Spent the day experimenting:
- Noticed that one of the server's cores was pegged at 100% during network file transfers or even SATA to SATA file copying.
- File copying SATA to SATA was also very slow.
- By repeatedly copying different large files from the server to the workstation I noticed that the transfer speed did start around 60MB/s but then rapidly deteriorated down to 10 MB/s.
- There are 3 drives on my server: BOOT, MEDIA, MEDIA MIRROR (the media drive gets synced to the Media Mirror once a week using Allway sync). All the network shares are on the MEDIA drive but as an experiment I shared a test folder on the BOOT and MEDIA MIRROR drives and both those drives had normal network transfer rates of around 100MB/s.
I figured I had a bad drive, or a bad SATA port or a bad SATA cable, but the first thing I did was clean each of the SATA connectors on the motherboard with CRC contact cleaner. Sure enough that fixed the problem.
It's bizarre because I would have expected to see some cable CRC errors in the log or on the drives SMART data but nothing showed up.
So clean your SATA ports!
