Speeding Up an Initial Local Time Machine Backup
To assess the effect of IOPOL_THROTTLE policy, standardised TMA backups were run with and without the policy in force, on an M1 Pro MBP backing up to an external USB-C/SATA SSD under macOS 12.2.1.
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However, transfer rates during the backup itself showed that turning the policy off resulted in a huge increase in transfer rates[…]
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The big disadvantage of using kernel states to completely disable IOPOL_THROTTLE policy is that this can only be applied globally, which includes I/O for Spotlight indexing, and file synchronisation and other background tasks. While it could be used to great effect to accelerate a large first full backup, leaving the policy disabled in normal circumstances could readily lead to adverse side-effects, in which indexing threads swamp important user storage access.
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