I'm experiencing a strange issue with one of my SATA HDDs. Basically I have two internal HDDs that I am connecting to the PC through a SATA-to-USB adapter. I am not keeping them inside the PC since they are only used for backups.
Anyway, one of these HDDs has a strange issue such that when I copy large amounts of data - single large file OR multiple small files - of over 1GB, the copy process slows down dramatically. The average transfer rate is of 30MB/s and works well if the copy operation does not exceed ~700MB.
If the write operation is large, after ~30 seconds, the estimated transfer speed starts dropping down until it eventually reaches ~2MB/s!
I have re-formatted the drive a number of times with FAT / NTFS and different block sizes. I have also toggled the Windows caching option with no effect. I have run Windows CheckDisk as well as various tests from HDDScan and both had no issues to report. S.M.A.R.T statistics also seems OK.
The other HDD runs smoothly with a constant ~30MB/s transfer rate (using the same adapter).
Anyone has any idea what the issue might be? Thanks!
