ZFS recordsize Property

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The recordsize property of ZFS datasets is used to specify the maximum block size for files in the file system. Often, this property does not need to be changed, but for workloads that create very large files, increasing the value of recordsize can deliver a performance benefit. The chosen size must be a power of 2 with the minimum allowed size being 512 bytes. For ZFS on Linux, the maximum value is 1MiB in version 0.6.5. Prior to this release, the maximum value was 128K (which was also the default setting for Lustre 2.10 and earlier).

The default setting is not sufficient to sustain the performance of throughput oriented workloads that are typical of the I/O patterns for OSTs, and it is recommended to increase the recordsize to 1MiB (1024K), in order to better match the Lustre IO transaction sizes for block I/O. This is the default for ZFS OSTs with Lustre 2.11 and later.