< Previous  | TOC | Index | Next  >

Volume availability

MVS guarantees the availability of some volumes even when others are unavailable. This allows you to mount a multi-volume file system even if one or more component dataonly volumes are missing.

The volumes are separated by whether metadata is allowed on the volume. An
I/O error on a dataonly volume does not affect access to any other volumes. All VxFS operations that do not access the missing dataonly volume function normally, including:

• Mounting the multi-volume file system, regardless if the file system is read-only or read/write.
• Kernel operations.
• Performing a fsck replay. Logged writes are converted to normal writes if the corresponding volume is dataonly.
• Performing a full fsck.
• Using all other commands that do not access data on a missing volume.

Some operations that could fail if a dataonly volume is missing include:

• Reading or writing file data if the file's data extents were allocated from the missing dataonly volume.
• Using the vxdump command.

Volume availability is supported only on a file system with disk layout Version 7 or later.

  Note   Do not mount a multi-volume system with the ioerror=disable or ioerror=wdisable mount options if the volumes have different availability properties. Symantec recommends the ioerror=mdisable mount option for cluster mounts and ioerror=mwdisable for local mounts.