When is upgrading to a bigger NAS worth it?

When you're permanently above 70% utilization and drive growth (to larger models) isn't enough. Or when switching from RAID 1 to RAID 5/6.

Can I move drives from old NAS to new one?

Between compatible Synology DSM models often yes. Between brands (Synology → QNAP) never. Always back up before migration.

How long does NAS migration take?

Data copy 4-8 TB: 24-48 hours over 1 GbE. Live drive-size migration: 24 hours per drive. Plus setup time.

NAS Upgrade: 2-Bay → 4-Bay → 6-Bay Done Right

Updated: 2026-04-29

Your 2-bay NAS has been running for years – and is getting too small. Or your 4-bay fills faster every family vacation. Here's the honest migration guide, no hype.

When upgrade is due

2-bay → 4-bay: when you regularly cross 70% utilization and drive-size upgrades aren't worth it anymore. Also smart if you want to switch from RAID 1 to RAID 5/SHR-1 (more usable capacity at comparable safety).

4-bay → 6/8-bay: for critical data without backup, or when RAID 6 instead of RAID 5 makes sense (drive sizes 12 TB+). Also for multi-pool needs (see Calculator: up to 10 pools).

Drive growth as alternative

Before swapping the whole unit: can you just go to bigger drives?

Synology DSM allows online migration: swap drive by drive, volume grows after the last one.
4×8 TB → 4×16 TB SHR-1 doubles capacity without hardware upgrade.
Duration: ~24 hours per drive for resync, so 4 days total.

Pro: no new NAS purchase. Con: extended degraded-performance window.

Migration with new NAS

Variant A: Sequential migration.

Buy new NAS with new drives, set up in parallel
Create volume, configure RAID
Copy data via Synology Hyper Backup or rsync from old NAS (24-72 hours depending on volume)
Shut down old NAS, take new one into production
Old drives as off-site backup or sell

Variant B: Disk migration. On some Synology models it works: re-plug drives into the new NAS, volume is taken over. Riskier but faster. Only between compatible models (check DSM version notes).

Concrete 2026 picks

2-bay upgrade target: 4-bay Synology DS923+ (~$530) or Ugreen DXP4800 Plus (~$580) for 10 GbE.

4-bay upgrade target: 6-bay Synology DS1621+ (~$830) or DIY with Jonsbo N3 + N100 (~$700).

6-bay+ for power users: 8-bay TrueNAS build with Ryzen 5 + ECC RAM (~$1200) for ZFS RAIDZ2.

Common mistakes

No backup before migration. Migrations are the #1 cause of data loss.
Going RAID 6 with only 4 drives. Makes sense from 5+ drives. With 4 stick to RAID 5 or upgrade drive sizes.
Mixing old and new drives. Old drives in new RAID = next failure preprogrammed. Separate.