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Tell me why I shouldn't use btrfs (lemmy.zip)

submitted 1 day ago by [email protected] to c/[email protected]

103 comments fedilink hide all child comments

About a year ago I switched to ZFS for Proxmox so that I wouldn't be running technology preview.

Btrfs gave me no issues for years and I even replaced a dying disk with no issues. I use raid 1 for my Proxmox machines. Anyway I moved to ZFS and it has been a less that ideal experience. The separate kernel modules mean that I can't downgrade the kernel plus the performance on my hardware is abysmal. I get only like 50-100mb/s vs the several hundred I would get with btrfs.

Any reason I shouldn't go back to btrfs? There seems to be a community fear of btrfs eating data or having unexplainable errors. That is sad to hear as btrfs has had lots of time to mature in the last 8 years. I would never have considered it 5-6 years ago but now it seems like a solid choice.

Anyone else pondering or using btrfs? It seems like a solid choice.

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

How much ram and what is the drive size?

I suspect this also could be an issue with SSDs. I have seen a lot a posts around describing similar performance on SSDs.

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

64 gb of ecc ram (48gb cache used by zfs) with 2tb drives (3 of them)

[–] [email protected] 0 points 1 day ago (1 children)

Yeah it sounds like I don't have enough ram.

[–] [email protected] 1 points 23 hours ago (1 children)

ZFS really likes RAM, so if you're running anything less than 16GB, that could be your issue.

[–] [email protected] 2 points 19 hours ago* (last edited 19 hours ago)

From the Proxmox documentation:

As a general rule of thumb, allocate at least 2 GiB Base + 1 GiB/TiB-Storage. For example, if you have a pool with 8 TiB of available storage space then you should use 10 GiB of memory for the ARC.

I changed the arc size on all my machines to 4GB and it runs a bit better. I am getting much better performance. I though I had changed it but I didn't regenerate initramfs so it didn't apply. I am still having issues with VM transfers locking up the cluster but that might be fixable by tweaking some settings.

16GB might be overkill or underkill depending on what you are doing.