Setup help for a TrueNas noob please

[fsociety3765]

Hi all,

New to the forum.

I have a TrueNas server that I am setting up currently. I'm new to TrueNas so learning as I go.

My setup will consist of 4x 16TB SAS drives in a RAIDZ2 pool and 8x 6TB SATA drives in another RAIDZ2 pool. I also have 2x 1TB SATA SSD's which I plan to partition and use for L2ARC and SLOG for both pools.

My first question is about RAM. My understanding is that the general rule of thumb is 1GB RAM for every TB of storage. Is that the total storage or usable storage amount?

4x 16TB in RAIDZ2 - Total Storage 64TB - Usable Storage 32TB
8x 6TB in RAIDZ2 - Total Storage 48TB - Usable Storage 36TB

Would I need 112GB RAM or 68GB RAM for the ZFS pools?

I currently have just 16GB RAM allocated to the OS. Is this a sufficient amount for the OS?

I then have the 2x SSD's which I want to use as L2ARC and SLOG. I want to partition each drive with four partitions which would consist of a stripe of L2ARC for each pool and then a mirror of SLOG for each pool. I actually wanted to do this part on the command line but I haven't used FreeBSD much before. How do I list the available drives? The "lsblk" command doesn't work currently. I think I can install but the OS won't let me at the moment.

Any advice and assistance would be greatly appreciated.

Thanks,

FS

 

[sretalla]

How do I list the available drives? The "lsblk" command doesn't work currently. I think I can install but the OS won't let me at the moment.

You don't use pkg on the host.

You can use camcontrol devlist as a starting point at the CLI, but perhaps you should start with the GUI? Storage | Disks.

 

[sretalla]

My first question is about RAM. My understanding is that the general rule of thumb is 1GB RAM for every TB of storage. Is that the total storage or usable storage amount?

4x 16TB in RAIDZ2 - Total Storage 64TB - Usable Storage 32TB
8x 6TB in RAIDZ2 - Total Storage 48TB - Usable Storage 36TB

Would I need 112GB RAM or 68GB RAM for the ZFS pools?

I currently have just 16GB RAM allocated to the OS. Is this a sufficient amount for the OS?

For the OS, 8GB is the right amount (and the stated minimum).

If you want any kind of reasonable performance from ZFS (and it seems you do if you think you want SLOG and L2ARC), ADD much more RAM.

The RAM recommendation holds for pools of smaller sizes, but becomes just a very rough indication as disk sizes are growing now.

You need to look at your intended use of the pool(s) and performance requirements (particularly IOPS if you want to do block storage for VMs or iSCSI/NFS). (read this: https://www.truenas.com/community/threads/the-path-to-success-for-block-storage.81165/)

 

[fsociety3765]

The main use case is multimedia storage. But also Time Machine backups, backups of VM images. I also plan to self-host Nextcloud so it will be used for that too at some point. But the main thing is multimedia storage to point a Plex server to.

The 4x 16TB SAS drives are brand new and unused thus far. The 8x 6TB are being re-used from my previous setup with a Qnap 8-bay NAS which failed and could not be repaired. I have erased and tested each one before re-using them.

How much RAM are we talking? I currently have a total of 256GB RAM in Proxmox (TrueNas running as a VM), but I need a fair bit for the Plex server as I plan to do RAM transcoding, plus I have other plans for other VM's that will need RAM too. I can get more RAM of course but was hoping 256GB would be enough to get me going.

If I were to allocated 128GB RAM to TrueNas for now, is there a way to know that more RAM is needed so I can scale it up accordingly? Will the OS tell me it's low on RAM or will I just see poor performance?

 

[Samuel Tai]

Do you need realtime transcoding, or can you live with batch transcoding after-hours? How many simultaneous Plex viewers and transcoding sessions do you anticipate?

For me, my system maxes out at 16 GB, but I'm the only viewer. Setting Plex to auto-transcode to 20 Mbps works for me, as I'll only view from either my iPad or my desktop via Chrome browser. If you have a larger household, and need to support 5 or more viewing/transcoding sessions simultaneously, you'll want to start at 64 GB.

If you can't go that high, you could also supplement with L2ARC. There's differences of opinion here on whether L2ARC is useful below 128 GB, but even at my 16 GB, I see a speedup with L2ARC vs without.

 

[ChrisRJ]

@fsociety3765 , running TrueNAS in a VM requires special considerations and care due to the direct access to the hard disks ZFS needs. Please search the forums, if you haven't already done so ;-)

 

[fsociety3765]

@fsociety3765 , running TrueNAS in a VM requires special considerations and care due to the direct access to the hard disks ZFS needs. Please search the forums, if you haven't already done so ;-)

I’m all good on that front thanks.

I have my SAS HBA passed directly through to the TrueNAS VM, as well as the two individual SSD’s passed directly through so TrueNAS has complete control over them.

All the drives show up in the drives section of the GUI.

Is there a way to partition drives from the GUI? I'm not in front of it at the moment. I need to partition the SSD’s for the L2ARC stripes and SLOG mirrors.