Browse Prior Art Database

A process for piggy-backed mirroring of NAS state

IP.com Disclosure Number: IPCOM000015288D
Original Publication Date: 2002-Apr-19
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Abstract

Disclosed is a process for piggy-backing mirroring of NAS State. When executing on top of a mirrored storage system, data describing the state of the NAS device is mirrored using the data mirroring technique used for the storage system.

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A process for piggy-backed mirroring of NAS state

Disclosed is a process for piggy-backing mirroring of NAS State. When executing on top of a mirrored storage system, data describing the state of the NAS device is mirrored using the data mirroring technique used for the storage system.

Current high-end storage devices provide mechanisms for synchronous, real-time mirroring of data from one storage device to another. Each 'write' operation to a source device is transmitted to a target device and acknowledgement received before the operation is committed on the source device. This prior art ensures that the target storage device remains synchronized with the local devices, and serves to preserve customer data.

Network Attached Storage (NAS) devices are attached to storage devices and provide a file abstraction for those devices -- that is, they allow client devices to access the storage using common, standard file protocols such as NFS and CIFS.

The NAS devices themselves will have configured state orthogonal to the customer data. Examples include administrator IDs and passwords, pointers to the roots of customer data and user configuration for the file system. To achieve replication of the NAS (as opposed only to the customer data), this data must also be transmitted to the replica and acquired there.

Depending on where this information is stored (on the customer data or on a separate storage device), it might or might not be replicated by the storage's replication technology. However, even if automatically replicated, to enable a hot switchover, replication is not sufficient: the data must also be acquired by the remote system.

The process described below ensures consistency of the target NAS and allows an immediate hot switchover.

In the preferred embodiment, all NAS state is stored on customer storage, and we assume that the customer sto...