Read only access to replication target file systems

Replication and Disaster Recovery Administration Guide for Hitachi NAS Platform

Version
15.1.x
Audience
anonymous
Part Number
MK-92HNAS009-29

Read only access to replication target file systems is possible using NFS, SMB, FTP and NDMP protocols. Previously, only object replication could access and update target file systems. Any manual or client-based attempt to access a replicated filesystem required that the filesystem be changed to a read-write file system first, preventing the file system from being a replication target. Read only access by clients is possible without any adverse effect on file systems.

When using read only access, files and directories on a replication target:

  • Are read only.
  • Match the most recent completed replication.
  • Are updated as soon as a new replication completes.
  • Are unavailable until the first completed replication. The file system can be accessed while replications are active, however there must first be an initial replication to the target to provide a valid file system to clients.

Note the following changes from normal filesystem behavior when using read only access:

  • NFS locks have no effect and are ignored.
  • SMB Oplocks are not issued.
  • SMB3 transparent failover is not available.
  • When virus scanning is underway, unverified files may be re-scanned.

Shares and exports with read-only access

Using shares and exports with read-only access can cause a transfer to fail at the disaster recovery site if a shared name is in use on the replication target, therefore:

  • Names must be defined so transfers work.
  • Incoming shares and exports can overlap existing ones and be renamed.