ZFS on top of any hardware RAID is not supported

[rajasekhar]

Dear Team,
I have brand new HP server and we have Smart Array P420i with 2 GB FBWC cache hardware Raid controller. As per the document "https://pve.proxmox.com/pve-docs/pve-admin-guide.pdf", As ZFS offers several software RAID levels, this is an option for systems that don’t have a hardware RAID controller. I am confused here, whether I can use ZFS or I have to proceed with XFS.

I am very interested to use "Proxmox", so I choose this product for Virtualization and Backup solution.

My Raid level is 1+0 and with the Smart Array P420i with 2 GB FBWC cache hardware Raid controller.

Please suggest me on this which filesystem to be used?

 

[aaron]

If you want to use ZFS (and I recommend it as it has many nice features) you should switch the RAID controller to a real HBA controller. If you want to use the RAID controller (P420i) you should either select ext4 or xfs as root file system during the installation.

The reason is that ZFS is not just a file system but also RAID and volume manager. It wants access to the disks as raw as possible. Therefore, either HBA or direct SATA controllers. HW RAID controllers interfere too much by doing some caching themselves or omitting certain data of the disk to the OSD, such as model and serial number or SMART values.

 

[rajasekhar]

Hi Aaron,
I am really impressive for your quick reply. It is really appreciated.
My next question is , If I choose the root filesystem as "xfs" then can I use this for vmsnapshots and vmbackups ?
(Because I have to perform the VMbackups weekly and monthly, That is the reason i choose proxmox)

 

[aaron]

If you use a FS other than ZFS during installation, the installer will set up an LVM on the root disk. One volume will be used for the root FS and another LV will be a thin pool used to store guest disks as volumes.

Backups of VMs don't need snapshotting on the storage level (for containers it does matter, see [0]).

Since the default pool used in that case is a thin LVM, it does support snapshots [1].

[0] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_backup_modes
[1] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_storage_types