Is 30 MBps (30 megabytes/sec) an acceptable data transfer speed for SATA III to SATA II copy?
I'm copying data off one HDD into another. Both HDDs are Seagate ST3000DM001, one from 2012 and other from 2014, the 2nd one is empty. Both are directly connected to the SATA ports of a Gigabyte GA-C847N mini-ITX mobo with 2 GB RAM, running Ubuntu 14.04 from a flash drive (freshly booted, no extra software or drivers installed). There are about 200K files of sizes varying from a few KB to a few GB.
From the GA-C847N manual:
- 1 x SATA 6Gb/s connector (SATA3 0) supporting up to 1 SATA 6Gb/s device
- 2 x SATA 3Gb/s connectors (SATA2 1/2) supporting up to 2 SATA 3Gb/s device
- Seagate Barracuda ST3000DM001 3TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive
One HDD is connected on a SATA 3 connector and other in a SATA 2 connector.
Both filesystems are NTFS with the default block size (4KB).
Even if both HDDs were in SATA 1 mode, the advertised speed 1.5 Gbit/s (150 MB/s) speeds. I know this is a theoretical top speed, and I suppose the speed is shared between both HDDs (that is, 30 MBps each), but still, 60 MBps is nearly 1/3rd of (150 MB/s).
- Is my assumption that the total SATA speed is shared between multiple SATA HDDs correct?
- Why is this transfer so slow?