Load Source Specify Features; Disk Protection And Hardware Compression; Device Parity Protection - IBM eserver i5 Handbook

Draft Document for Review October 18, 2004

Load source Specify Features

Beginning with the V5R1 announcement, one of the following load source specify
codes is required on all initial orders of an iSeries server:
#0829 - #4318 Load Source specify
#0830 - #4319 Load Source specify
#0834 - #4326 Load Source specify
#0835 - #4327 Load Source specify
Manufacturing uses this specify to place the corresponding disk unit feature in
the load source position. These specify codes can be changed on server
upgrades or on simple MES orders.
Effective September 1, 2004 feature #4318 is withdrawn for new orders.
Coversions to feature remain available.

Disk protection and hardware compression

This section discusses the functions that can be used to protect iSeries disk
drives.

Device parity protection

Device parity protection is a hardware function that protects data from being lost
because of a disk unit failure or damage to a disk. Calculating and saving a parity
value for each bit of data protects data. Conceptually, the parity value is
computed from the data at the same location on each of the other disk units in
the device parity set. When a disk failure occurs, the data on the failing unit can
be reconstructed by using the saved parity value and the values of the bits in the
same locations on the other disk.
Device parity protection is a high-availability function. It allows theIBM Eserver
i5 or iSeries server to continue to operate when a single disk failure has
occurred. The system runs in an exposed mode until the repair operation is
complete and the data is rebuilt. If a failure occurs, correct the problem quickly.
Otherwise, in the unlikely event that another disk fails, you can lose data.
The base disk unit controller in the 9406 Server 520, 550, 570, and 820 does not
support device parity protection. The #5709 RAID Enabler Card supports device
parity protection. In the 9406 595 a #2780 PCI-X Ultra RAID Disk Controller is
required to support the base drives in the #9194 Base PCI-X Expansion Tower.
Internal disk, tape, CD-ROM, DVD-RAM, DVD-ROM storage
5486IntStor.fm
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