" Oracle large database systems on AIX / unix Detailed combat " focuses 36: mirroring provides safety in use in the AIX environment Wenping
Or a user problem: On AIX p buy a new hard drive to improve server how to do high-availability capabilities of the system, do not affect the performance of the case.
Obviously, the mirror will increase the use of doubling the AIX system high availability: a damaged disc, when data is not available, use AIX disk mirroring, mirrored logical volumes or normal business operations, this is done automatically in the case where the AIX. system (assumed for database applications), mirroring can be implemented in three ways:
One: do RAID10 / 01 directly on the hard disk to mirror. Of course, this requires the appropriate adapter support is accomplished with a raw device file system or the host database (Oracle, Sybase, etc.) mirror support;
II: AIX operating system using mirroring, RAID1 done on a volume group;
Three: do mirroring at the database level, such as the use sybase database mirroring device, Oracle log groups, in order to achieve a soft mirroring capability.
Clearly, the effect of the first two methods as well, to provide good performance and high availability capabilities, but first need hardware support, meaning that the cost of the upgrade, the second level is implemented in AIX, no need to replace the machine's hardware section.
When to make a mirror level AIX, AIX support to mirror the volume group, you can also make a mirror on the specified logical volume. If the volume group is a logical mirrored individual, the disk number is preferably three or more, to ensure high availability of data. In addition, make a mirror, the mirror must be located at different positions of the hard disk, so that when a piece of image is damaged when the plate members, the disc can continue its mirror image, high availability systems.
In doing mirrored volume group, of course, Pan is also in the number of three or more. For rootvg, then two is enough.
To ensure the volume group, the volume group in AIX something called a volume group descriptor area to maintain information about the volume group, physical volume group will have a hard drive at least the VGDA (volume group descriptor area) is stored the logical structure and use of information on the volume group disk drive, the following relationship exists between the number of hard drives and VGDA:
- A hard drive: The hard disk has two VGDA.
- Two drives: a hard disk has two first VGDA, a second hard drive VGDA.
- Three (or more) hard disk: hard disk each have a VGDA.
quorum volume group, represents the ratio of the volume group VGDA available, must be higher than 51% of the volume group can be used. So, if there are three (or more) hard disk volume group volume group, if a hard disk is damaged, there will be at least 66% of the available VGDA start and use the volume group.
If the volume group only two disks, and must be done mirroring, you can turn off quorum, so even a single hard damage occurs, it does not make the whole volume group to fail. Of course, this is not a good method. Therefore, when the logical volume mirrors, preferably the volume group to have three mirrors, or volume groups (or more) hard disk go to meet the high-availability system.
I hope to be helpful!
Sincerely, I wish you success!
Reproduced in: https: //www.cnblogs.com/dbserver/articles/1694556.html