IOPS

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Input/output performance measurement

title: "IOPS" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["benchmarks-(computing)", "data-transmission", "units-of-frequency"] description: "Input/output performance measurement" topic_path: "technology/computing" source: "https://en.wikipedia.org/wiki/IOPS" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Input/output performance measurement ::

Input/output operations per second (IOPS, pronounced eye-ops) is an input/output performance measurement used to characterize computer storage devices like hard disk drives (HDD), solid state drives (SSD), and storage area networks (SAN). Like benchmarks, IOPS numbers published by storage device manufacturers do not directly relate to real-world application performance.

Background

To meaningfully describe the performance characteristics of any storage device, it is necessary to specify a minimum of three metrics simultaneously: IOPS, response time, and (application) workload. Absent simultaneous specifications of response-time and workload, IOPS are essentially meaningless. In isolation, IOPS can be considered analogous to "revolutions per minute" of an automobile engine i.e. an engine capable of spinning at 10,000 RPMs with its transmission in neutral does not convey anything of value, however an engine capable of developing specified torque and horsepower at a given number of RPMs fully describes the capabilities of the engine.

The specific number of IOPS possible in any system configuration will vary greatly, depending upon the variables the tester enters into the program, including the balance of read and write operations, the mix of sequential and random access patterns, the number of worker threads and queue depth, as well as the data block sizes.

Performance characteristics

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/a7/Random_vs_sequential_access.svg" caption="Random access compared to sequential access"] ::

The most common performance characteristics measured are sequential and random operations. Sequential operations access locations on the storage device in a contiguous manner and are generally associated with large data transfer sizes, e.g. ≥ 128 kB. Random operations access locations on the storage device in a non-contiguous manner and are generally associated with small data transfer sizes, e.g. 4 kB.

The most common performance characteristics are as follows:

::data[format=table]

MeasurementDescriptionTotal IOPSRandom read IOPSRandom write IOPSSequential read IOPSSequential write IOPS
Total number of I/O operations per second
(when performing a mix of read and write tests)
Average number of random read I/O operations per second
Average number of random write I/O operations per second
Average number of sequential read I/O operations per second
Average number of sequential write I/O operations per second
::

For HDDs and similar electromechanical storage devices, the random IOPS numbers are primarily dependent upon the storage device's random seek time, whereas, for SSDs and similar solid state storage devices, the random IOPS numbers are primarily dependent upon the storage device's internal controller and memory interface speeds. On both types of storage devices, the sequential IOPS numbers (especially when using a large block size) typically indicate the maximum sustained bandwidth that the storage device can handle. Often sequential IOPS are reported as a simple Megabytes per second number as follows:

: (Then converted to MB/s.)

Some HDDs/SSDs will improve in performance as the number of outstanding IOs (i.e. queue depth) increases. This is usually the result of more advanced controller logic on the drive performing command queuing and reordering commonly called either Tagged Command Queuing (TCQ) or Native Command Queuing (NCQ). Many consumer SATA HDDs either cannot do this, or their implementation is so poor that no performance benefit can be seen. Enterprise class SATA HDDs, such as the Western Digital Raptor and Seagate Barracuda NL will improve by nearly 100% with deep queues.

While traditional HDDs have about the same IOPS for read and write operations, many NAND flash-based SSDs and USB sticks are much slower writing than reading due to the inability to rewrite directly into a previously written location forcing a procedure called garbage collection. This has caused hardware test sites to start to provide independently measured results when testing IOPS performance.

Flash SSDs, such as the Intel X25-E (released 2010), have much higher IOPS than traditional HDD. In a test done by Xssist, using Iometer, 4 KB random transfers, 70/30 read/write ratio, queue depth 4, the IOPS delivered by the Intel X25-E 64 GB G1 started around 10000 IOPs, and dropped sharply after 8 minutes to 4000 IOPS, and continued to decrease gradually for the next 42 minutes. IOPS vary between 3000 and 4000 from approximately 50 minutes and onwards, for the rest of the 8+ hours the test ran. Even with the drop in random IOPS after the 50th minute, the X25-E still has much higher IOPS compared to traditional hard disk drives. Some SSDs, including the OCZ RevoDrive 3 x2 PCIe using the SandForce controller, have shown much higher sustained write performance that more closely matches the read speed. For example, a typical operating system has many small files (such as DLLs ≤ 128 kB), so SSD is more suitable for system drive.

Examples

Mechanical hard drives

Block size used when testing significantly affects the number of IOPS performed by a given drive. See below for some typical performance figures: ::data[format=table] | colspan="2" | align=right}} | Metric → | IOPS | IOPS | MB/s | IOPS | IOPS | MB/s | Drive | align=right}} |Block size → | large | Type | RPM | align=right|clas=table-rh unsortable}} |Access type → | random | random | random | random | random | sequential | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | SAS | | | 188 – 203 | 175 – 192 | 11.2 – 12.3 | 115 – 135 | 58.9 – 68.9 | 91.5 – 126.3 | | | | | | | | | | | | | FC | | | 163 – 178 | 151 – 169 | 9.7 – 10.8 | 97 – 123 | 49.7 – 63.1 | 73.5 – 127.5 | | | | | | | | | | | | | FC | | | 142 – 151 | 130 – 143 | 8.3 – 9.2 | 80 – 104 | 40.9 – 53.1 | 58.1 – 107.2 | | | | | | | | | | | | | SAS | | | 142 – 151 | 130 – 143 | 8.3 – 9.2 | 80 – 104 | 40.9 – 53.1 | 58.1 – 107.2 | | | | | | | | | | | | | SATA | 7200 | | 73 – 79 | 69 – 76 | 4.4 – 4.9 | 47 – 63 | 24.3 – 32.1 | 43.4 – 97.8 | | | | | | | | | | | | | SATA | 5400 | | 57 | 55 | 3.5 | 44 | 22.6 | | HDD | ~290 IOPS | SATA 3 Gb/s | fio -readonly -name iops -rw=randread -bs=512 -runtime=20 -iodepth 24 -filename /dev/sda -ioengine libaio -direct=1 | | | | | | | | ::

