On Sat, Aug 20, 2022 at 3:15 PM Dale <rdalek1...@gmail.com> wrote: > > Related question. Does encryption slow the read/write speeds of a drive > down a fair amount? This new 10TB drive is maxing out at about > 49.51MB/s or so.
Encryption won't impact the write speeds themselves of course, but it could introduce a CPU bottleneck. If you don't have any cores pegged at 100% though I'd say this isn't happening. On x86 encrypting a hard drive shouldn't be a problem. I have seen it become a bottleneck on something like a Pi4 if the encryption isn't directly supported in hardware by the CPU. 50MB/s is reasonable if you have an IOPS-limited workload. It is of course a bit low for something that is bandwidth-limited. If you want to test that I'm not sure rsync is a great way to go. I'd pause that (ctrl-z is fine), then verify that all disk IO goes to zero (might take 30s to clear out the cache). Then I'd use "time dd bs=1M count=20000 if=/dev/zero of=/path/to/drive/test" to measure how long it takes to create a 20GB file. Oh, this assumes you're not using a filesystem that can detect all-zeros and compress or make the file sparse. If you get crazy-fast results then I'd do a test like copying a single large file with cp and timing that. Make sure your disk has no IO before testing. If you have two processes accessing at once then you're going to get a huge drop in performance on a spinning disk. That includes one writing process and one reading one, unless the reads all hit the cache. -- Rich
