Capacity Management for SAN

1. Metron
Capacity Management
for SAN Attached Storage
Warning: Low Disk Space

2. Metron-Athene
• Established 1986
• Stable ownership
• Consistent Focus on CM
• Industry Leadership
www.metron-athene.com

3. Athene
z/OS, HP-UX, AIX, Solaris, Linux
Data Source
Acquire Framework DB/Application
Virtual Server Custom
Control Center
Capacity Database

4. Objectives
• Trends in storage technology.
• Define two distinct aspects of storage capacity.
• Examine key areas related to capacity management of SAN
attached storage.
• Equate with business value.
• Show how tools like Athene can help you achieve your goals.
• Provide ideas about how to proceed with improving storage
capacity management processes in your environment.

5. Trends
• Solid state devices
• Cloud storage
• Embedded storage (e.g. Exadata, vBlock)
• Big data (e.g. Hadoop)
• Tiered storage
• Primary de-duplication
• FCoE, 16 Gbps Fiber, and 10 Gbps Ethernet

6. Two Distinct Aspects of Storage Capacity
Disk Performance Capacity
Response, IOPs
Disk Space Capacity
Bytes

7. Space Capacity – Growth (measureable)
Changing demands for storage – Slope of line

8. Space Capacity - History
Growth can result in increasing cost and complexity

9. Space Capacity – Growth and Cost Factors
Growth
• Business as usual (Trend)
• Acquisitions
• New applications and projects
Costs
• Equipment, including power
• Resource management, including people
• Storage use by application (Billable Customers)

10. Space Capacity – Storage as a Service
How much are customers consuming?
Don’t forget
about the IT
department
and other
insiders!

11. Space Capacity – Tiered Service Model
Define what tiers are (platinum, gold, silver, etc…)
Rates should be
adjusted on a
frequent basis.
Estimate growth
versus storage cost
declines.
Billing is an
effective way to
create
accountability.

12. Space Capacity – Management Support
Effective storage management happens with a bridge to
business results, and building that bridge begins with a solid
foundation. Show business value to be self evident.

13. Space Capacity – Business View
With management backing, important processes can be implemented
Business IT
• Capacity budgeting and
inventory management
• Mandatory storage
request process
• Storage mapping to
determine ownership
• Chargeback of some form
• Define executive reporting
requirements
Once the bridge is built reporting information can flow freely

14. Space Capacity – Who is Responsible
Managing storage capacity requires work.
Storage administrators typically have limited time and
higher priorities in their complex environments.

15. Space Capacity – Over and Under Provisioning
Administrators may have no choice but to over
allocate which results in low utilization.
It is important to define
exactly what ‘Utilization’ is
for your storage.
Many factors determine
what ‘Right Sized’ means
for each system.
But, running out of space
means only one thing to all.

16. Space Capacity – Doing the Technical Work
After roles and responsibilities are assigned and business
requirements are complete, technical solutions can be implemented
to optimize storage space management, including databases.
Trending, forecasting, and exceptions.

17. Space Capacity – Different Viewpoints
Business, Application, Host, Storage Array, Billing Tier
If billing for storage ensure transparency with detail reports

18. Space Capacity – Virtual Environments and Clusters
Managing storage in clustered and/or virtual environment can be challenging
because it is shared among all hosts and virtual machines running on it.
• Manage capacity at a high level
• Account for storage use at a low
level, e.g. VM or DB
• If billing be cautious of different
tiers being allocated to the same
cluster.
• Don’t forget about overhead
Overcommit with thin provisioning

19. Space Capacity – Storage Virtualization
Pooling physical storage from multiple sources into logical groupings
• Simplifies Administration
• Can be a centralized source for
collecting data
• If using as a data source beware
of double counting with backend
• Don’t forget about overhead for
replication
Wide variety of techniques for virtualizing storage, be aware of
the implications for data collection and reporting

20. Space Capacity – Best Practices
Find dark and hidden storage, where it has been
allocated and never used, or plugged into a different box.
Use thin provisioning and de-duplication
where possible.
Include data retention policies for
storage space management.
Account for overhead from
RAID, replication, file systems, etc…
Understand the value of data in deciding where to put
it, how to protect it, and how long to keep it.

21. Space Capacity – Best Practices
Understand the limitations of linear regression when trending
and forecasting data. Use statistics like R^2 to confirm.
Be sure to account for all
variables when ‘Right Sizing’!
Include directory and file level
reporting for file servers if possible.

22. Performance Capacity – Response Impacts
SAN or storage array performance problems can have serious
impacts over a long duration, and be difficult to identify.

23. Performance Capacity – Metrics
Understand the limitations of certain metrics
• Measured response is the best metric
for identifying trouble.
• Host utilization only shows busy time,
it doesn’t give capacity for SAN.
• Physical IOPs is an important
measure of throughput, all disks have
their limitation.
• Queue Length is a good indicator that
a limitation has been reached
somewhere.

24. Performance Capacity – Metric Thresholds
Many times critical host disk metrics are not
breached during impactful events.
Consider using
Statistical
Process Control
Are these potential problems having a real impact?

25. Performance Capacity – Metric Thresholds (Host)
Other times certain metrics like utilization are indicating
impactful events, but ample capacity is still available.

26. Performance Capacity – Metric Thresholds (Host)
Queue lengths from the previous utilization indicate that it may
not currently be impacting response, but headroom is unknown.

27. Performance Capacity – Metric Thresholds (Host)
The high utilization can be seen generating large amounts
of I/O in this chart.

28. Performance Capacity – Architecture (Array)
• Front End Processors
• Shared Cache
• Back End Processors
• Disk Storage

29. Performance Capacity – Metric Thresholds (Array)
Front end processors are typically the first to bottleneck

30. Performance Capacity – Metric Thresholds (Array)
Impact of utilization on response for a single processor
Curves based on simple queuing with normal distribution

31. Performance Capacity – Component Breakdown
Service time versus response time – different metrics

32. Performance Capacity – Workload Profiles
I/O profile has a big impact on performance. Be sure to
include it when comparing applications.
Test with tools like Iometer, IOzone, Bonnie, etc…

33. Performance Capacity – Best Practices

34. Performance Capacity – Best Practices
Trending, forecasting, and exceptions with Athene

35. Performance Capacity – Best Practices
• Choose service levels and establish baselines.
• Use available data sources, vendor utilities, etc…
• Consolidate reporting tools and data. (Athene)

36. Storage Capacity – Final Thoughts
• Talk with storage team about current state of reporting and fill in the gaps.
• Fabric and network utilization might be in scope.
• Set priorities for where to spend time and effort.
• Simplify where possible.
• Work to establish formal naming conventions where needed.
• Tools - without knowledge, experience, and commitment won’t help.

37. Storage Capacity – Thank you for attending
Capacity Management
for SAN Attached Storage
Dale Feiste
Metron-Athene Inc.
dale@metron-athene.com