Chapter 9. Advanced features for storage efficiency 473
General-purpose volumes
Most general-purpose volumes are used for highly compressible data types, such as home
directories, CAD/CAM, oil and gas geo-seismic data and log data. Storing such types of data
in compressed volumes provides immediate capacity reduction to the overall used space.
More space can be provided to users without any change to the environment.
Many file types can be stored in general-purpose servers. However, for practical information,
the estimated compression ratios are based on actual field experience.
File systems that contain audio, video files, and compressed files are not good candidates for
compression. The overall capacity savings on these file types are minimal.
Databases
Database information is stored in table space files. It is common to observe high compression
ratios in database volumes. Examples of databases that can greatly benefit from Real-Time
Compression are IBM DB2®, Oracle and Microsoft SQL Server.
Virtualized infrastructures
The proliferation of open systems virtualization in the market has increased the use of storage
space, with more virtual server images and backups kept online. The use of compression
reduces the storage requirements at the source.
Examples of virtualization solutions that can greatly benefit from Real-time Compression are
VMware, Microsoft Hyper-V, and KVM.
Log server data stores
Logs are a critical part for any information technology (IT) department in any organization.
Log aggregates or syslog servers are a central point for the administrators, and immediate
access and a smooth work process is necessary. Log server data stores are good candidates
for Real-time Compression.
9.4.2 Real-time Compression concepts
RACE technology is based on over 70 patents that are not primarily about compression.
Instead, they define how to make industry-standard Lempel-Ziv (LZ) compression of primary
storage operate in real-time and allow random access. The primary intellectual property
behind this is the RACE engine.
At a high level, the IBM RACE component compresses data that is written into the storage
system dynamically. This compression occurs transparently, so Fibre Channel and iSCSI
connected hosts are not aware of the compression. RACE is an online compression
technology, which means that each host write is compressed as it passes to the disks. This
technique has a clear benefit over other compression technologies that are post-processing
based.
Important: Some databases offer optional built-in compression. Generally, do not
compress already compressed database files.
Tip: Virtual machines with file systems that contain compressed files are not good
candidates for compression, as described in “Databases”.
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