| US 7,523,286 B2 | ||
| System and method for real-time balancing of user workload across multiple storage systems with shared back end storage | ||
| Swaminathan Ramany, Sunnyvale, Calif. (US); and Vladimir Yakubov, Fremont, Calif. (US) | ||
| Assigned to Network Appliance, Inc., Sunnyvale, Calif. (US) | ||
| Filed on Nov. 19, 2004, as Appl. No. 10/992,893. | ||
| Prior Publication US 2006/0112247 A1, May 25, 2006 | ||
| Int. Cl. G06F 13/00 (2006.01) | ||
| U.S. Cl. 711—170 [710/240; 711/154; 711/165; 718/105] | 30 Claims |

| 1. A method for real-time balancing of workload across a plurality of physical storage systems, comprising:
(a) collecting performance data for each of the plurality of physical storage systems, wherein each physical storage system
shares access to a plurality of storage devices;
(b) computing a set of overall metrics for each of the plurality of physical storage systems, wherein the set of overall metrics
for each physical storage system are calculated over a moving window of time to obtain average values;
(c) determining if any of the physical storage systems exceeds one or more predefined thresholds;
(d) looping back to step (a), in response to determining that none of the physical storage systems are exceeding any of the
one or more thresholds;
(e) selecting a virtual storage system for migration from one of the plurality of physical storage systems to a destination
storage system in response to determining that at least one of the physical storage systems exceeds one or more predefined
thresholds, by
(i) creating a usage table for each virtual storage system associated with each source physical storage system, wherein creating
the usage table further comprises calculating a vfiler ratio (VR), wherein the vfiler ratio is equal to vfiler operations
per second divided by physical storage system operations per second,
(ii) selecting a source physical storage system and a destination physical storage system, and
(iii) selecting the virtual storage system for migration; and
(f) migrating the virtual storage system to the destination storage system, wherein the virtual storage system is accessed
directly on the destination storage system using network resources assigned to the virtual storage system prior to migrating.
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