HP LeftHand SAN Solutions Support Document Application Notes Multi-Site SAN Performance
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Contents Overview........................................................ 5 Multi-Site SAN.................................................. 6 Performance Tuning Tips.......................................... 6 Performance Test Environment for Realistic Application Benchmarks...... 7 Maximum Performance Metrics (Cache Hit Performance)................ 8 Real-World Application Benchmarks................................. 9 Lefthand Multi-Site San Performance Results........................ 11 Conclusion..................................................... 15 Additional References............................................ 15 3
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Multi-site SAN Performance Overview The Multi-Site SAN from LeftHand Networks simplifies high availability by providing a robust, scalable, and highly available SAN storage solution that is managed as a single storage pool. The Multi-Site SAN allows users to physically split the storage cluster to two geographic locations, providing protection from not only individual storage nodes going offline, but from the failure of an entire rack, building, or site. The Multi-Site SAN also protects data at remote or branch locations with the use of the included Remote Office Solutions Pack. The LeftHand Networks SAN architecture enables aggregating of any number of storage nodes to create storage clusters. Increasing the number of storage nodes used in a cluster increases the total number of disks, processors, controllers, network connections and cache used in the storage cluster, allowing 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 LeftHand Networks Multi-Site SAN were selected to maximize throughput, IOPS, and scalability. 5
Multi-Site SAN The cost-effective Multi-Site SAN provides reliable, always-on data availability. This LeftHand solution comes complete with everything you need to deploy fully functional storage systems in two separate locations managed as a single SAN, ensuring that your data stays online, even during a complete site failure. The Multi-Site SAN is ideal for rolling out a highly available, virtualized IT infrastructure. Non-disruptive performance scalability helps you avoid bottlenecks and expensive controller upgrades. A single, simple management interface for the two distinct sites allows configuration changes on the fly, no downtime. The Multi-Site SAN hardware consists of: 48 15k SAS disk drives (21.6TB), Dual active/active load balanced controllers (per site), 10 GB memory and cache, Eight gigabit network ports and redundant power and cooling. To extend the SAN s high availability capabilities out to remote and branch offices, implement the Remote Office Solution Pack that s included in your SAN. The Remote Office Solution Pack is certified with VMware's Site Recovery Manager, delivering efficient, affordable SAN replication without the purchase of additional hardware. 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. 6
Make sure all switch ports and Ethernet adapters are configured to run at Full-duplex Gigabit speeds. 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: 7
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 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. Maximum Performance Metrics (Cache Hit Performance) 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. 8
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. Microsoft Exchange Jetstress The Jetstress tool that 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. 9
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. 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. Best Practices - Run IOmeter against raw disks to avoid file system cache interference. 10
Lefthand Multi-Site San Performance Results Figure 1 Cache hit random IOPS Figure 2 Cache hit sequential throughput 11
Figure 3 Single Host SQLIOStress IPS Figure 4 Single Host Jetstress IOPS 12
Figure 5 Single Host File Copy Reads Figure 6 Single Host File Copy Writes 13
Figure 7 512 byte Random IOPS Figure 8 64K Sequential Workload - MB/s 14
Conclusion The Multi-Site SAN from LeftHand Networks delivers reliable, scalable and predictable performance for enterprise production environments that require maximum availability and data protection. LeftHand Networks storage clustering allows the resources of multiple storage arrays to be aggregated together with the LeftHand Networks Multi-Site SAN to create a robust high performance storage cluster. The flexibility and power of LeftHand Networks storage clustering paired with the LeftHand SAN product line allow a customer to meet any performance and/or capacity need. Coupled with the Remote Office Solution Pack, Multi-Site SAN users have unprecedented availability and data protection. Additional References Optimizing Storage for Exchange Server 2003 http://www.microsoft.com/ downloads/ details.aspx?familyid=c6084d20-9730-4ffc-805d-b957327604c6&dis playlang=en Using Jetstress to Verify Storage System Performance - http:// technet.microsoft.com/en-us/library/aa996390.aspx Windows Server 2003 Resource Kit Tools (Robocopy) - http:// www.microsoft.com/downloads/ details.aspx?familyid=9d467a69-57ff-4ae7-96ee-b18c4790cffd&displayl ang=en App Note - Building High Performance High Availability IP Storage Networks with SANiQ App Note - Best Practices for Enabling Microsoft Windows with SAN/iQ Iometer Downloads - http://www.iometer.org/doc/downloads.html The Information in this Article applies to SAN/iQ versions 8.0+ Microsoft Windows Server 2000/2003/2008 15
16 *Some of the performance claims represented in this document are extrapolated from benchmark data based on internally accepted performance scaling models used by LeftHand Networks.