From bdbecadbfab5c8072b3201a893a2c736ceb1414b Mon Sep 17 00:00:00 2001 From: George Melikov Date: Sun, 29 Sep 2024 01:17:44 +0300 Subject: [PATCH] man: update recordsize max size info Reflect https://github.com/openzfs/zfs/commit/f2330bd1568489ae1fb16d975a5a9bcfe12ed219 change in our man pages and add some context. Wording is primarily copy-pasted from code comments. Signed-off-by: George Melikov --- man/man4/zfs.4 | 5 +++++ man/man7/zfsprops.7 | 12 +++++++++++- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/man/man4/zfs.4 b/man/man4/zfs.4 index 1f6be3963a3b..6840dc3171b9 100644 --- a/man/man4/zfs.4 +++ b/man/man4/zfs.4 @@ -1749,6 +1749,11 @@ Therefore, we formerly forbade creating blocks larger than 1M. Larger blocks could be created by changing it, and pools with larger blocks can always be imported and used, regardless of this setting. +.Pp +Note that it is still limited by default to +.Ar 1 MiB +on x86_32, because Linux's +3/1 memory split doesn't leave much room for 16M chunks. . .It Sy zfs_allow_redacted_dataset_mount Ns = Ns Sy 0 Ns | Ns 1 Pq int Allow datasets received with redacted send/receive to be mounted. diff --git a/man/man7/zfsprops.7 b/man/man7/zfsprops.7 index f33b663d1196..72a64f5ecf37 100644 --- a/man/man7/zfsprops.7 +++ b/man/man7/zfsprops.7 @@ -1527,11 +1527,21 @@ and less than or equal to If the .Sy large_blocks feature is enabled on the pool, the size may be up to -.Ar 1 MiB . +.Ar 16 MiB . See .Xr zpool-features 7 for details on ZFS feature flags. .Pp +However, blocks larger than +.Ar 1 MiB +can have an impact on i/o latency (e.g. tying up a spinning disk for +~300ms), and also potentially on the memory allocator. +Note that maximum size is still limited by default to +.Ar 1 MiB +on x86_32, see +.Sy zfs_max_recordsize +module parameter. +.Pp Changing the file system's .Sy recordsize affects only files created afterward; existing files are unaffected.