ASM 磁盘大小限制

在准备一个测试环境时，发现我的磁盘认出来变小了，实际上是3TB的盘，但是在ASMCA工具里面看到的磁盘大小只有900GB，如下：



实际盘大小，单位为MB：

[uathzdb@root]# bootinfo -s hdisk1
3072000
[uathzdb@root]# bootinfo -s hdisk2
3072000
[uathzdb@root]# bootinfo -s hdisk3
3072000

不管怎么弄还是只能认出900GB，没办法只能开了个SR了，原来才知道ASM磁盘大小是有限制的，最大只能是2TB，不过EXADATA的限制就宽了很多啊。SR的恢复如下：

Understood your concern,You can not add disk more than 2 TB as a asm disk.Please check with your os admin to break the 3 Tb disk in to 1.5 Tb and then use it as a ASM disk.Following are few points to consider,

ASM provides near unlimited capacity for future growth, but does have some storage limits.
For example, ASM has the following limits on the number of disk groups, disks, and files:
1.) 63 disk groups in a storage system
2.) 10,000 ASM disks in a storage system
3.) 1 million files for each disk group

Without any Oracle Exadata Storage, ASM has these storage limits:

1.) 2 terabytes (TB) maximum storage for each ASM disk
2.) 20 petabytes (PB) maximum for the storage system
With all Oracle Exadata Storage, ASM has these storage limits:
3.) 4 PB maximum storage for each ASM disk
4.) 40 exabytes (EB) maximum for the storage system

The maximum size limit of a disk group equals the maximum disk size multiplied by the maximum number of disks in a disk group (10,000).The maximum number of disks across all disk groups is 10,000. The 10,000 disks can be in
one disk group or distributed across a maximum of 63 disk groups. This is a limitation on the number of ASM disks, not necessarily the number of spindles. A storage array could group multiple spindles into a LUN that is used as a single ASM disk. However ASM is currently limited to 2 TB in a single disk unless using Oracle Exadata storage.

File size limits are dependent on the value of the disk group compatibility attributes. ASM supports file sizes greater than 128 TB in any redundancy mode when the COMPATIBLE.RDBMS disk group attribute is set greater than10.1. If COMPATIBLE.RDBMS is set to 10.1, the file size limits are less. For example, with COMPATIBLE.RDBMS equal to 10.1 and the AU size equal to 1 MB, ASM file size limits are:

1.) External redundancy: 16 TB
2.) Normal redundancy: 5.8 TB
3.) High redundancy: 3.9 TB