Dell EqualLogic Best Practices Series Integrating the Dell EqualLogic FS7500 into an Existing SAN A Dell Technical Whitepaper Storage Infrastructure and Solutions Engineering Dell Product Group February 2012
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Table of Contents 1 2 Introduction ........................................................................................................................................................ 1 1.1 Audience ...................................................................................................................................................... 1 1.2 Terminology .......................................................................................................................................
Acknowledgements This whitepaper was produced by the PG Storage Infrastructure and Solutions team between January 2011 and August 2011 at the Dell Labs facility in Round Rock, Texas.
1 Introduction The Dell™ EqualLogic™ FS7500 adds scale-out unified Network Attached Storage (NAS) capabilities to EqualLogic PS Series iSCSI SANs so you can easily enable and manage iSCSI, CIFS, and NFS access from a single management console. The EqualLogic FS7500 incorporates the Dell Fluid File System (FluidFS), which is designed to optimize file access performance and hardware utilization while eliminating capacity constraints.
1.2 Terminology The following terms are used throughout this document. Block I/O Commonly used to describe how an application on a host server accesses data on a local or SAN connected storage system. CIFS Common Internet File System; typically used by Windows clients to access NAS. File I/O Commonly used to describe application or client access to a NFS mount point or CIFS share. Group A PS Series group consists of one or more PS Series arrays connected to an IP network.
2 Dell EqualLogic FS7500 The FS7500 is a dual active/active architecture that consists of a redundant pair of appliance-like controller nodes with a backup power supply. The large onboard cache gives the EqualLogic FS7500 the ability to scale performance. Each system provides 48GB of RAM (24GB in each controller node) that is used for the operating system and the mirrored, battery protected cache memory.
By adding more arrays to the storage pool, the EqualLogic SAN can be scaled out for capacity and performance. NAS volumes and file systems can also be expanded without interruption or downtime. With support for CIFS connectivity from Windows systems and NFS connectivity from UNIX/Linux systems, the FS7500 and PS Series arrays represent a unified and scalable storage solution.
3 Test topology and architecture To study the performance impact of integrating a FS7500 into an existing EqualLogic SAN environment, we needed to generate a workload of both block and file I/O. We chose to use the open-source I/O workload generation tool Vdbench, which is available for download on SourceForge.net. Vdbench requires a JAVA runtime environment, so we also installed the Sun (Oracle) JRE version 6u24 on each client. For clients, we configured four VMware® ESX 4.1 servers.
ports. While this is usually not a recommended best practice for production networks (due to scalability limits), it provided the connectivity we needed for this test environment. On our SAN network, we configured jumbo frames (MTU 9000). This is established best practice for EqualLogic PS Series iSCSI SANs and is also required for the FS7500 SAN and interconnect network ports (which share the same switches with the SAN).
4 Test methodology We selected Vdbench for its ability to be controlled by a script and parameter file. For the block I/O testing, we configured Vdbench to read and write from RAW disks without a file system. For our block clients we used a working file size of 8GB to minimize the effect of client-side caching in the VM. For the file I/O tests, we initially ran tests against both CIFS and NFS mount points.
5 Test results and analysis For the combined block and file tests, we observed (see Figure 2) that IOPS increased as additional clients were added. In the three and four array configurations, performance eventually started to level off as the pool reached maximum I/O capacity. Adding an additional array to the mix allowed the same number of clients to gain additional performance and also to scale further before starting to level off again.
The caching effect of the FS7500 is also evident when looking at Figure 4, where we see that file I/O clients have a slight performance advantage over the block clients. Furthermore, when we examined the data from SAN HQ, it showed that the total number of I/Os actually completed by the storage system for NFS clients was slightly less than the total number of I/Os from all block clients, again indicating the beneficial effects of caching on the FS7500 system.
Figure 4: 6-Array Separated Pool, Block and File I/O Comparison Since additional IOPS capacity was made available to the NAS volumes (doubling the number of physical disk spindles from three to six arrays) we observed that the NAS volume performance increased, but at the same time those volumes now competed for resources with the volumes belonging to the block clients causing the slight decrease in the block performance.
6 Planning and design considerations 6.1 Network ports Each FS7500 controller contains a total of thirteen 1 Gigabit Ethernet ports that need to be connected for optimal performance. A total of 26 network ports are required for each controller pair. Established best practices for EqualLogic SANs recommend that the LAN and SAN be separated, and more specifically, that the SAN is physically isolated from the LAN.
• • For Adaptive Load Balancing (ALB), four IP addresses are required for each NAS node. For example, in a two-node NAS service, eight NAS service IP addresses are required. For LACP, one IP address is required for each NAS node. You need only one IP address for each node because the four client network interfaces are bonded together. For example, in a two-node NAS service, only two NAS service IP addresses are needed. On the SAN, each NAS node requires four IP addresses for the iSCSI interfaces.
workload, then the performance of existing block workloads may be affected as the storage system is forced to share resources between them. 6.4 Volume configuration The FS7500 is able to use the entire capacity of a pool and can support files up to 4TB in size. During configuration of the FS7500, the administrator is allowed to choose the pool that the NAS reserve will be created in.
workloads from attached hosts and in some cases may indicate the need for additional disk I/O capacity (i.e., the more physical disk spindles) to satisfy performance needs. Latency is also an important factor that affects the response time of applications. Higher latencies may be an indicator of slower response times for the attached hosts and applications running on them. However it is also expected that larger block sizes, such as from backup and restore, may result in slightly higher latencies.
7 Summary The Dell EqualLogic FS7500 can be deployed as part of a new installation or into an existing EqualLogic PS Series iSCSI SAN. When deploying into an existing SAN, administrators should monitor the existing SAN to understand the availability of not only data storage capacity, but also of I/O capacity. The data presented in this paper can then be used to help determine if there is a need for additional storage arrays and to help guide the deployment of the FS7500.
Appendix A Vdbench scripts Vdbench script used for block client: Example 1 – Vdbench script used for block client * 100% random 8K, 70% read block I/O test. * hd=default sd=default,size=8g,threads=8 sd=sd1,lun=/dev/sdb,openflags=o_direct o_sync wd=default rd=rd1,sd=sd*,forseekpct=100,rdpct=70,xfersize=8k,elapsed=600,interval=30,i orate=max,openflags=o_direct o_sync Vdbench script used for NFS file client: Note: The “anchor” directory must be unique for each node.
Related publications The following Dell publications are referenced in this document or are recommended sources for additional information. Dell EqualLogic PS Series iSCSI SAN http://www.dell.com/equallogic Dell EqualLogic FS7500 Unified Storage Solution http://www.dell.com/fs7500 Dell EqualLogic Configuration Guide http://www.equallogic.com/resourcecenter/assetview.aspx?id=9831 PS Series Group Administration Online Help http://psonlinehelp.equallogic.com/V5.1/groupmanager.
THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND.
