From 51e544b624b174a3babcde912f5c15407e0965c0 Mon Sep 17 00:00:00 2001 From: Thomas Lamprecht Date: Fri, 8 Nov 2019 14:42:20 +0100 Subject: [PATCH] followup: some clarifcations, small aditions Signed-off-by: Thomas Lamprecht --- local-zfs.adoc | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/local-zfs.adoc b/local-zfs.adoc index f4db54b..15a88bb 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -441,11 +441,11 @@ pool is used to store metadata, deduplication tables, and optionally small file blocks. A `special` device can improve the speed of a pool consisting of slow spinning -hard disks with a lot of changing metadata. For example workloads that involve -creating or deleting a large number of files will benefit from the presence of -a `special` device. ZFS datasets can be configured to store whole small files -on the `special` device which can further improve the performance. Use SSDs for -the `special` device. +hard disks with a lot of metadata changes. For example workloads that involve +creating, updating or deleting a large number of files will benefit from the +presence of a `special` device. ZFS datasets can also be configured to store +whole small files on the `special` device which can further improve the +performance. Use fast SSDs for the `special` device. IMPORTANT: The redundancy of the `special` device should match the one of the pool, since the `special` device is a point of failure for the whole pool. @@ -466,14 +466,14 @@ two in the range between `512B` to `128K`. After setting the property new file blocks smaller than `size` will be allocated on the `special` device. IMPORTANT: If the value for `special_small_blocks` is greater than or equal to -the `recordsize` of the dataset, *all* data will be written to the `special` -device, so be careful! +the `recordsize` (default `128K`) of the dataset, *all* data will be written to +the `special` device, so be careful! Setting the `special_small_blocks` property on a pool will change the default value of that property for all child ZFS datasets (for example all containers in the pool will opt in for small file blocks). -.Opt in for small file blocks pool-wide: +.Opt in for all file smaller than 4K-blocks pool-wide: zfs set special_small_blocks=4K -- 2.39.2