diff --git a/en_US.ISO8859-1/books/handbook/zfs/chapter.xml b/en_US.ISO8859-1/books/handbook/zfs/chapter.xml
--- a/en_US.ISO8859-1/books/handbook/zfs/chapter.xml
+++ b/en_US.ISO8859-1/books/handbook/zfs/chapter.xml
@@ -2926,6 +2926,72 @@
However since quotas do not consider compression, more data
may be written than would fit with uncompressed
backups.
+
+
+ Zstandard Compression
+
+ In OpenZFS 2.0, a new compression
+ algorithm was added. Zstandard (Zstd)
+ offers higher compression ratios than the default
+ LZ4 while offering much greater speeds
+ than the alternative, gzip.
+ OpenZFS 2.0 is available starting with
+ &os; 12.1-RELEASE via
+ sysutils/openzfs and has been the
+ default in &os; 13-CURRENT since September 2020, and
+ will by in &os; 13.0-RELEASE.
+
+ Zstd provides a large selection of
+ compression levels, providing fine-grained control over
+ performance versus compression ratio. One of the main
+ advantages of Zstd is that the
+ decompression speed is independent of the compression
+ level. For data that is written once but read many times,
+ Zstd allows the use of the highest
+ compression levels without a read performance
+ penalty.
+
+ Even when data is updated frequently, there are often
+ performance gains that come from enabling compression. One
+ of the biggest advantages comes from the compressed ARC
+ feature. ZFS's Adaptive Replacement
+ Cache (ARC) caches the compressed version
+ of the data in RAM, decompressing it each
+ time it is needed. This allows the same amount of
+ RAM to store more data and metadata,
+ increasing the cache hit ratio.
+
+ ZFS offers 19 levels of
+ Zstd compression, each offering
+ incrementally more space savings in exchange for slower
+ compression. The default level is
+ zstd-3 and offers greater compression
+ than LZ4 without being significantly
+ slower. Levels above 10 require significant amounts of
+ memory to compress each block, so they are discouraged on
+ systems with less than 16 GB of RAM.
+ ZFS also implements a selection of the
+ Zstd fast levels,
+ which get correspondingly faster but offer lower
+ compression ratios. ZFS supports
+ zstd-fast-1 through
+ zstd-fast-10,
+ zstd-fast-20 through
+ zstd-fast-100 in increments of 10, and
+ finally zstd-fast-500 and
+ zstd-fast-1000 which provide minimal
+ compression, but offer very high performance.
+
+ If ZFS is not able to allocate the required memory to
+ compress a block with Zstd, it will fall
+ back to storing the block uncompressed. This is unlikely
+ to happen outside of the highest levels of
+ Zstd on systems that are memory
+ constrained. The sysctl
+ kstat.zfs.misc.zstd.compress_alloc_fail
+ counts how many times this has occurred since the
+ ZFS module was loaded.
+