Emc IP Holding Company LLC

Dell Products Inc.

Emc Corporation

Amit Dharmadhikari

Ajay Potnis

Adnan Sahin

Kiran B Halwai

Miles Aram DeForest

Maneesh Singhal

Dixit Patel

Rashmi Shashidhar

Bharadwaj R Sathavalli

Shampavman Chenjeri Gururajarao

Vijay Srinivasan

Sairam Iyer

Rahul Bhagwat

Pavan Ym

A storage node that maintains a replica of a logical volume for use in response to a failover trigger includes a data node with volatile memory in which a filesystem and its metadata and a VDM and its metadata associated with the replica are maintained prior to the failover trigger. The storage node also includes a SAN node in which data associated with the replica is maintained. The data is maintained in a RW (read-write) state by the SAN node prior to the failover trigger. However, the replica is presented in a RO (read-only) state by the storage node prior to the failover trigger. The storage node changes the in-memory state of the filesystem and VDM to RW responsive to the failover trigger. Because the filesystem and its metadata and VDM and its metadata are already in memory and the data is in a RW state in block storage the failover is completed relatively quickly.

Reducing failover time between data nodes

Snaps are distributed among data nodes for load balancing and overload avoidance. A snap is initially associated with a first VNAS server on a first data node that hosts the primary volume being snapped. A second data node is selected based on loading. The second data node may be in the same or a different cluster. A second VNAS server is instantiated on the second data node. The snap is then mounted on the second VNAS server. The second VNAS server may be configured as the target for all reads to the snap. If the second data node is in a different cluster than the snap may be copied or moved from a first SAN node to a second SAN node. Multiple copies of snaps may be distributed, and individual snaps and copies may be associated with different SLOs.

Distribution of snaps for load balancing data node clusters

A first Software Defined Network Attached Storage (SDNAS) process on a first storage system forwards snapshots of a file system provided by the first storage system to a second SDNAS process on a second storage system. The snapshots are forwarded by the first SDNAS process on an Internet Protocol (IP) network, to enable the first and second SDNAS processes to maintain redundant access to data of the file system without requiring the first storage system and second storage system to be interoperable. The initial snapshot includes a full version of the file system and subsequent snapshots include changed portions of the file system. Where the snapshot identifies changed portions at the extent level of granularity, the first SDNAS process subdivides the extents into sub-blocks, and only transmits changed sub-blocks of the extents on the IP network.

File system replication between software defined network attached storage processes using file system snapshots

A method for defining local failover within a storage system using storage group containers includes creating a plurality set of storage groups from physical storage resources of a storage array of the storage system, and creating a masking view identifying a first subset of the storage groups and specifying that Thin Logical Units (TLUs) in the first subset of storage groups are visible only to a primary Software Defined Network Attached Storage (SDNAS) process executing on the storage system and to a backup SDNAS process executing on the storage system. The first set of storage groups includes a Virtual Data Mover (VDM) configuration/root TLU and all user data TLUs used by the primary SDNAS process to thereby enable the set of storage groups used by the SDNAS to be used as a container for local failover.

Method and apparatus for defining local failure using storage group containers

A storage system includes a storage array having physical storage resources, a Software Defined Network Attached Storage (SDNAS) process running in an emulation on the storage system, a user file system having user file system data stored in the storage array that is accessed by the SDNAS process via a first Thin Logical Unit (TLU) storage volume mounted on an emulation operating system, a snapshot copy of the user file system stored in the storage array, and control logic. In some embodiments, the control logic is configured to associate a logical view of the snapshot copy of the user file system to a second TLU, mount the second TLU on the emulation operating system as a snapshot copy file system, and replay pending transactions and sub-transactions of the user file system on the snapshot copy file system to bring the snapshot copy file system to a stable state.

Method and apparatus for mounting and unmounting a stable snapshot copy of a user file system

Disaster recovery is provided for Software Defined Network Attached Storage where the data backup is implemented synchronous data replication. A synchronous replication remote data facility is created between a primary storage array and a backup storage array. User filesystems being handled by a virtual data mover (VDM) and a configuration filesystem describing the location of the user filesystems on the primary storage array are replicated on the remote data facility to the backup storage array. Individual filesystems, individual VDMs, or groups of VDMs may be selectively failed over from the primary storage array to the backup storage array.

Disaster recovery for software defined network attached storage using storage array synchronous data replication

A file server architecture decouples logical storage from physical storage and provides proactive detection and containment of faults, errors, and corruptions in a file system, in order to enable in place (online) and non-intrusive recovery. The file system is built upon a thinly provisioned logical volume, and there are stored three copies of the metadata defining the logical volume in order to provide quick, deterministic, and reliable recovery from a faulted system. A first copy of the metadata is distributed among all of the slices of physical storage allocated to the logical volume. A second copy of the metadata is stored in a root slice of the logical volume. A third copy of the metadata is stored separate from the slices of physical storage allocated to the logical volume.

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Pune, India

Amit Dharmadhikari