this post was submitted on 02 Nov 2023
29 points (93.9% liked)

Selfhosted

40183 readers
498 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 1 year ago
MODERATORS
 

I've posted a few days ago, asking how to setup my storage for Proxmox on my Lenovo M90q, which I since then settled. Or so I thought. The Lenovo has space for two NVME and one SATA SSD.

There seems to a general consensus, that you shouldn't use consumer SSDs (even NAS SSDs like WD Red) for ZFS, since there will be lots of writes which in turn will wear out the SSD fast.

Some conflicting information is out there with some saying it's fine and a few GB writes per day is okay and others warning of several TBs writes per day.

I plan on using Proxmox as a hypervisor for homelab use with one or two VMs runnning Docker, Nextcloud, Jellyfin, Arr-Stack, TubeArchivist, PiHole and such. All static data (files, videos, music) will not be stored on ZFS, just the VM images themselves.

I did some research and found a few SSDs with good write endurance (see table below) and settled on two WD Red SN700 2TB in a ZFS Mirror. Those drives have 2500TBW. For file storage, I'll just use a Samsung 870EVO with 4TB and 2400TBW.

SSD TB TBW
980 PRO 1TB 600 68
2TB 1200 128
SN 700 500GB 1000 48
1TB 2000 70
2TB 2500 141
870 EVO 2TB 1200 117
4TB 2400 216
SA 500 2TB 1300 137
4TB 2500 325

Is that good enough? Would you rather recommend enterprise grade SSDs? And if so, which ones would you recommend, that are m.2 NVME? Or should I just stick with ext4 as a file system, loosing data security and the ability for snapshots?

I'd love to hear your thought's about this, thanks!

you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 17 points 1 year ago (11 children)

ZFS doesn't eat your SSD endurance. If anything it is the best option since you can enable ZSTD compression for smaller reads/writes and reads will often come from the RAM-based ARC cache instead of your SSDs. ZFS is also practically allergic to rewriting data that already exists in the pool, so once something is written it should never cost a write again - especially if you're using OpenZFS 2.2 or above which has reflinking.

My guess is you were reading about SLOG devices, which do need heavier endurance as they replicate every write coming into your HDD array (every synchronous write, anyway). SLOG devices are only useful in HDD pools, and even then they're not a must-have.

IMO just throw in whatever is cheapest or has your desired performance. Modern SSD write endurance is way better than it used to be and even if you somehow use it all up after a decade, the money you save by buying a cheaper one will pay for the replacement.

I would also recommend using ZFS or BTRFS on the data drive, even without redundancy. These filesystems store checksums of all data so you know if anything has bitrot when you scrub it. XFS/Ext4/etc store your data but they have no idea if it's still good or not.

[–] [email protected] 3 points 1 year ago (10 children)

Thank you so much for this explanation. I am just a beginner, so those horror stories did scare me a bit. I also read, that you can fine tune ZFS to prevent write amplification so I'll read into that subject a bit more.

I thought ZFS without redundancy did give no benefits, but I most have gotten that wrong. Thanks again!

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago) (9 children)

ZFS without redundancy is not great in the sense that redundancy is ideal in all scenarios, but it's still a modern filesystem with a lot of good features, just like BTRFS. The main problem will be that it can detect data corruption but not heal it automatically. Transparent compression, snapshotting, data checksums, copy-on-write (power loss resiliency), and reflinking are modern features of both ZFS/BTRFS, and BTRFS additionally offers offline-deduplication, meaning you can deduplicate any data block that exists twice in your pool without incurring the massive resources that ZFS deduplication requires. ZFS is the more mature of the two, and I would use that if you've already got ZFS tooling set up on your machine.

Note that the TrueNAS forums spread a lot of FUD about ZFS, but ZFS without redundancy is ok. I would take anything alarmist from there with a grain of salt. BTRFS and ZFS both store 2 copies of all metadata by default, so bitrot will be auto-healed on a filesystem level when it's read or scrubbed.

Edit: As for write amplification, just use ashift=12 and don't worry too much about it.

[–] [email protected] 1 points 1 year ago (1 children)

I barely scratched the surface with ZFS, so I'm not going to touch another file system for a while now. I'm fine with detecting data corruption only, since those files (on the static data storage) can be replaced easily and hold no real value for me. All other data will be either on the redundant pool or is saved to several other media and even one off-site copy.

I already wrote down ashift=12 in my notes for when I set it up.

In general, I found there is a lot of FUD out there when it comes to data security. One I liked a lot was ECC RAM being mandatory for ZFS. Then one of the creators of it basically said: "Nah, it's not needed more than for any other file system'.

[–] [email protected] 2 points 1 year ago

Yeah ECC RAM is great in general but there's nothing about ZFS that likes ECC more than any other thing you do on your computer. You are not totally safe from bit flips unless every machine in the transaction has ECC RAM. Your workstation could flip a bit on a file as it's sending it to your ZFS pool, and your ECC'd ZFS pool will hold that bit flip as gospel.

load more comments (7 replies)
load more comments (7 replies)
load more comments (7 replies)