Verification results show that macOS writing speed becomes unstable and slow when copying files over the network – Livedoor News

Verification results show that the writing speed of macOS becomes unstable and slow when copying files over the network

Network File System (NFS) is a system that allows files to be processed from different terminals by mounting a file system on a computer's storage volume over a network. YouTuber and engineer Jeff Giering reported an issue where file write speeds are somewhat slow when using NFS on macOS.

macOS Finder is still bad at copying network files Jeff Girling

https://www.jeffgeerling.com/blog/2024/macos-finder-still-bad-network-file-copies

Giering was testing a small NAS with a Raspberry Pi, but even with the speed of the Raspberry Pi's internal storage and over 800MB/s of PCIe-based storage, macOS couldn't get it across the network via NFS or Samba. When writing files, he was frustrated because the speed could not exceed 100MB/s.

For NFS, the write speed was around 82MB/s.

Samba's speed could reach 115MB/s, but it was very unstable, and the average write speed was about 70MB/s.

Mr. Gehring said he tried to fix the issue by changing settings or using tools, but was unable to locate the bottleneck on the macOS side. So Gering ran some tests.

First, I checked the network connection with iperf3, which can measure the network bandwidth, and found that the line speed of the 1Gbps connection was 940Mbps, and the line speed of the 2.5Gbps connection was about 2Gbps.

Next, we tested with IOzone, which checks disk I/O, and confirmed that it was possible to write a 1Mpc/50GB test file at 800MB/s to four SDDs (SATA connections) configured with Raidz1.

macOS Sonoma did not have a “/etc/nsmb.conf” file by default, but in past macOS, adding “signing_required=no” to this file disabled Samba package signing and improved speed, and it is said that it can improve. Gering was forced to disable signatures, but the problem of slow write speed persisted.

I used cp and rsync to see if this problem was specific to Finder. Then, the write speed for sharing was stable in both cases, but became slower overall.

Next, I started Transmit, an SFTP client, and used the scp command to copy the directory, and it copied at a steady speed of 112MB/s.

So, Mr. Gehring ran a similar test on a Windows 11 PC. As a result, I found the write speed to be around 100Mbps with a 1Gbps connection and 150Mbps with a 2.5Gbps connection. Additionally, loading speed was the same on macOS and Windows.

Testing has shown that Windows delivers faster and more consistent write speeds to network shares than macOS. According to Mr. Gehring, there was no indication of throttling even when monitoring using an activity monitor or htop. Giering reported that macOS doesn't have tools like Linux that can monitor interrupts and other resources, so it's impossible to resolve bottlenecks on the macOS side.

“I think we should be happy just because network sharing is working,” Gering commented.