Noob question: iSCSI zvol to ESXi, should files be visible to FreeNAS?

[nathanbuck]

Hi everyone,
Long time lurker, first time poster.

TL;DR - should FreeNAS be able to see anything stored on a zvol, or even the zvol itself (outside of management/config)?

I've come across a potentially interesting scenario with my FreeNAS > ESXi iSCSI setup, and I'm curious if anyone can shed some light.

On Blaise I have 2 pools, each has a single zvol (about 80% size allocation), which is shared via iSCSI (point-to-point ethernet, static IP) to Albert.
- The smaller faster pool/zvol contains VM configs and boot vmdks
- The larger slower pool/zvol contains the 'Capacity' vmdks for a couple of VMs (Apple Photos libraries etc)

FreeNAS can see some of the folders, vmdks etc on the smaller pool, but can't see anything on the 'Capacity' pool.
Running du -sh /* it shows a smaller usage than I expect too. My assumption is that FreeNAS wouldn't be able to see any files, as it's passing a block device straight to ESXi.

Really I'm just looking for a confirmation that the files I can see are heldover from the previous NFS setup (which at some point I rsync'd to the zvol), and not actually used by ESXi.

Thanks!

--- Background hardware info below here ---

** "Albert" ESXI 6.7u3 free licence **
Dell Poweredge T620- 2x Intel Xeon E5-2670, 64GB DDR3 ECC RAM
Pool1: LSI SAS2008 HBA to 10x Dell 4TB 7200rpm SAS disks
Onboard 2x Intel I350 GbE (link-aggregated to switch)
PCIe 2x Broadcom BCM5720 GbE (1 connected directly to Blaise/FreeNAS)

** "Blaise" FREENAS 11.3-RC1 **
Dell Poweredge R320- Intel Xeon E5-1410v2, 32GB DDR3 ECC RAM
Pool1: Dell H310 mini (flashed to SAS2008) to 4x Dell 600GB 15000rpm SAS disks
Pool2: LSI SAS2008 HBA to 8x Dell 2TB SAS disks
Onboard 2x Broadcom GbE (1 management LAN, 1 connected directly to Albert/ESXi)

 

[nathanbuck]

Below is the du outputs from each system. This seems to support the fact that it's looking at two completely different filesystems.

[nbadmin@albert:/vmfs/volumes/5de915de-0799d79c-3361-f01fafef4b22] du -sh *
128.0K ApplianceImages
31.3G ISOs
397.1G VirtualMachines

nbadmin@blaise[/mnt]# du -sh */*
1.7G SAS-15k-Z2-Pool/BlaiseTestVM(FreeNAS11.2)
3.6G SAS-15k-Z2-Pool/Carl(UnifiAppliance)
2.2G SAS-15k-Z2-Pool/Dmitry(DNS)
2.2G SAS-15k-Z2-Pool/Enrico(LetsEncryptACME)
32G SAS-15k-Z2-Pool/ISOs
18G SAS-15k-Z2-Pool/Klaus(Kali2019.3)
10G SAS-15k-Z2-Pool/Louis(Win10)
580M SAS-15k-Z2-Pool/Percy(pfSense)

 

[sretalla]

A zvol is block storage, so nothing is "visible" to FreeNAS in that it won't mount a filesystem... you can dd the bits from the block storage, so in theory, you can see it if you're determined to do that, but it's not going to be easy.

 

[HoneyBadger]

ZVOLs are not visible at all under /mnt, they are visible in /dev/zvol - what you are seeing is your old NFS data.

 

[nathanbuck]

Awesome, thanks for the confirmation. :)
I'll blitz this so I don't get confused again.

This is the fun of test systems, I suppose!