Is it possible to have 2 Virtual Disks and then combine them in Proxmox? Or is there a better solution?

[farfy]

I'm looking at upgrading a few of my disks in my Dell R530. Currently, I have 3 x 2TB and then 5 x 4TB. I'll be upgrading 4 drives to 8TB. Currently, in Proxmox, I have 2 LVM Storage groups, 1 6TB, the other 18TB.

If I create 2 separate virtual disks on my Dell raid controller, is it possible in Proxmox to create a new LVM and group the 2 virtual disks as one big one? I'm very new to proxmox, so please be patient with my lack of knowledge!

Is there a better configuration I should be using?

Essentially, what I'm trying to accomplish is to utilize as much storage as I can for my media server (plex/arrs/etc) without having to work with 2 separate pools of storage, so any advice/info would be greatly appreciated!

 

[Kingneutron]

It's generally not advisable to span an LVM across separate physical disks unless they're running on top of a RAID - mirror or better. If a physical disk dies, you put the whole LVM at risk. Backups are your friend.

Since it sounds like you have space in the server, I would recommend looking into ZFS and run either a mirror pool (RAID10 equivalent) or a 6-disk RAIDZ2.

https://wintelguy.com/zfs-calc.pl

6x8TB RAIDZ2 with slop space and 5% free space limit would give you ~26.6TiB of usable free space before compression.

4x8TB mirror pool would give you ~13.34TiB of usable free space.

ZFS has the advantage of being easier to admin than LVM - you typically give zfs the entire disk (or a partition) and generally don't mess around with resizing unless you're migrating to larger disks.

 

[farfy]

so, would ZFS be better than LVM? Currently, the storage space is in RAID 5 on the Dell controller (2 separate virtual disks with the physical drives in RAID 5)

I don't care too much about redundancy, looking for whatever can give me the most usable storage space with the configuration. If you started from scratch, what would be your recommended setup of 4 x 8 TB drives plus 4 x 6 TB drives? If possible, I'd like in Proxmox for this to be one large pool instead of 2 completely separate pools

 

[Kingneutron]

> what would be your recommended setup of 4 x 8 TB drives plus 4 x 6 TB drives?

With different sized drives, my initial inclination is 2 different zfs pools, possibly with soft symlinks to link the directory structure.
If you went with 8x8TB drives I would do a single-vdev RAIDZ2.

However, with mirrors you can probably get away with making it all one big pool. Define the pool with the 6TB drives 1st. YMMV
(obviously use the correct short-drive identifiers like sdc)

zp=yourpoolnamehere
zpool create -o ashift=12 -o autoreplace=on -o autoexpand=on -O atime=off -O compression=lz4 $zp \
mirror 6tb1 6tb2 \
mirror 6tb3 6tb4 \
mirror 8tb1 8tb2 \
mirror 8tb3 8tb4

This will give you some leeway to replace the 6TBs down the road with 8TBs. As soon as you replace both disks in a column (one after the other and wait for resilver to finish first, not at the same time!), you should see the free space increase.

There are other ways of combining different sized disks like unRAID, but for the most part I don't mix disk sizes in my ZFS pool unless I replace a mirror column with 2x larger drives. Balanced I/O is kind of important.

IF you have good backups you might get away with a single striped-disk pool (no raidz or mirrors), but if 1 drive dies there goes the whole thing. You would also miss out on self-healing scrubs. Up to you to determine how long it would take to restore everything from backup vs having redundancy and just replacing a failed disk with very little hassle.