| PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Solaris(TM) Operating System) |
|
Contents
|
| Appendix A General Notes | > A.3 General Points |
Pay attention to the following guidelines when constructing striping configurations.
In order to improve I/O performance with striping, it is necessary to adjust the stripe width and the number of stripe columns depending on the way an application accesses the disk.
If the striping configuration is not appropriate, you cannot gain much performance improvement. And, depending on the way an application accesses the disk, the performance may not improve even after adjusting the stripe width or the number of stripe columns.
Do not make the stripe widths too large.
The sizes of stripe groups and stripe volumes are rounded to the common multiple of stripe width times the number of stripe columns and cylinder size. Therefore, if the stripe width is too large, use of the disk area may be inefficient or a volume with the intended size may be created.
Where possible, connect disks and lower level groups with the same available sizes to the same stripe group.
The available size of the stripe group (available capacity as volumes) equals the available size of the smallest disk or the lower level group connected to the stripe group multiplied by the number of stripe columns and rounded down to the common multiple of stripe width times the number of stripe columns and cylinder size.
When connecting disks or lower level groups with different available sizes to a stripe group, the larger disk or lower level group will only be able to use the capacity of the smaller disk or lower level group. For example, if a 4 GB disk and a 9 GB disk are connected to one stripe group, the 9 GB disk will only be able to use approximately 4 GB. Which means, the available size of stripe group will be approximately 8 GB (4 GB x 2).
Where possible, striping across disks with similar performance specifications is recommended.
When striping disks with different performance specifications such as revolution speed, the performance becomes unbalanced and will depend on the slower disk performance.
Using striping in combination with mirroring is recommended.
In a striping configuration, the risk of losing data from a disk failure increases as more disks are involved compared to a usual disk configuration.
By mirroring stripe groups, both the I/O load balancing and data redundancy can be achieved at the same time.
|
Contents
|