Western Digital 40GB
Other HDD
Part number WD400JD · HDD. If your machine is listed below, this drive is officially supported — not a forum workaround.
Check WD400JD price on Amazon partner link
No series-level recording rating is on file for this part number yet — check the exact model for CMR vs SMR before buying it as a large cold copy (SMR is the one trait that makes a 16 TB+ backup copy painfully slow). The 3-2-1 guide and the backup tools encyclopedia cover what to schedule it with.
Compatibility verdict
It appears on the official compatibility lists of 2 machines and series — 2 QNAP. Check the class badge above: drives tagged NAS or Enterprise are built for 24/7 multi-bay operation. Desktop-class drives often lack vibration resistance and are usually absent from vendor HCLs. No series-level recording rating is on file for this part number yet, so check CMR vs SMR on the exact model before buying for an array.
Compatible NAS models
Same-capacity alternatives
Other drives listed at 40 GB capacity, ranked by how many machines list them:
Quick answers
Is the WD400JD officially compatible with my NAS?
It appears on the official compatibility lists of 2 machines and series — 2 QNAP. Every machine page linked below shows the vendor's own list entry, refreshed daily.
Is the WD400JD a good NAS drive?
Check the class badge above: drives tagged NAS or Enterprise are built for 24/7 multi-bay operation. Desktop-class drives often lack vibration resistance and are usually absent from vendor HCLs. No series-level recording rating is on file for this part number yet, so check CMR vs SMR on the exact model before buying for an array.
Can I use the WD400JD for a 3-2-1 cold backup copy?
No series-level recording rating is on file for this part number yet — check the exact model for CMR vs SMR before buying it as a large cold copy (SMR is the one trait that makes a 16 TB+ backup copy painfully slow). The 3-2-1 guide and the backup tools encyclopedia cover what to schedule it with.
What are alternatives to the WD400JD?
At the same capacity, the most widely listed alternatives are Seagate ST340215AS (2 machines), Seagate ST340815AS (2 machines). The full ranked list is below.