Notes On Configuring Hard Disk Drive; Creating Striping Array - NEC Express5800 Series Installation Manual

Chapter 1 Installing Operating System

2.4.3 Notes on configuring hard disk drive

If ftdiskadm is used to configure duplication of hard disk drive, Fast Resync feature is enabled by default. This
feature shortens the recovery time of partitions in the hard disk drives when the partitions are isolated from
redundant configuration. Upon recovery, only refreshed data from the running hard disk drive is copied onto the
disk that is isolated from the redundant configuration. If this feature is disabled, all the data is copied onto the
hard disk drive. Therefore, enabling the feature can shorten the time required for recovery.
Fast Resync will not work when the hard disk drive is replaced with new one.

2.4.4 Creating Striping Array

Striping array (RAID 0) is a RAID device that distributes I/O requests issued to striping array to each member.
This feature improves the I/O capacity and data writing/reading speed on striping array. Available disk capacity
on striping array is the total of all members, which is different from RAID1 device in redundant configuration.
You must prepare individual hard disk drives for the members of striping array to improve I/O capacity.
When you configure striping array only, the whole array will be unavailable and the fault tolerance becomes low
if a failure occurs on any of the members. However, you can configure the devices that have both fault tolerance
and I/O capacity (called "RAID1+0 device" in ftdiskadm) by configuring the member of the array with RAID1
devices.
Use ftdiskadm command to create striping array.
The following procedure is an example of configuring striping array using RAID1 device md4 in Slots 2 and 10
and RAID1 device md6 in Slots 3 and 11.
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Important The system may not operate properly when this feature is disabled. Always enable
this feature.
•
You must perform this operation as a root user.
Important
•
You must add 4 or more hard disk drives to utilize the feature of striping array
when you create the array using ftdiskadm.
•
When you create striping array using ftdiskadm, you must make backup copy of
data because the data written on the existing RAID1 device will be erased.
•
It is recommended to use RAID1 devices of the same capacity to be included in
striping array to maximize the feature.
Express5800/R320c-E4, R320c-M4 Installation Guide (Linux)
2. Setting up Red Hat Enterprise Linux 6 Server