Since I’m slinging around these large ~101gb k32 plot files all the time now, I find it handy to know exactly how long it’s gonna take to copy plots based on the megabytes per second of throughput I am seeing:
| copy speed | time | copy speed | time |
|---|---|---|---|
2000 MB/sec |
0:51 |
175 MB/sec |
9:50 |
1000 MB/sec |
1:43 |
160 MB/sec |
10:46 |
650 MB/sec |
2:39 |
150 MB/sec |
11:29 |
600 MB/sec |
2:52 |
140 MB/sec |
12:18 |
500 MB/sec |
3:26 |
130 MB/sec |
13:15 |
450 MB/sec |
3:49 |
111 MB/sec |
15:31 |
350 MB/sec |
4:55 |
50 MB/sec |
34:28 |
250 MB/sec |
6:53 |
33 MB/sec |
52:14 |
200 MB/sec |
8:37 |
10 MB/sec |
2:52:22 |
(I may make this into a graph later)
I bolded two;
- 111 MB/sec is typical gigabit ethernet throughput speeds for a wired network.
- 200 MB/sec is around the typical write speed I’ve seen from external single big 3.5" hard disks… but it can degrade so that’s a best case scenario. I often see it slip down to 175, 160, 150, 140, 130 as the drive fills or just… I don’t even know. But I’ve never seen a single large drive do better than 235MB/sec reads.
I was so out of touch with 3.5" HDD speeds since I’ve been an all-SSD guy for, gosh, almost a decade now. I’ve seen max 250mb/sec reads and max 235mb/sec writes with the larger drives.
USB speeds are also relevant and can be a bottleneck:
- If the port isn’t labeled, it’s probably standard USB and 5gbps.
- If the port says “SS” it is superspeed and 10gbps max.
- If you are really lucky, the port says “SS 20” and it is the latest & greatest 20gbps max.
so:
| port | speed | k32 101gb copy time |
|---|---|---|
| USB | 5 gpbs | 2:57 |
| USB SS | 10 gbps | 1:28 |
| USB SS 20 | 20gbps | 0:44 |
| Thunderbolt 3 | 40 gbps | 0:22 |
I have found it is very difficult to hit these speeds due to interface and controller overhead. In my experience you get more like 660mb/sec (3 min) writes on USB SS 20 / TB3 and 330mb/sec (5 min) writes on USB SS.
Anyway, the TL;DR is you’re doing great with traditional spinning disks if you are seeing 10 minutes k32 plot copy time or less.