Use ZFS dataset as storage directory?

[tycoonbob]

I'm not sure if I'm just overlooking something, or if I'm missing something completely.

I have a server (dual Xeon L5640s, 96GB RAM, 2x128GB SSD's in ZFS mirror for OS, 8x5TB drives in 2-way ZFS mirrors for data pool) in which I recently installed Proxmox VE 3.4 on. Install went great, got the boot volume in a ZFS mirror, created a new zpool with 4 vdev's each in 2-way mirror, and set up some shares. I plan to use this box for both centralized storage, as well as KVM host (Proxmox), and plan to create another zpool for VM's once I get a couple 500GB SSD's. In the mean time, I created a dataset/volume on my large ZFS zpool, in which I called "proxmox", set a quota of 200GB, and mounted at /tanks/tank_data_01/proxmox (my zpool is called tank_data_01, mounted at /tanks/tank_data_01).

I see the "proxmox" dataset, and I can successfully use it as a local directory with Proxmox, and I can create VM's and store ISO's on it. However, VM's won't start in this fashion (throws an error -- don't have that error handy). So I decided to add storage using "ZFS" from the drop down (as opposed to the "directory" I just tried with), and I can select my zpool. Problem is, I don't want to use the root of my pool for proxmox storage, and I want to use that proxmox dataset/volume. If I edit storage.cfg and append the correct path (/tanks/tank_data_01 to /tanks/tank_data_01/proxmox), it acts like it's working, but when I try to upload an ISO to that storage, it fails.

Is it not possible to select a ZFS dataset for my storage location, or do I have to use the root of my zpool? Any idea why I couldn't use the local path to that dataset? I know the error would be handy, and I'm trying to recall what it was. Server is offline at the moment and won't be back up until tomorrow.

Thanks!

 

[wolfgang]

Hi,
The error you got is because ZFS don't support O_DIRECT to solve this use at the VM Disk settings write back mode.
I do not understand why you can't select you tank_data_01 as an ZFSpool storage?
do you get a error msg?

 

[FastLaneJB]

Hi,
The error you got is because ZFS don't support O_DIRECT to solve this use at the VM Disk settings write back mode.
I do not understand why you can't select you tank_data_01 as an ZFSpool storage?
do you get a error msg?

Would it make sense for Proxmox to detect if a VM is on ZFS and if so change the default setting for a VM to one that does work? Also hide the setting which ZFS cannot support so people cannot pick it and have VM's that don't start.

Just a little GUI change to make life easier as the default is an option which doesn't work.

 

[tycoonbob]

Hi,
The error you got is because ZFS don't support O_DIRECT to solve this use at the VM Disk settings write back mode.
I do not understand why you can't select you tank_data_01 as an ZFSpool storage?
do you get a error msg?

root@proxmox01:~# zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
rpool                 18.9G  98.2G    96K  /rpool
rpool/ROOT            3.13G  98.2G    96K  /rpool/ROOT
rpool/ROOT/pve-1      3.13G  98.2G  3.13G  /
rpool/swap            15.8G   114G    64K  -
tank_data_01           256K  17.8T    19K  /tanks/tank_data_01
tank_data_01/audio      19K  17.8T    19K  /tanks/tank_data_01/audio
tank_data_01/proxmox    19K   200G    19K  /tanks/tank_data_01/proxmox
tank_data_01/users      19K  17.8T    19K  /tanks/tank_data_01/users
tank_data_01/video      19K  17.8T    19K  /tanks/tank_data_01/video

Basically, I want to use /tanks/tank_data_01/proxmox as storage for my VM/CT's. /tanks/tank_data_01/proxmox is a dataset/volume I created using:

zfs create tank_data_01/proxmox -o quota=200gb

If I try to add storage via the GUI, and select ZFS, it won't let me select that volume and instead only lets me select the pool "tank_data_01", which is not what I want to do.

If I try to add storage as a directory, and select that mount point (/tanks/tank_data_01/proxmox), it works until I try to boot a VM. That's when I get that O_DIRECT error, but thank you for that solution (which I haven't tested yet, but assume works).

Is it not possible to select a ZFS dataset/volume as the storage location when adding a ZFS type storage?