L2ARC and/or SLOG drives suggestion and advice on build

TrueNAS General
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Hi there, i would like to get some help from veterans here, i’m new to TrueNAS, i’m building a new instance (i already have the Proxmox hypervisor below), i would like to get some advice about the drives, would L2ARC and SLOG drives be a plus for me or i don’t really need it?

Proxmox VE
CPU: Xeon E5-2697A-V4 (16C/32T)
RAM: 4x 64GB DDR4 ECC RDIMM 2400MT/s
MOBO: Supermicro X10SRL-F FCLGA2011-3 C612
NIC: Intel X520-DA2 Dual SFP+ 10GBase-X
BOOT: 2x SSDs SATA 240GB Intel DC S3510 660 TBW (Mirror)
VMs: 2x SSDs NVMe 1TB Intel DC P4510 1.92 PBW (Mirror)
Dual 2.5" SATA SSD hot swap caddy for 3.5" bay
2x NVMe U.2 PCI-E adapters

TrueNAS Scale Build
CPU: Xeon E5-2630-V3 (8C/16T)
RAM: 8x 16GB DDR4 ECC RDIMM 2400MT/s
MOBO: Supermicro X10SRL-F FCLGA2011-3 C612
NIC: Intel X520-DA2 Dual SFP+ 10GBase-X
BOOT: 2x SSDs NVMe Intel Optane M10 64GB (Mirror)
VMs/Jails: 2x SSDs SATA 240GB Intel DC S3510 (Mirror)
DATA: 5x HDDs SATA WD HC310 4TB HUS726T4TALA600 (RAIDZ2, probably)
L2ARC/CACHE: ?
SLOG: ?
Dual 2.5 SATA SSD hot swap caddy for 3.5 bay
5x slot SATA/SASHDD hot swap caddy for 3x 5.25" bay

NAS use cases:

  • Personal general file storage and backup;
  • Torrent seeding (qBittorrent will be on Proxmox);
  • VM Backup from Proxmox;
  • Media server (Only files will be located in the NAS, the Plex and ARR stack will be on Proxmox)
  • Recursive VMs (For now, i can only think about Unbound DNS Server)
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  1. Unclear what you mean by “recursive VMs”. Please explain.

  2. There doesn’t seem to me to be anything wrong with your proposed configuration, and my further comments are at best minor tweaks.

  3. I would personally would have bought bigger Optanes (for your VMs/apps pool) and smaller SATA SSDs (as mirrored boot drive) because the apps and VMs will benefit most from Optane speeds.

  4. SLOG is only useful for synchronous writes i.e. for VMs and some apps, and it is only useful when A) SLOG is on a far faster technology than the actual data - so if your data is already on SSD (esp. Optane) this is unlikely; OR B) you have so much I/O to your SSD that it helps to split out the ZIL writes to a different SSD, or you want to spread the TBW between two drives. So in most cases, I would personally use fastest disks for synchronous writes and not complicate things with an SLOG.

  5. L2ARC: You have 128GB of memory (which is a heck of a lot even with a few small utility VMs), and I suspect that this (64GB+++ for ARC) is going to be way way more than you will ever need for ARC. For comparison I have a similar set of use cases (except for VMs), and my server has 10GB of memory i.e. 3GB of ARC and it performs brilliantly - my Plex metadata is on SSD, my Plex streaming benefits from ZFS pre-fetch, and I get a 99% ARC hit rate i.e. 99% of IOs are satisfied from memory. So whilst you certainly have enough memory to use L2ARC successfully, IMO it probably won’t give you much benefit.

  6. I appreciate the history of you coming from already having Proxmox - and the learned skills and invested time and effort - and Proxmox does provide additional functionality over and above TrueNAS virtualisation. But TrueNAS does provide virtualisation, and so you could keep things simple and migrate to a TrueNAS only environment on a single server - and perhaps use the other server as a NAS backup. But there is no definitive answer here - it depends on your needs and priorities, so I just wanted to mention this so you could consider it (if you haven’t already done so).

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  1. So, in fact, there won’t be recursive VMs, when a service is necessary and compatible with recursion, such as DNS Unbound servers, I confess that I was hasty in saying this;
  2. Noice
  3. I didn’t bought any of the drives, i just have the HDDs for now, that’s why i’m asking for advices lol
  4. Okay, no SLOG then, i don’t want to complicate things
  5. What would you recommend? Runnin only a single optane for metadata only?
  6. I think i’ll stay with Proxmox for a while, at least untill i get a lil bit more familiar with TrueNAS Scale

Which modifications would you do to my build to follow the best practices?

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  1. You probably don’t need L2ARC and you absolutely must use a mirror if you are going to have a metadata special vDev. What I am saying is that you need nothing for caching other than enough normal memory for standard ARC - and 128GB should easily be more than enough for your use cases.