Busk: Created page with "Nice—those 10K SAS Hitachi drives are actually a really solid fit for ZFS if you tune it right. Let’s dial this in specifically for your setup. --- # 🧱 Your Drive..."

2026-03-28T19:24:33Z

Created page with "Nice—those **10K SAS Hitachi drives** are actually a really solid fit for ZFS if you tune it right. Let’s dial this in specifically for your setup. --- # 🧱 Your Drive..."

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Nice—those **10K SAS Hitachi drives** are actually a really solid fit for ZFS if you tune it right. Let’s dial this in specifically for your setup.

---

# 🧱 Your Drive

## Hitachi DKR5E-J1R2SS

![Image](https://cdn11.bigcommerce.com/s-017c0/images/stencil/1280x1280/products/12022/50761/3282390-E_1__08710.1680120086.JPG?c=2)

![Image](https://m.media-amazon.com/images/I/614y6FroB-L._AC_UF894%2C1000_QL80_.jpg)

![Image](https://www.disctech.com/SCASite/product_images/0B23727_1000-1.jpg)

![Image](https://i.ebayimg.com/images/g/YakAAeSwtkhoFgAO/s-l400.jpg)

### Key characteristics:

* ~120–180 IOPS per drive
* Low latency vs SATA, but still **spinning disk**
* Enterprise reliability (great for ZFS)
* Likely **512e or 4K sectors** (we’ll force correct alignment)

---

# 🎯 Goals for ZFS Tuning

You want to optimize for:

* LXD containers + VMs
* Mixed workloads (random IO heavy)
* Stability over raw throughput

---

# ⚙️ Step 1 — Create ZFS Pool (IMPORTANT SETTINGS)

Assuming HBA mode and multiple disks (recommended RAIDZ or mirrors):

### 🔥 Best layout options:

* **Mirrors (RAID10 equivalent)** → BEST performance
* **RAIDZ2** → BEST safety (recommended if ≥6 disks)

---

### Example (mirrors)

```bash
zpool create -o ashift=12 HDD \
mirror /dev/sdb /dev/sdc \
mirror /dev/sdd /dev/sde
```

### Example (RAIDZ2)

```bash
zpool create -o ashift=12 HDD \
raidz2 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg
```

---

## 🔑 Why `ashift=12` matters

* Forces 4K alignment (even if drive lies)
* Prevents **massive write amplification**

👉 Always do this. No exceptions.

---

# ⚙️ Step 2 — ZFS Dataset Tuning (CRITICAL)

For LXD workloads:

```bash
zfs set atime=off HDD
zfs set compression=lz4 HDD
zfs set xattr=sa HDD
zfs set acltype=posixacl HDD
```

---

## 🧠 Recordsize tuning (VERY important)

### For general LXD pool:

```bash
zfs set recordsize=128K HDD
```

### For VM disks (zvols):

```bash
zfs set volblocksize=16K HDD/vm
```

👉 Why:

* 128K = good throughput default
* 16K = better for random IO (VMs, DB)

---

# ⚙️ Step 3 — LXD Storage Pool

```bash
lxc storage create HDD zfs source=HDD
```

---

# ⚙️ Step 4 — Special LXD tuning

### For containers:

ZFS dataset works great as-is.

### For VMs:

```bash
lxc storage set HDD volume.zfs.block_mode=true
```

👉 This uses zvols instead of files → better performance

---

# ⚡ Optional (BUT HIGHLY RECOMMENDED)

## 🚀 Add SLOG (for sync writes)

Without SLOG:

* Sync writes = slow (HDD latency)

With SLOG:

* Huge boost for:

* databases
* fsync-heavy workloads
* Kubernetes / etcd

---

### Best SLOG device:

* NVMe with power-loss protection

Example:

```bash
zpool add HDD log /dev/nvme0n1
```

---

## 🧠 L2ARC (read cache)

Only add if:

* RAM < working set

```bash
zpool add HDD cache /dev/nvme1n1
```

👉 Not critical unless heavy reads

---

# ⚙️ Step 5 — Kernel tuning (small but helpful)

```bash
echo 1 > /sys/module/zfs/parameters/zfs_prefetch_disable
```

👉 Disables prefetch (better for random workloads)

---

# ⚠️ What NOT to do

❌ Don’t use:

* RAID controller + ZFS (double abstraction)
* RAID5 on controller (write hole risk)
* ashift=9 (huge mistake on modern disks)

---

# 🧪 Expected Performance

With mirrors:

* ~2x IOPS scaling
* Great for VMs

With RAIDZ2:

* Better capacity
* Lower IOPS (write penalty)

---

# 🏆 Final Recommended Setup (for YOU)

Given your setup:

### If you want performance:

👉 **Mirrors + ZFS**

* Best VM performance
* Scales well

### If you want capacity + safety:

👉 **RAIDZ2 + ZFS**

* Survives 2 disk failures
* Still solid performance

---

# 🔥 My Personal Pick for Your Use Case

Since you're running:

* LXD cluster
* likely DB / infra workloads

👉 I would do:

**Mirrors + ZFS + optional NVMe SLOG**

---

# 💡 Bonus: LXD Multi-Pool Strategy

You can do:

```bash
lxc storage create fast zfs source=SSDPOOL
lxc storage create HDD zfs source=HDD
```

Then:

* Put VMs → fast
* Backups / bulk → HDD

---

# 👍 Final Take

Your **10K SAS drives + ZFS (HBA mode)**:

* Extremely reliable
* Predictable performance
* WAY safer than RAID for long-term integrity

---

If you want next step, I can:

* Map your exact number of disks → best vdev layout
* Or tune specifically for PostgreSQL / your monitoring stack

Zfs hdd tuning - Revision history

Busk: Created page with "Nice—those **10K SAS Hitachi drives** are actually a really solid fit for ZFS if you tune it right. Let’s dial this in specifically for your setup. --- # 🧱 Your Drive..."

Busk: Created page with "Nice—those 10K SAS Hitachi drives are actually a really solid fit for ZFS if you tune it right. Let’s dial this in specifically for your setup. --- # 🧱 Your Drive..."