COSMOS Storage

This article describes some high level storage information about COSMOS servers and addresses some possible issues.

Infrastructure Overview

Differences between storage devices

The server sheet is the best resource for detailed information on all devices.

• cosmos-storage-1 [WesterDigital NAS box] – the historical backup resource for all VMs but one of its volume is failing (last updated 12/10/2022).
• cosmos-storage-2 [Dell PowerStore] – houses most virtual drives for databases.
• cosmos-storage-3 [Dell PowerEdge] needs OS and network connection (last updated 12/10/2022).

Server	Access
cosmos-storage-1	Bound to IP and exposed – PUBLICLY available to devices in UALR network
cosmos-storage-2	iSCSI LUN – individual storage volumes are PRIVATE to each server
cosmos-storage-3	Needs setup

Unlike cosmos-storage-1 that can be accessed from any file browser through its IP, the cosmos-storage-2 PowerStore has ISCSI LUNs bound to a particular server’s IP and iSCSI Qualified Name (IQN). This is done from the online dashboard referred to in the server sheet.

This is an issue because the LUNs are not accessible from within VMs, due to them being bounded to the server IQN. They could be setup to be accessible by all VMs needing backups, but it sounds like overhead, the cosmos-storage-1 solution is working well. cosmos-storage-3 should be setup in a way that exposes part of its storage in order to be visible by individual VMs.

Troubleshooting

VM(s) inaccessible

This is likely due to a reboot of the server where the VM(s) storage became missing. This is because CHAP authentication is required when a server is booted and uses a remote ISCSI LUN to store virtual hard drives, like cosmos-5. Meaning this is like the server started with its hard drives pulled out. We need to find a solution to automate ISCSI boot with CHAP secret.

To fix this, follow below instructions below. For visual instructions on how to attach a ISCSI volume, follow instructions here.

1. RDP into faulty server
2. Launch “iSCSI Initiator” program
3. Hit Refresh if Discovered targets is empty
   • If still empty, check Discovery tab and make sure target portals are populated
4. Select target (there may be two, one is for redundancy – just use the first)
5. Connect > Advanced > Enable CHAP log on > fill Target secret (see below)
6. Restart VMs (select VM(s) in HyperV and hit Start – I recommend restarting a few at a time. Starting them all at once can cause resource contention

cosmos-storage-2 (PowerStore) IP: 144.167.136.46
Single CHAP authentication credentials:
name: By default, the iSCSI initiator uses its IQN as CHAP user name. For cosmos-5, iqn.1991-05.com.microsoft:cosmos-5.ad.ualr.edu
cosmos-5 target secret: iRmlcIZMmhJpPuIh