I bought an 8TB Seagate ST8000DM004-2CX188 second-hand and did not test it properly at the time. I know this is a shingled magnetic recording (SMR) drive, but I have used a similar model for years for archiving large 4K video files. The drive initially writes at a normal speed, then quickly falls below 1 MB/s. It is empty, so destructive troubleshooting is fine. Multiple long and short SeaTools tests, along with other drive checks, report no problems, and the drive surface appears healthy. I have formatted it with NTFS and tried different allocation-unit sizes, including 8 KB. When copying files larger than 4 GB, I would normally expect roughly 120 MB/s based on my other drive. Is there anything else I can try, or is this simply severe SMR write behavior or a failing drive?
3 Answers
SMR drives can sustain decent speed briefly until their write cache fills. After that, the drive has to reorganize overlapping shingles, and performance can collapse, especially if background housekeeping is already running. Large sequential files are the best-case workload, so dropping below 1 MB/s even with those suggests the drive may be unusually busy, badly fragmented internally, or defective despite passing basic diagnostics. Let it sit powered on and idle for several hours, then retry a single sequential write to the empty drive.
Since the disk is empty, you could secure-erase or fully overwrite it and then test again with one large sequential write. A complete write may give the SMR translation layer a clean starting point, but it will not turn this model into a conventional recording drive. If it still starts normally and quickly falls under 1 MB/s afterward, replacing or returning it is probably more sensible than relying on it for archival storage.
First confirm the measurement with a disk benchmark or a single large-file copy, rather than judging from many files being copied at once. Also check the connection, SATA cable, controller mode, negotiated link speed, and SMART data—especially reallocated, pending, or uncorrectable sectors. A clean surface test does not rule out firmware, cache, or mechanical problems.
The slow behavior happens while writing a single file larger than 4 GB, not just during a batch of small files. Several full tests also take hours but report a clean surface, so I may try a full destructive overwrite before giving up.