Western Digital Ultrastar DC HC550 16TB
Enterprise HDD
Part number WUH721816AL5204 · Ultrastar DC HC550 series · NL-SAS 12Gb/s. If your machine is listed below, this drive is officially supported — not a forum workaround.
Part of the Western Digital Ultrastar DC HC550 series →
Check WUH721816AL5204 price on Amazon partner link
Specifications are the manufacturer's published ratings for this product series; verify the exact part number before purchase.
Rated CMR (conventional magnetic recording) — the right recording type for a large cold copy. CMR keeps a full-library backup pass fast even at 16–24 TB, which is the whole point of the offline slot in a 3-2-1 plan: rotate two drives monthly, keep one powered off, and the backup tooling (Veeam, Duplicati, Hyper Backup, HBS 3) does the scheduling. Full rule and vendor tool table: 3-2-1 for NAS.
Compatibility verdict
It appears on the official compatibility lists of 8 machines and series — 7 QNAP, 1 Asustor. This is a Enterprise-class drive: rated for heavier sustained workloads than desktop drives. It is a strong pick for a NAS running 24/7, large-array rebuilds or camera workloads, and enterprise lines are also the drives most widely listed across all five vendors' HCLs. Its series rating is on file as CMR (conventional) — what RAID rebuilds and full-library copies want.
Compatible NAS models
Same-capacity alternatives
Other drives listed at 16 TB capacity, ranked by how many machines list them:
Quick answers
Is the WUH721816AL5204 officially compatible with my NAS?
It appears on the official compatibility lists of 8 machines and series — 7 QNAP, 1 Asustor. Every machine page linked below shows the vendor's own list entry, refreshed daily.
Is the WUH721816AL5204 CMR or SMR?
As a Western Digital Ultrastar DC HC550 drive, it is rated CMR. CMR (conventional magnetic recording) is what a RAID array wants: SMR drives slow rebuilds dramatically. See the <a href="/faq/cmr-vs-smr-nas-drives/">CMR vs SMR guide</a> for the full series table.
Is the WUH721816AL5204 a good NAS drive?
This is a Enterprise-class drive: rated for heavier sustained workloads than desktop drives. It is a strong pick for a NAS running 24/7, large-array rebuilds or camera workloads, and enterprise lines are also the drives most widely listed across all five vendors' HCLs. Its series rating is on file as CMR (conventional) — what RAID rebuilds and full-library copies want.
Can I use the WUH721816AL5204 for a 3-2-1 cold backup copy?
Rated CMR (conventional magnetic recording) — the right recording type for a large cold copy. CMR keeps a full-library backup pass fast even at 16–24 TB, which is the whole point of the offline slot in a 3-2-1 plan: rotate two drives monthly, keep one powered off, and the backup tooling (Veeam, Duplicati, Hyper Backup, HBS 3) does the scheduling. Full rule and vendor tool table: 3-2-1 for NAS.
What are alternatives to the WUH721816AL5204?
At the same capacity, the most widely listed alternatives are Seagate ST16000NM001G (314 machines), Toshiba MG08ACA16TE (299 machines), Seagate ST16000NE000 (294 machines). The full ranked list is below.