All disks cache data to be written, which makes benchmarking them tricky. It has more serious consequences which macOS tries to allow for in file systems and backups.
SMB
Since Catalina, reports of Time Machine backups slowing to a crawl have become common, but the reasons are unclear. It’s time for Apple to inform us.
Have you got problems backing up to your NAS? Here is a series of four simple tests to perform to give clear insights and help you tune its performance.
Backing up using Time Machine over Gigabit Ethernet to another Mac providing shared backup storage in Monterey 12.1 delivered good performance of 35-43 MB/s.
A full Time Machine backup over SMB analysed in detail. This reveals that some of the measures reported in the log are likely to be inaccurate and misleading, and gives suggestions for improving performance.
Tackles decisions and problems, including whether to use APFS in the backup sparsebundle, AFP or SMB, and configuration.
Turning the data blocks into files and directories, these have common functions and additional features which can give rise to tricky problems.
With a new version of Xcode, I knew that my network backup would take several hours. Then, as it neared its conclusion, disaster struck: the router reset itself and the network share vanished.
Slow performance when backing up to a network share is mainly down to SMB. Without its improvement, Time Machine over a network is still dead in the water.
How can it take over 5 hours to back up 79 GB of files to a network share? That’s an average transfer rate of 4 MB/s, probably slower than your Internet connection.
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