Backup speed

last modified

2023–9–5

Drive and port

External drive plugged into left front port:
Bus 003 Device 002: ID 152d:0567 JMicron Technology Corp. / JMicron USA Technology Corp. JMS567 SATA 6Gb/s bridge
6 Gbit/s SATA drive in enclosure, connected via USB 3.0.

So the drive seems to be at a matching USB port, since we don’t have better than 3.0.

Transfer speed

USB 3.0 SuperSpeed is 5 Gbit/s, corresponds to data transfer at 500 MB/s after encoding overhead.

Mount options

/dev/sdc1 on /media/Extern type ext4 (rw,nosuid,nodev,noexec,relatime,stripe=8191,user)

seem to be optimal.

Many small files

Copying copy: 60 folders, 1035 files, 39819.023312 MB

~/Store$ time cp -pr copy /media/Extern/ ; time sync

real    6m0.124s
user    0m0.603s
sys     1m1.452s

real    0m9.960s
user    0m0.001s
sys     0m0.001s

39819 MB in 370 s → 107.6 MB/s

One big file

/media/Extern$ time dd if=/dev/zero of=whatever bs=1M conv=fdatasync count=6000
6000+0 records in
6000+0 records out
6291456000 bytes (6.3 GB, 5.9 GiB) copied, 53.5747 s, 117 MB/s

real    0m53.866s
user    0m0.000s
sys     0m4.016s

6291.5 MB in 54 s → 116.8 MB/s

With sync option

Copying martha: 2 files, 139.675482 MB

~/Store/copy$ time cp -pr martha /media/Extern/ ; time sync

real    2m11.311s
user    0m0.013s
sys     0m1.197s

real    0m0.325s
user    0m0.002s
sys     0m0.000s

139.7 MB in 132 s → 1.058 MB/s

Much slower!