HP LeftHand P4000 - SAN Solutions Supplement

HP LeftHand SAN Solutions
Support Document
Application Notes
NSM 2120-G2 Performance

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© Copyright 2009Hewlett-Packard Development Company, L.P.

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Contents
NSM 2120-G2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Maximum Performance Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Performance Tuning Tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Performance Test Environment for Realistic Application Benchmarks . . . . . . . . . . . . . . . . . . 7
Real-World Application Benchmarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
NSM2120 Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Additional References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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NSM 2120-G2 Performance
Overview
The LeftHand Networks NSM 2120-G2 is an ideal platform to build robust
storage clusters running the LeftHand Networks SAN/iQ®software.
LeftHand’s SAN/iQ software platform delivers enterprise-class SAN
functionality on industry standard hardware. This document provides an
overview of the performance characteristics your applications can rely on with
the LeftHand Networks NSM 2120-G2.
The LeftHand Networks SAN
architecture enables the aggregation
of any number of storage nodes to
create storage clusters. Increasing the
number of storage nodes in a cluster
increases the total number of disks,
processors, controllers, network connections and cache used in the storage
cluster, which allows for performance to scale along with capacity.
In addition, SAN/iQ Network RAID dynamically load balances data across the
storage clusters and eliminates bottlenecks as the cluster grows. This
dramatically increases data availability since data is now striped and
mirrored across multiple storage nodes. The disks, processors, controllers,
network connections and caches in the NSM 2120-G2 were selected to
maximize throughput, IOPS, and scalability.
NSM 2120-G2
The LeftHand Networks NSM 2120-G2 is an enterprise class storage node
built on industry-standard Intel chipsets. The storage node can utilize either
Serial Attached SCSI (SAS) or Serial ATA II (SATA) disk drives. The solution
is available in multiple disk configurations yielding between 1.8 to 12.0
Terabytes (TB) of raw storage capacity. The LeftHand Networks NSM

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2120-G2 provides enterprise-class reliability, high availability and
performance. Specific product highlights include: Twelve hot swappable disk
drives, dual NIC connectivity with automatic failover, dual power supplies,
robust power and cooling, and battery-backed write cache.
Maximum Performance Metrics
The maximum performance metrics data is used to show maximum
performance limits of the SAN in an optimal scenario. While these numbers
are often used as a basis of comparison between different storage vendors,
they aren't representative of the workload typically found in production
environments. The type of workload run against the SAN can dramatically
affect performance numbers. The maximum performance metrics should be
used for comparison against other SAN vendors rather than as a guideline for
your specific needs. When sizing for your specific environment, LeftHand
Networks advises using a benchmark that closely resembles your own data
requirements.
Performance Tuning Tips
SAN performance can be negatively impacted if the SAN is not configured
properly. The following guidelines will help maximize the performance of the
LeftHand Networks SAN.
Network Best Practices
•Use Gigabit Ethernet switching infrastructure.
•Dedicate a separate IP subnet/VLAN for your iSCSI SAN.
•Use a secondary Gigabit Ethernet NIC in servers attached to the Ethernet
storage subnet for high availability and performance.
•If possible attach all modules and application servers to the same Gigabit
switches for the storage networking.
•Make sure all switch ports and Ethernet adapters are configured to run at
Full-duplex Gigabit speeds.

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Disk Formatting Best Practices
•Use the default block size, or allocation unit size, unless a particular
application specifies an alternate size. Microsoft Exchange should be on
volumes formatted with a block size of 4096 bytes.
•Partitions should be created starting at sector 128 to align the offset to
64KB using Diskpar or Diskpart.
Storage Node Configuration Best Practices
•Bond networks interfaces for network redundancy and more bandwidth
using Adaptive Load Balancing (ALB).
•Use RAID level 5 or 10 for disk redundancy within storage modules.
•Enable SAN/iQ iSCSI Load Balancing on authentication groups for
Windows servers
•Install the DSM software driver to enable fault-tolerant paths to the SAN
modules while also increasing available bandwidth to the SAN for
maximum performance
Performance Test Environment for Realistic Application Benchmarks
Performance data was gathered using enterprise class servers with the
following attributes:
•2.8GHz dual core Intel Xeon processor
•4 gigabytes of RAM
•Dual gigabit Ethernet network adapters (bonded using balance ALB)
•All equipment connected to the same gigabit Ethernet switch
The iSCSI SAN configurations included a dedicated group of three storage
nodes comprised of:
•Single management group with a single cluster including all
storage modules
•Storage modules were configured in either RAID 5 with volumes further
protected by SAN/iQ Network RAID Level-2 (2-way Replication).
•iSCSI sessions were load balanced across the clusters using SAN/iQ iSCSI
Load Balancing

