60+ production VMs moved to a new SAN backend across a 5-day window, with no maintenance window and zero customer-reported downtime.
5 September 2026 · 2 min read
SECTOR
Virtualization provider
SCALE
60+ production VMs
PLATFORM
VMware vSphere + shared SAN
ENGAGEMENT
Planned migration
VMs migrated live
Total migration window
Customer-reported downtime
Scroll the diagram sideways to see all of it →
Batching by I/O profile is what removed the need for a maintenance window.
Hardware lifecycle set the deadline; the business set the constraint. The SAN controller backing the primary datastore was approaching end of support. All VM storage had to move to a new backend without customer-visible downtime during business hours.
Profile first, migrate second. We assessed the storage layout, identified the VMs with high I/O profiles that needed priority handling, and mapped the snapshot dependencies. Storage vMotion behaviour was then tested under load against a staging subset to validate performance impact thresholds before anything production moved.
The absence of a maintenance window was the real constraint — not the migration itself.
Not a fault. This was a planned migration driven by hardware lifecycle. The engineering challenge was executing it live, with no maintenance window available.
SAN controller approaching end of support, with no maintenance window available.
Profile I/O per VM, validate vMotion under load in staging, then migrate in batches.
60+ VMs moved over 5 days. Old SAN decommissioned on schedule.
Controlled batches, weighted by I/O profile. We ran staged storage vMotion during lower-traffic periods, with high-I/O VMs prioritised into overnight windows. Latency and throughput were monitored continuously through each batch, and datastore integrity and snapshot chain health were verified after every migration.
All 60+ VMs moved with zero customer-reported downtime. The migration completed over a 5-day window and the old SAN was decommissioned on schedule.
Staged, monitored and reversible. We plan storage migrations around your traffic rather than around a Sunday night outage notice.
