IBM 8000 Series, 7000 Series manual Single disk. RAID 5 arrays require a minimum of three

3ware Escalade ATA RAID Controller Installation Guide

a single disk. RAID 5 arrays require a minimum of three

drives. Configurations consist of at least 3 drives and up to 12 drives.

3ware Disk Array Configuration

Available Drives:
Port 0	- QUANTUM FIREBALLP KX27.3			512 M
Disk Arrays:
Array Unit 1 - 3 drive 64K RAID 5				1.0GB
Port	1	- IBM-	DTLA-387815	512	M
Port	2	- IBM-	Init RAID5 Array Unit	1	M
			DTLA-387815	512
Port	3	- IBM-	DTLA-387815	512	M
			Percentage done : 25%

Create Array Delete Array Maintain Array Rebuild Array

Alt-F1 Help	Previous/Next $ Toggle Hot Spare EnterSelect/Deselect
F6 Restore Initial Values Esc Cancel		F8 Done

Figure 10. BIOS Initialization Screen for RAID 5

Select striping size

For a RAID 0 or RAID 10 configuration select the striping size. Sizes of 64K, 128K, 256K, 512K or 1M are selected using the Stripe Size box shown in Figure 8. RAID 5 only allows a 64K stripe size. RAID 1 does not allow the user to select the striping size.

Select write cache properties

The Escalade ATA RAID Controller gives you a choice of disabling the write cache for your disk arrays. Write cache is used to store data locally on the drive before it is written to the disk, allowing the computer to continue with its next task. Enabling the write cache

3ware Disk Array Configuration Utility

results in the most efficient access times for your computer system. There may be instances when you always want the computer to wait for the drive to write all the data to disk before going on to its next task. For this case, you must disable the write cache. To disable the write cache, select disable from the array’s Write Cache State selection. The default for Write Cache State is enable.

Confirm array configuration

Select the OK button to confirm creating the array or Cancel to reject it. The array is not actually created and no data will be over- written until you have finished making all your changes and select the F8 key.

Note: The current limitation is 2 TB for any physical or logical unit. If you attempt to create an array over 2 TB the BIOS will display the following message: “The amount of disk space available exceeds the maxi- mum allowable capacity. The array capacity will be lim- ited to 2 TB.”

For RAID 5 Arrays

Because of the Read-Modify-Write operations, zeros are first writ- ten to all drives in the array before the array is functional. The screen shown in Figure 10 appears after selecting OK to confirm array creation.

If desired, the write-zeros operation can be aborted by rebooting the system. Once booted to the operating system, the array goes into initialization mode after a delay of up to ten minutes. The advan- tage of doing this is that the RAID 5 can be used immediately, although it will not be fault tolerant until the initialization is com- plete. The disadvantage of doing this is that it will take longer for

32 www.3ware.com www.3ware.com 33