Free Betterbsd Mastery Advanced Zfs Pdf · Quick & Recent

The ZFS Intent Log (ZIL) is not a write cache. Repeat: not a cache.

It’s a consistency journal for synchronous writes (NFS, databases). By default, it lives on your main pool. A Separate LOG device (SLOG) is only for the ZIL. free betterbsd mastery advanced zfs pdf

Here’s the advanced trick: Your SLOG doesn’t need to be large—just big enough for ~10 seconds of sync writes (often 16-64 GB). And it doesn’t need to be fast on reads—only on low-latency writes. The ZFS Intent Log (ZIL) is not a write cache

But the killer insight: If your SLOG dies, ZFS simply falls back to the main pool’s internal ZIL. You don’t lose data. You just lose performance. So don’t fear using a cheap Optane or small NVMe. Fear using a slow SLOG that drags your sync writes to a crawl. Recommended pool properties and defaults for BetterBSD

Every dataset can inherit or override properties. Mastery means setting recordsize with intent.

And atime=off on anything that isn't a mail server? That’s not optimization—that’s hygiene.