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object type" and check for a higher rate of sustained DDT operations (Data Duplication Table
operations) as compared to ZFS operations. If this is happening, more I/O is for serving the
deduplication table rather than file I/O.
To use deduplication with encryption, keep in mind that only AES with the CCM mode
encryption is compatible with deduplication. For more information, see
Keys" on page
582.
Data compression
The data compression property controls whether data is compressed before being written
to disk. Shares can optionally compress data before writing to the storage pool. This allows
for much greater storage utilization at the expense of increased CPU utilization. By default,
no compression is done. If the compression does not yield a minimum space savings, it is
not committed to disk to avoid unnecessary decompression when reading back the data.
Before choosing a compression algorithm, it is recommended that you perform any necessary
performance tests and measure the achieved compression ratio.
BUI value
Off
LZJB (Fastest)
GZIP-2 (Fast)
GZIP (Default)
GZIP-9 (Best Compression)
Checksum
The checksum property controls the checksum used for data blocks. On the appliance, all data
is checksummed on disk, and in such a way to avoid traditional pitfalls (phantom reads and
write in particular). This allows the system to detect invalid data returned from the devices.
The default checksum (fletcher4) is sufficient for normal operation, but users can increase the
checksum strength at the expense of additional CPU load. Metadata is always checksummed
using the same algorithm, so this only affects user data (files or LUN blocks).
CLI value
off
lzjb
gzip-2
gzip
gzip-9
Project and Share Properties
"Managing Encryption
Description
No compression is done
A simple run-length encoding that
only works for sufficiently simple
inputs, but doesn't consume much
CPU.
A lightweight version of the gzip
compression algorithm.
The standard gzip compression
algorithm.
Highest achievable compression
using gzip. This consumes a
significant amount of CPU and can
often yield only marginal gains.
Shares and Projects
367
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