is the ping issue. if you can't ping between each device then you're unlikely to be able to go much further.

Also check out whether the ESXi box has had a problem with it's inbuilt firewall - i've seen some refuse connections to mundane things sometimes, although in every time i've seen a reboot of the ESXi box fix things.

Finally, ensure you've physically removed the power from both devices rather than relying on soft reboots, just in case :)
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Wed Jan 13, 2016 8:23 pm

Thanks for the reply Pentagle

I have physically cycled power for both boxes unplugging too. I did (via command line) turn off the ESXI firewall Monday evening temporarily - I will try that again to be sure. It is the lack of ping that bothers me, and yes without a ping I am dead in the water.

Does anyone know how to initiate a ping request directly from the NAS to a another device?

I did forget to put in the initial post of this thread that all of the rest of the NAS functionality is working normally. It is simply the iscsi connectivity that is not.
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Wed Jan 13, 2016 8:26 pm

The only other thing that may be an issue - two additional unmanaged Netgear GS108 switches are part of my home network directly connecting between the ESXI host and NAS. Prior to a physical move I had only one switch in place between the NAS, host, and router. It may be possible that the introduced switches did something, I need to test it again with how I know it was working. This (to me) seems a long shot - however I can't rule anything out at this time.
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby Pentangle » Thu Jan 14, 2016 8:27 pm

Apparently (although i've yet to try it myself), you can SSH into the Synology, so you should be able to Ping/Traceroute/etc when there.
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Sun Jan 17, 2016 4:11 pm

The plot thickens - a secondary host can also not ping the NAS and I have eliminated switches or cabling as a potential cause. I did ssh into the NAS and CAN successfully ping the esxi host from it. All signs seem to point to a setting somewhere on the NAS.

Anyone have any other ideas? I'll try opening a support case tomorrow....
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby Pentangle » Tue Jan 19, 2016 9:15 pm

If you can post the IP address settings (mask, gateway, etc) on both hosts and the Synology, then we'll start from there.
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Fri Jan 22, 2016 3:43 pm

This is a single subnet - 10.24.116.x
subnet 255.255.255.0
Gateway (router) IP 10.24.116.1

NAS IP is 10.24.116.10 (fixed IP)
ESXI server IP is 10.24.116.2 (fixed IP)
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Thu Feb 04, 2016 9:50 pm

Finally opened up a support case - I will keep the thread updated.
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Re: ESX6 can't communicate with ISCSI lun on DS1815+

Postby coop777 » Wed Nov 23, 2016 6:13 pm

My problem is SOLVED!!!!!

To anyone that experiences this - It was my Netgear unmanaged switches! I just last week purchased (2) managed l3 Cisco switches so that I could set up link aggregation on the DS1815+. I got everything swapped out and this morning, on a whim I logged into Vsphere, attempted a rescan of the iscsi adapter and BAM - login error! (I had changed the chap settings a few times). VM environment restored and I'm back in business!!!!

Now - what is REALLY perplexing me is why would an unmanaged switch stop a ping!?????

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