Reliability, Availability, And Serviceability; Dynamic Load Balance; High Reliability; Spare Disks - Hitachi AMS 2100 Hardware Manual

Reliability, availability, and serviceability

Dynamic load balance

When connecting two or more hosts, the automatic load adjustment
function operates between the Control Units supported by the "Dynamic
Load Balance Controller." Therefore, it is not necessary to take into
consideration which controller the hosts are connected to.

High reliability

The AMS 2100/2300 array controller increases data reliability by adding
original 8 byte data assurance codes to data from a host computer. It
automatically generates the assurance codes across the data bus in the
control unit assigned to the disk drive, and then writes them to the disk
drive along with the data. In addition, it automatically checks the codes
when reading the data. This significantly enhances data reliability in the
data distribution/concentration controller that is assigned to the disk array

Spare disks

An AMS 2100 can include up to 15 spare disks per array. An AMS 2300 can
include up to 30 spare disks per array. The AMS 2100/2300 arrays monitor
the disk drives for potential failure. The data copy operation can be
automatically performed in the background. before a failure actually occurs.
In addition, the redundancy of the dynamic sparing feature enables the
spare disk to be replaced while the system is running (excluding RAID 0
configuration), thereby increasing the reliability of the array even more. The
data recovery to the new disk drive can be performed in running on the
system.
To maintain system reliability, HDS recommends that you include at least
one spare disk drive for each 15 disk drives in an array with SATA disk
drives.

Replacing an active failed disk drive

The AMS 2100/2300 array includes on online data recovery function that
enables users to replace, or "hot swap," a failed active disk drive with a
spare drive while the array is running. Data on the failed disk is recovered
and copied to the new disk drive while the array is running and performing
other functions at the same time.

Redundant power supplies

The AMS 2100/2300 array includes two identical power supplies running in
parallel. If either of these power supplies fails, the other can provide
sufficient power to the system by itself. The array is designed to allow a
failed power supply to be replaced (hot swapped) while the array is running.
The array monitors the power supplies for correct operation and provides an
alert to the Navigator 2 storage management software if the voltages
provided by the power supplies do not meet the system specifications.
Introduction
Hitachi AMS 2100/2300 Storage System Hardware Guide
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