Bad performance on NFS share, SMB works fine

TrueNAS General
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Hi, I am running a new installation of TrueNAS Community Edition on my Proxmox host for testing purposes.

I already had problems with the speed of the NFS connection on my ‘old’ system (Core, on standalone hardware), so I have now installed the new system on a trial basis.

I have currently set up a pool of two hard drives. I have created two datasets on this pool. One for the NFS share and one for the SMB share.

When I connect via SMB and run a FIO test, I get a transfer rate of around 250 MB/s, which is fine. When I run the FIO test with the NFS share, I only get 7462 kB/s.

fio --name=write-test --size=1G --filename=fio-testfile --bs=128k --rw=write --direct=1 --numjobs=1 --time_based --runtime=30 --group_reporting

So far, I haven’t made any optimisations to TrueNAS. I just created users, created a pool, set up shares and then ran the tests.

What could be causing the problem with the NFS share?

2

Are you doing sync writes to the NFS share ?
The difference seems to be a bit too extreme, but try disabling sync writes in the options of the dataset.

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If i disable the sync, the performance is very good, around 250MB/s.

Currently i am lost about finding a valid solution. Does smb not sync data? What is the difference there between smb and nfs?

4

SMB is async NFS can be sync or async. If you don’t need your NFS client to sync writes then you can either disable sync on the dataset as @Farout has already said or tell your client not to mount sync.

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5

If your client needs sync you can add a slog (high write endurance low latency ssd with plp) to speed up sync writes

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Hi. Thank you very much for your answers, that explains the striking difference.

7

@LarsR discribed the technical solution if you NEED sync writes. If you dont know if you need it or not , chances are high you dont.

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8

IIRC, Time Machine backups desire sync over SMB. Ditto some database operations.

Presumably, the file system is smart enough to let most stuff transfer on a async basis and only uses sync transactions when it’s required by the SMB user (ie Time Machine)?