Hardware Compression - EMC DL3D 1500 Administrator's Manual

About the DL3D 1500/3000
unique block so that only one copy of that data block will exist on
disk. This description (signatures and pointers) of the de-duplicated
data is referred to as the metadata index and is stored separately from
the backup data on a RAID 6 LUN on the disk array in the DL3D 3000
and on a RAID1 LUN in the DL3D 1500. A metadata index is stored
for all data de-duplicated within the DL3D.
As additional backup data is written to the DL3D, its data is also
broken down into variable length blocks whose signatures are
compared against those for existing unique blocks. Only new unique
blocks are stored along with pointers to existing unique blocks in the
appropriate sequence that can be used to reconstitute the data. The
sections "Configuring and Managing Disk Backup" on page 95 and
"Configuring and Managing Virtual Tape Libraries" on page 55
contain more information on enabling data de-duplication.

Hardware compression

The DL3D 1500 and DL3D 3000 appliances are configured with
hardware-based compression cards. These compression cards
installed in your system allow unique data that has been through the
de-duplication process to be further compressed at a ratio of 2:1. This
enables you to maximize the storage capacity of your system as well
as increase overall backup performance.
22 EMC DL3D 1500 and DL3D 3000 Administrator's Guide