Disks have several characteristics, which are either attributes determined by the manufacturer or attributes that are supported by Data ONTAP. Data ONTAP manages disks based on the following characteristics:
Data ONTAP supports the following disk types, depending on the specific storage system, the disk shelves, and the I/O modules installed in the system:
The following table shows what disk type is supported by which storage system, depending on the disk shelf and I/O module installed.
For more information about disk support and capacity, see the System Configuration Guide on the NetApp on the Web (NOW) site at http://now.netapp.com/. When you access the System Configuration Guide, select the Data ONTAP version and storage system to find current information about all aspects of disk and disk shelf support and storage capacity.
When you add a new disk, Data ONTAP reduces the amount of space on that disk available for user data by rounding down. This maintains compatibility across disks from various manufacturers. The available disk space listed by informational commands such as sysconfig is, therefore, less for each disk than its rated capacity (which you use if you specify disk size when creating an aggregate). The available disk space on a disk is rounded down as shown in the following table.
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250-GB disks | ||
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320-GB disks | ||
Disk speed is measured in revolutions per minute (RPM) and directly impacts input/output operations per second (IOPS) per drive as well as response time. Data ONTAP supports the following speeds for FC and ATA disk drives:
For more information about supported disk speeds, see the System Configuration Guide. For information about optimizing performance with 15K RPM FC disk drives, see the Technical Report (TR3285) on the NOWTM site at http://now.netapp.com/.
It is best to create homogenous aggregates with the same disk speed rather than mix drives with different speeds. For example, do not use10K and 15K FC disk drives in the same aggregate. If you plan to upgrade 10K FC disk drives to 15K FC disk drives, use the following process as a guideline:
All new NetApp storage systems use block checksum disks (BCDs), which have a disk format of 520 bytes per sector. If you have an older storage system, it might have zoned checksum disks (ZCDs), which have a disk format of 512 bytes per sector. When you run the setup command, Data ONTAP uses the disk checksum type to determine the checksum type of aggregates that you create. For more information about checksum types, see How Data ONTAP enforces checksum type rules.
Disk addresses are represented in the following format:
HA.disk_id
HA refers to the host adapter (HA) number, which is the slot number on the storage system where the host adapter is attached, as shown in the following examples:
disk_id is a protocol-specific identifier for attached disks. For Fibre Channel-Arbitrated Loop (FC-AL), the disk_id is an integer from 0 to 126. However, Data ONTAP only uses integers from 16 to 125. For SCSI, the disk_id is an integer from 0 to 15.
The disk_id corresponds to the disk shelf number and the bay in which the disk is installed, based on the disk shelf type. This results in a disk drive addressing map, which is typically included in the hardware guide for the disk shelf. The lowest disk_id is always in the far right bay of the first disk shelf. The next higher disk_id is in the next bay to the left, and so on. The following tables show examples of disk drive addressing maps for these disk shelves:
Note
SCSI Enclosure Services (SES) is a program that monitors the disk shelf itself and requires that one or more bays always be occupied for SES to communicate with the storage system. These drives are referred to as SES drives.
The following table illustrates the shelf layout for the DS14 disk shelf. Note that the SES drives are in bay 0 and bay 1, and that the drive bay numbers begin with 16, on shelf ID 1.
The following table illustrates the shelf layout for the FC7, FC8, and FC9 disk shelves. Note that the SES drives are in bay 3 and bay 4, and that the drive bay numbers begin with 0, on shelf ID 0.
The following table illustrates the shelf layout for the R100 and R150 disk shelves. Note that bays 4 through 7 are not shown.
The RAID group disk type determines how the disk will be used in the RAID group. A disk cannot be used until it is configured as one of the following RAID group disk types and assigned to a RAID group.
For more details on RAID group disk types, see Understanding RAID groups.
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Part No. 210-01085_B0
File: 3disk2.htm
Last updated: 01-Dec-2005 16:51:24