NAS questions, answered
79 single-question answers to the things people actually search when a drive fails, a NAS won’t take a disk, or a rebuild drags on. Each answer leads with the verdict, cites manufacturer documentation, and links live Amazon.ca CMR drives in CAD where a drive is the fix.
Replacing a failed drive
Swapping a dead or failing drive without losing data — sizes, brands, hot-swap and rebuilds.
- Can I replace a failed Synology drive with a bigger one?
- Does a replacement NAS drive have to be the same brand?
- Can I hot swap a drive in a Synology NAS?
- What drive should I buy to replace a failed drive in SHR?
- Why is the Repair option not showing in Synology Storage Manager?
- How long does a Synology RAID rebuild take?
- Can I replace a drive in RAID 5 with a smaller one?
- Should I replace all NAS drives at once or one at a time?
SMR vs CMR
Which drives are shingled, why it breaks RAID rebuilds, and how to check a model.
- Is the WD Red 4TB SMR or CMR?
- Is the WD Red 6TB SMR or CMR?
- Are Seagate BarraCuda drives OK for a NAS?
- What is the difference between WD Red and WD Red Plus?
- Why is my RAID rebuild taking days?
- Can SMR drives be used in RAID?
- How do I tell if my hard drive is SMR or CMR?
- Are all IronWolf drives CMR?
- Is the Toshiba N300 CMR?
- Can I mix SMR and CMR drives in a NAS?
Drive compatibility
What drives work in Synology, and whether you still need branded or NAS-specific drives.
- Do I need Synology-branded drives?
- Does Synology still block third-party drives?
- Can I use any hard drive in a Synology NAS?
- Are WD Red drives compatible with Synology?
- Do I need NAS drives, or can I use desktop drives?
- Can I use an NVMe SSD for storage in a Synology NAS?
- What drives work with a UGREEN NAS?
- Are Seagate Exos drives good for a NAS?
- What drives work in the Synology DS925+?
- What drives work in the Synology DS1525+?
- What drives work in the Synology DS1522+?
- What drives work in the Synology DS224+?
- What drives work in the Synology DS423+?
- What drives work in the Synology DS923+?
- What drives work in the QNAP TS-464?
- What drives work in the QNAP TS-264?
- What drives work in the UGREEN DXP4800 Plus?
- What drives work in the UGREEN DXP2800?
Drive health & SMART
Reading SMART data, bad sectors, temperature and how long NAS drives really last.
RAID & volumes
Degraded vs crashed pools, RAID 5 safety, SHR, and changing RAID type safely.
- What should I do when my Synology volume has crashed?
- What is the difference between a degraded and a crashed volume?
- Is my data safe if one drive fails in RAID 5?
- What is SHR and should I use it?
- Can I change RAID type without losing data?
- How long does it take to rebuild a 4TB drive in a NAS?
- How long does it take to rebuild an 8TB drive in a NAS?
- How long does it take to rebuild a 12TB drive in a NAS?
- How long does it take to rebuild a 16TB drive in a NAS?
- How long does it take to rebuild a 20TB drive in a NAS?
- Can I use my NAS during a RAID rebuild?
- Why did my RAID rebuild fail?
- Does RAID rebuild time depend on how full the volume is?
- Should I upgrade to RAID 6 for large drives?
QNAP
Compatible drives, unrecognised drives, migration and QNAP's flexible-RAID options.
Network & access
Why Windows 11, macOS or remote access can't reach your NAS — SMB signing, guest logins, NTLM, SMB1, QuickConnect and VPN.
- Why can't Windows 11 see my Synology NAS?
- How do I fix "Authentication failed because NTLM authentication has been disabled"?
- Why does my NAS say "network path was not found"?
- Why does Windows say my NAS username or password is incorrect?
- How do I map a Synology shared folder as a network drive in Windows?
- Is it safe to enable SMB1 for an old NAS?
- Why did Windows 11 24H2 break my NAS connection?
- How do I connect to a Synology NAS from a Mac?
- Why is my NAS not showing up in File Explorer network?
- What is the difference between SMB and NFS on a NAS?
- Why is Synology QuickConnect not working?
- Why can't I access my NAS remotely?
UGREEN & TerraMaster
Bring-your-own-drive policies and flexible RAID on UGREEN NASync and TerraMaster.
Testing, noise & temperature
Burning in a new drive, clicking sounds, and how loud NAS drives get.