Microsoft Diskspd (Part II): Server Storage I/O Benchmark Tools

server storage I/O trends

This is part-two of a two-part post pertaining Microsoft Diskspd.that is also part of a broader series focused on server storage I/O benchmarking, performance, capacity planning, tools and related technologies. You can view part-one of this post here, along with companion links here.

Microsoft Diskspd StorageIO lab test drive

Server and StorageIO lab

Talking about tools and technologies is one thing, installing as well as trying them is the next step for gaining experience so how about some quick hands-on time with Microsoft Diskspd (download your copy here).

The following commands all specify an I/O size of 8Kbytes doing I/O to a 45GByte file called diskspd.dat located on the F: drive. Note that a 45GByte file is on the small size for general performance testing, however it was used for simplicity in this example. Ideally a larger target storage area (file, partition, device) would be used, otoh, if your application uses a small storage device or volume, then tune accordingly.

In this test, the F: drive is an iSCSI RAID protected volume, however you could use other storage interfaces supported by Windows including other block DAS or SAN (e.g. SATA, SAS, USB, iSCSI, FC, FCoE, etc) as well as NAS. Also common to the following commands is using 16 threads and 32 outstanding I/Os to simulate concurrent activity of many users, or application processing threads.

Another common parameter used in the following was -r for random, 7200 seconds (e.g. two hour) test duration time, display latency ( -L ) disable hardware and software cache ( -h), forcing cpu affinity (-a0,1,2,3). Since the test ran on a server with four cores I wanted to see if I could use those for helping to keep the threads and storage busy. What varies in the commands below is the percentage of reads vs. writes, as well as the results output file. Some of the workload below also had the -S option specified to disable OS I/O buffering (to view how buffering helps when enabled or disabled). Depending on the goal, or type of test, validation, or workload being run, I would choose to set some of these parameters differently.

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -w0 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noh_write000.txt

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -w50 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noh_write050.txt

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -w100 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noh_write100.txt

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -S -w0 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noSh_test_write000.txt

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -S -w50 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noSh_write050.txt

diskspd -c45g -b8K -t16 -o32 -r -d7200 -h -S -w100 -L -a0,1,2,3 F:\diskspd.dat >> SIOWS2012R203_Eiscsi_145_noSh_write100.txt

The following is the output from the above workload command.
Microsoft Diskspd sample output

Note that as with any benchmark, workload test or simulation your results will vary. In the above the server, storage and I/O system were not tuned as the focus was on working with the tool, determining its capabilities. Thus do not focus on the performance results per say, rather what you can do with Diskspd as a tool to try different things. Btw, fwiw, in the above example in addition to using an iSCSI target, the Windows 2012 R2 server was a guest on a VMware ESXi 5.5 system.

Where to learn more

The following are related links to read more about server (cloud, virtual and physical) storage I/O benchmarking tools, technologies and techniques.

Drew Robb’s benchmarking quick reference guide
Server storage I/O benchmarking tools, technologies and techniques resource page
Server and Storage I/O Benchmarking 101 for Smarties.
Microsoft Diskspd download and Microsoft Diskspd overview (via Technet)
I/O, I/O how well do you know about good or bad server and storage I/Os?
Server and Storage I/O Benchmark Tools: Microsoft Diskspd (Part I and Part II)

Comments and wrap-up

What I like about Diskspd (Pros)

Reporting including CPU usage (you can’t do server and storage I/O without CPU) along with IOP’s (activity), bandwidth (throughout or amount of data being moved), per thread and total results along with optional reporting. While a GUI would be nice particular for beginners, I’m used to setting up scripts for different workloads so having an extensive options for setting up different workloads is welcome. Being associated with a specific OS (e.g. Windows) the CPU affinity and buffer management controls will be handy for some projects.

Diskspd has the flexibility to use different storage interfaces and types of storage including files or partitions should be taken for granted, however with some tools don’t take things for granted. I like the flexibility to easily specify various IO sizes including large 1MByte, 10MByte, 20MByte, 100MByte and 500MByte to simulate application workloads that do large sequential (or random) activity. I tried some IO sizes (e.g. specified by -b parameter larger than 500MB however, I received various errors including "Could not allocate a buffer bytes for target" which means that Diskspd can do IO sizes smaller than that. While not able to do IO sizes larger than 500MB, this is actually impressive. Several other tools I have used or with have IO size limits down around 10MByte which makes it difficult for creating workloads that do large IOP’s (note this is the IOP size, not the number of IOP’s).

Oh, something else that should be obvious however will state it, Diskspd is free unlike some industry de-facto standard tools or workload generators that need a fee to get and use.

Where Diskspd could be improved (Cons)

For some users a GUI or configuration wizard would make the tool easier to get started with, on the other hand (oth), I tend to use the command capabilities of tools. Would also be nice to specify ranges as part of a single command such as stepping through an IO size range (e.g. 4K, 8K, 16K, 1MB, 10MB) as well as read write percentages along with varying random sequential mixes. Granted this can easily be done by having a series of commands, however I have become spoiled by using other tools such as vdbench.

Summary

Overall I like Diskspd and have added it to my Server Storage I/O workload and benchmark tool-box

Keep in mind that the best benchmark or workload generation technology tool will be your own application(s) configured to run as close as possible to production activity levels.

However when that is not possible, the an alternative is to use tools that have the flexibility to be configured as close as possible to your application(s) workload characteristics. This means that the focus should not be as much on the tool, as opposed to how flexible is a tool to work for you, granted the tool needs to be robust.

Having said that, Microsoft Diskspd is a good and extensible tool for benchmarking, simulation, validation and comparisons, however it will only be as good as the parameters and configuration you set it up to use.

Check out Microsoft Diskspd and add it to your benchmark and server storage I/O tool-box like I have done.

Ok, nuff said (for now)

Cheers gs

Greg Schulz – Author Cloud and Virtual Data Storage Networking (CRC Press), The Green and Virtual Data Center (CRC Press) and Resilient Storage Networks (Elsevier)
twitter @storageio