oracle asm alias 文件别名

今天在网上看到一个朋友问:为什么在ASM存储管理的方式下明明只设置了log_archive_dest_1来指定归档的路径，却在ASM下发现了两处归档日志文件？（未开闪回）

我查了一些资料，认为是这样的：
Every file created in ASM gets a system-generated filename, otherwise known as a fully qualified filename (FQFN). The fully qualified filename represents a complete path name in the ASM file system. An example of a fully qualified filename is:
+dgroup2/sample/controlfile/Current.256.541956473
You can use the fully qualified filename to reference (read or retrieve) an ASM file. ASM generates a fully qualified filename upon any request to create a file. A creation request cannot specify a fully qualified filename. Instead, it uses a simpler syntax to specify a file, such as an alias or just a disk group name. ASM then creates the file, placing it in the correct ASM “path” according to file type, and then assigns an appropriate fully qualified filename. If you specify an alias in the creation request, ASM also creates the alias so that it references the fully qualified filename.

最后ls -l 看了下ASM里这两个目录下的归档日志文件后发现，确实就是这种情况：

Oracle不希望我们改这些文件的路径，但我们热衷于做这个，而且ORacle自动产生的文件名不方便人为记忆并管理，估计oracle也意识到了这问题便也有了别名了。