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The LeftHand Networks SAN is designed to work on your existing Ethernet
infrastructure. Segmenting the storage network from your corporate network
is recommended, and boosts overall performance of the solution. For
performance testing, the SAN network was isolated to a single broadcast
domain (subnet) and had dedicated NICs for the storage traffic. A single 24
port Gigabit switch was used for all tests.
All disk volumes were configured using the Microsoft iSCSI Software Initiator
Version 2.0.4. Volumes were mounted using the Windows Logical Disk
Manager and formatted with NTFS using the default allocation unit size.
Real-World Application Benchmarks
All of the following benchmarks were designed to help characterize the actual
performance users can expect in similar production environments. Each
benchmark measures different storage characteristics. Standard SQL server
and Exchange benchmarks illustrate the expected performance in those
application environments. Simple file copies show throughput in megabytes
per second (MB/sec) and IOmeter simulates IOPS (inputs/outputs per second)
and throughput.
Microsoft SQLIOStress
The SQLIOStress utility was written and is maintained by the Microsoft SQL
Server Escalation staff. Designed to help detect possible I/O path problems
that would lead to Microsoft SQL Server data corruption or loss, it emulates
different SQL server database versions and types and reports on some basic
benchmarks. At a minimum it runs 5 iterations. Only the third and fourth
iterations should be used for comparing performance according to the
SQLIOStress tool documentation. For this document the 4th iteration will be
used. The SQLIOStress test runs from only a single host and typically
becomes CPU bound. The tool is not capable of scaling at the same rate as the
SAN. Some scaling is achieved on a single host due to the lower latency in
the SAN.
Best Practice - Keep the data files and logs for SQL databases on
separate volumes.

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Microsoft Exchange Jetstress
The Jetstress tool allows administrators to verify the performance and
stability of the disk subsystem before putting their Exchange server into a
production environment. It reports back to the administrator with an html
document that contains results and a PASS or FAIL for the overall test. A
PASS or FAIL is strictly based on specific test results not exceeding Microsoft
specified limits. Disk Latency is the primary metric used by Jetstress for
PASS / FAIL criteria. The values to pass are the log avg. disk sec/write,
database page fault stalls, and database avg. disk sec/read. Log average
latency should be below 10ms, database page fault stalls should always be 0,
and database average read latency should be less than 20ms. LeftHand
Networks uses an automated command line version of Jetstress that will
increase threads until the test no longer passes and records the IOPS of the
last passing run. The highest IOPS achieved while still passing is the value
reported in this paper.
Best Practice – Keep the email database files and log files on
separate volumes.
File Copy Using Robust File Copy
The file copy test is a straight-forward Windows file copy. Using robocopy.exe a
file copy of one hundred 100MB files is done from direct attached storage
(DAS) in the server to a volume on the SAN. For this test a simple
measurement of megabytes per second is taken. Robocopy (Robust File Copy)
is included in the Windows resource kit. While individual file copy speeds are
limited by the nature of low queue depth disk operations, the architecture of a
LeftHand Networks SAN solution is capable of handling multiple file copy
jobs simultaneously without degrading performance. This is represented by
the “Concurrent Jobs” set of data.
Best Practice - When copying from DAS to the iSCSI SAN remember the file
copy cannot go any faster than the DAS disk. Make sure the disk that the
source files are on is the fastest disk available to you otherwise it might be
limiting the file copy speed. Running multiple file copies at a time will
increase the aggregate performance.
IOmeter
IOmeter is an I/O subsystem measurement and characterization tool. IOmeter
is a good tool for simulating loads of different I/O sizes to demonstrate a
system’s IOPS and throughput capabilities. These configurations are designed
to show typical speeds as opposed to the maximum values.

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Best Practices - Run IOmeter against raw disks to avoid file system
cache interference.
NSM2120 Performance Results
Figure 1: Cache hit random IOPS
Figure 2: Cache hit sequential throughput