Oracle ZFS Storage Appliance Administration Manual page 368

Project and Share Properties
BUI value
Fletcher 2 (Legacy)
Fletcher 4 (Standard)
SHA-256 (Extra Strong)
SHA-256-MAC
Cache device usage
The cache device usage property controls whether cache devices are used for the share. By
default, all datasets make use of any cache devices on the system. Cache devices are configured
as part of the storage pool and provide an extra layer of caching for faster tiered access. For
more information on cache devices, see
independent of whether there are any cache devices currently configured in the storage pool.
For example, it is possible to have this property set to "all" even if there are no cache devices
present. If any such devices are added in the future, the share will automatically take advantage
of the additional performance. This property does not affect use of the primary (DRAM) cache.
BUI Value
All data and metadata
Metadata only
Do not use cache devices
Synchronous write bias
The synchronous write bias property controls the behavior when servicing synchronous writes.
By default, the system optimizes synchronous writes for latency, which leverages the log
devices to provide fast response times. In a system with multiple disjointed filesystems, this can
cause contention on the log devices that can increase latency across all consumers. Even with
multiple filesystems requesting synchronous semantics, it may be the case that some filesystems
are more latency-sensitive than others.
A common case is a database that has a separate log. The log is extremely latency sensitive, and
while the database itself also requires synchronous semantics, it is heavier bandwidth and not
368 Oracle ZFS Storage Appliance Administration Guide, Release OS8.6.x • September 2016
CLI value
fletcher2
fletcher4
sha256
sha256mac
"Configuring Storage" on page
CLI Value
all
metadata
none
Description
16-bit fletcher checksum
32-bit fletcher checksum
SHA-256 checksum
88. This property is
Description
All normal file or LUN data is
cached, as well as any metadata.
Only metadata is kept on cache
devices. This allows for rapid
traversal of directory structures, but
retrieving file contents may require
reading from the data devices.
No data in this share is cached on the
cache device. Data is only cached in
the primary cache or stored on data
devices.