Logical Drive Sector Size and Migration

This application note deals with a specific application for VTrak M-Class and E-Class in a Windows 2000/WinXP 32-bit OS environment.

In order to achieve the desired RAID online capacity migration, adding 10 disk drives to an existing RAID 5 logical drive you must create your logical drives with 1 KB sectors.
Note: Some database applications may be incompatible with sector sizes larger than 512 bytes.
Before you create a logical drive with a 1 KB sector size, verify that any applications that will access the logical drive can support the 1 KB sector size.

There are two situations in which you create logical drives:
- During disk array creation.
- When adding a logical drive to an existing disk array.

In order to specify the sector size in WebPAM PROe or the CLU you MUST select "Advanced" option for Disk Array creation, please refer to the VTrak M-Class and Vtrak E-Class Product Manual as well as the WebPAM PROe sections.

For detailed directions on how to add drives to your existing array (Online Capacity Expansion), please refer to the VTrak M-Class and Vtrak E-Class Product Manual as well as the WebPAM PROe CLI and CLU sections

For this logical drive size

Select this sector size

Up to 16 TB

4096 bytes (4 KB)

Up to 8 TB

2048 bytes (2 KB)

Up to 4 TB

1024 bytes (1 KB)

Up to 2 TB

512 bytes (512 B)

The above table shows the correlation between Logical Drive size and sector size, as imposed by the Logical Block Addressing limitations of the operating system.

Examples:

Begin with a RAID 5 Logical Drive composed of four 250GB disk drives for a total capacity of 750GB. When you first create the Logical Drive with the default 512 byte sector size you can:
- add five more 250GB disk drives to the same RAID 5 logical drive, for a total capacity of 2TB.
- add ten more 250GB disk drives, but the total capacity will still be only 2TB.

Begin with a RAID 5 Logical Drive composed of four 250GB disk drives for a total capacity of 750GB. When you first create the Logical Drive and you specify a 1 KB sector size you can:
- add five more 250GB disk drives to the same RAID 5 logical drive, for a total capacity of 2TB.
- add ten more 250GB disk drives, for a total capacity of 3.25TB.

Note: If you have an existing Logical Drive with four 250GB disk drives and 512 byte sectors and you expand it by adding ten 250GB disk drives, the result will appear in Windows 2000 as a logical drive of 2TB, plus 1.25TB of unpartitioned space which can be partitioned and formated as a second Logical Drive of 1.25TB.