12 guides
Hard Drives & Storage
Best drives for NAS, SSD caching, RAID, ZFS and capacity planning.
Most NAS storage questions are really about trade-offs between capacity, redundancy and the time a rebuild takes. These guides cover choosing hard drives (CMR, not SMR), deciding between RAID 5, RAID 6 and SHR, when SSDs are worth it, how much RAM a NAS needs, which filesystem to use, and how to spot and replace a failing drive before it takes the array with it.
- Drives: best hard drives for a NAS, CMR vs SMR explained and hard drive vs SSD in a NAS.
- Redundancy: RAID 5 vs RAID 6 vs SHR and how many drive bays you need.
- When drives fail: SMART attributes that predict drive failure and how to replace a failed drive and survive the rebuild.
Index
All hard drives & storage guides
- 01Btrfs vs ZFS vs ext4 on a NAS: How to Choose a FilesystemBtrfs vs ZFS vs ext4 for a NAS: data checksums, self-healing, snapshots and compression compared, plus why Btrfs RAID 5/6 is unsafe and Synology's Btrfs is not.Sep 24, 2026 · 5 min
- 02How Much RAM Does a NAS Need? (ZFS, Docker and VMs)How much RAM a NAS actually needs, by workload: file sharing, Docker containers, Immich, VMs and ZFS. Why the 1GB-per-TB rule is wrong, plus ECC and upgrade advice.Sep 21, 2026 · 5 min
- 03How to Replace a Failed NAS Drive and Survive the RebuildReplace a failed NAS drive safely: verify backups, find the disk by serial, pick a CMR replacement, survive the rebuild and run a scrub.Sep 9, 2026 · 5 min
- 04SMART Attributes That Actually Predict NAS Drive FailureWhich SMART attributes predict hard drive failure — 5, 187, 188, 197 and 198 — which ones people misread, and how to schedule tests on a NAS.Sep 3, 2026 · 5 min
- 05ZFS Snapshots vs Backups: What Each One ProtectsZFS snapshots vs backups explained: what snapshots protect, why local snapshots are not backups, how replication works and how to test recovery.Aug 4, 2026 · 5 min
- 06SSD Endurance Calculator: TBW, DWPD and How Long a NAS SSD Will LastEstimate how many years an SSD lasts in a NAS from its TBW rating and your daily writes, convert TBW to DWPD, and compare NAS SSD endurance ratings.Jul 26, 2026 · 10 min
- 07RAID 5 vs RAID 6 vs SHR: Which Should You Choose?RAID 5 vs RAID 6 vs Synology SHR: compare usable capacity, fault tolerance, mixed-drive expansion, rebuild risk and the best choice for each NAS.Jul 24, 2026 · 5 min
- 08Best SSD for NAS in 2026 (Cache, Pools & All-Flash)Best SSD for NAS in 2026. Top picks for cache, all-flash pools and metadata, plus what matters: endurance (TBW), DRAM cache and power-loss protection.Jul 1, 2026 · 5 min
- 09CMR vs SMR Hard Drives Explained (and Why It Matters for NAS)CMR vs SMR explained: the difference between the two recording methods, why SMR is risky for NAS/RAID rebuilds, and how to identify CMR drives.Jul 1, 2026 · 5 min
- 10Hard Drive vs SSD for a NAS: Which Should You Use?Hard drive vs SSD for a NAS: cost per TB, speed, noise and power compared, plus when an all-flash NAS or SSD cache is worth it.Jul 1, 2026 · 5 min
- 11Best Hard Drives for NAS in 2026 (CMR vs SMR, Sizes & Reliability)Best NAS hard drives for 2026, backed by data: CMR vs SMR (which WD Red to avoid), WD Red Pro vs IronWolf Pro vs Toshiba N300, and the best value capacity.Jul 1, 2026 · 5 min
- 12How Many Drive Bays Does Your NAS Need? (2 vs 4 vs 6+)How many NAS drive bays do you need? 2 vs 4 vs 6+ bays compared for capacity, redundancy and future growth — with a simple decision guide.Jul 1, 2026 · 4 min