Dell was migrating its email service from EXL to Microsoft 365 using FastCollect, an application developed by the Archive360 team. The migration created a job for each user to move user data and archived emails from the source SQL Server to the destination SQL Server.

Business Challenges

Per-user migration jobs began stalling partway through the process, putting the broader EXL to O365 timeline at risk.

Jobs entering a sleeping state

Per-user migration jobs were going into a sleeping or transferring state during data migration.

Migration timeouts

Jobs were timing out, stalling the move of user data and archived emails from source to destination SQL Server.

TempDB contention

TempDB running on shared SAN storage was limiting throughput as concurrent migration jobs increased.

Need to scale reliably

The migration needed to support a large number of per-user jobs running concurrently without destabilizing the environment.

Project Objectives

Geopits was brought in to investigate and resolve why per-user migration jobs were entering a sleeping state and timing out during the EXL to O365 migration.

Key Goals:

Identify the root cause of job timeouts and sleeping states
Restore stable migration throughput at scale
Support a growing number of concurrent migration jobs reliably

Solution Provided by Geopits

Geopits traced the sleeping and timeout behavior to TempDB contention and rebuilt the SQL Server configuration around dedicated, sized-for-purpose infrastructure.

TempDB moved to dedicated storage

TempDB was relocated from shared SAN storage to dedicated local NVMe/SSD storage on both cluster nodes, with 2 TB provisioned per node.

TempDB file count optimized

TempDB data files were increased from 4 to 8, aligning with CPU core count recommendations.

Memory allocation increased

Max Server Memory was increased from 122 GB to 185 GB to reduce memory pressure.

Automated statistics maintenance

An automated daily Update Statistics job was implemented for critical large tables, alongside broader SQL Server configuration tuning.

Results & Business Impact

Resolving TempDB contention removed the bottleneck limiting concurrent migration jobs and stabilized the entire EXL to O365 migration.

Capabilities

Before

After

TempDB storage

Shared SAN

Dedicated local NVMe/SSD, 2 TB per node

TempDB data files

8, aligned to CPU core count

Max server memory

122 GB

185 GB

Statistics maintenance

Manual, inconsistent

Automated daily job

Concurrent migration jobs

Failing at 25

Stable at approximately 100

Migration success rate

Jobs timing out and sleeping

99.99%

Key outcomes

Migration resumed at scale

Migration resumed successfully with 25 concurrent jobs, with no transferring or sleeping anomalies observed.

Scaled to 100 concurrent jobs

Concurrent migration jobs were gradually increased to approximately 100, and the environment remained stable throughout the monitoring period.

99.99% success rate

The migration achieved an overall 99.99% success rate, resolving the job timeout and sleeping state issues.

Conclusion

Geopits diagnosed and resolved TempDB contention behind Dell's EXL to O365 migration job failures, relocating TempDB to dedicated NVMe storage and tuning SQL Server configuration to reach a 99.99% success rate at scale.

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