Solid-state devices

::data[format=table]

DeviceTypeIOPSInterfaceNotes
Intel X25-M G2 (MLC)SSD~8,600 IOPSSATA 3 Gbit/sIntel's data sheet claims 6,600/8,600 IOPS (80 GB/160 GB version) and 35,000 IOPS for random 4 KB writes and reads, respectively.
Intel X25-E (SLC)SSD~5,000 IOPSSATA 3 Gbit/sIntel's data sheet claims 3,300 IOPS and 35,000 IOPS for writes and reads, respectively. 5,000 IOPS are measured for a mix. Intel X25-E G1 has around 3 times higher IOPS compared to the Intel X25-M G2.
G.Skill Phoenix ProSSDurl=http://www.tweakpc.de/hardware/tests/ssd/gskill_phoenix_pro/s05.phptitle=G.Skill Phoenix Pro 120 GB Test - SandForce SF-1200 SSD mit 50K IOPS - HD Tune Access Time IOPS (Diagramme) (5/12)website=TweakPC.de
Samsung SSD 850 PROSSDUp to 100,000 read IOPS
Up to 90,000 write IOPSSATA 6 Gbit/s4 KB aligned random I/O at QD32
10,000 read IOPS, 36,000 write IOPS at QD1
550 MB/s sequential read, 520 MB/s sequential write on 256 GB and larger models
550 MB/s sequential read, 470 MB/s sequential write on 128 GB model
Virident Systems tachIOnSSDUp to 320,000 sustained READ IOPS using 4 kB blocks, and up to 200,000 sustained WRITE IOPS using 4kB blocksPCIe
OCZ RevoDrive 3 X2SSDUp to 200,000 random write 4k IOPSPCIe
DDRdrive X1SSDUp to 300,000+ (512B random read IOPS) and 200,000+ (512B random write IOPS)PCIe
Samsung SSD 960 EVOSSDUp to 380,000 read IOPS
Up to 360,000 write IOPSNVMe over PCIe 3.0 x4, M.2last1=Ramseyerfirst1=Christitle=Samsung 960 Pro SSD Review
14,000 read IOPS, 50,000 write IOPS at QD1
330,000 read IOPS, 330,000 write IOPS on 500 GB model
300,000 read IOPS, 330,000 write IOPS on 250 GB model
Up to 3.2 GB/s sequential read, 1.9 GB/s sequential write
Samsung SSD 960 PROSSDUp to 440,000 read IOPS
Up to 360,000 write IOPSNVMe over PCIe 3.0 x4, M.2date=January 2024}} 3.5 GB/s sequential read, 2.1 GB/s sequential write
Kaminario K2SSDUp to 2,000,000 IOPS.
1,200,000 IOPS in SPC-1 benchmark simulating business applicationsFCMLC Flash
NetApp FAS6240 clusterFlash/Disk1,261,145 SPECsfs2008 nfsv3 IOPs using 1,440 15k disks, across 60 shelves, with virtual storage tiering.NFS, SMB, FC, FCoE, iSCSISPECsfs2008 is the latest version of the Standard Performance Evaluation Corporation benchmark suite measuring file server throughput and response time, providing a standardized method for comparing performance across different vendor platforms.
EMC DSSD D5FlashUp to 10 million IOPSPCIe Out of Box, up to 48 clients with high availability.PCIe Rack Scale Flash Appliance. Product discontinued.
::

References

References

  1. Lowe, Scott. (2010-02-12). "Calculate IOPS in a storage array".
  2. (2012-08-03). "Getting The Hang Of IOPS v1.3".
  3. Smith, Kent. (2009-08-11). "Benchmarking SSDs: The Devil is in the Preconditioning Details".
  4. (2006-07-13). "SATA in the Enterprise - A 500 GB Drive Roundup {{pipe}} StorageReview.com - Storage Reviews".
  5. (2009-05-04). "Write Amplification Analysis in Flash-Based Solid State Drives". [[IBM]].
  6. "SSDs - Write Amplification, TRIM and GC". OCZ Technology.
  7. "Intel Solid State Drives". Intel.
  8. (2010-03-27). "Intel X25-E 64GB G1, 4KB Random IOPS, iometer benchmark".
  9. (2011-06-28). "OCZ RevoDrive 3 x2 PCIe SSD Review – 1.5GB Read/1.25GB Write/200,000 IOPS As Little As $699".
  10. "SSD vs. HDD: Which Do You Need?".
  11. "RAID Performance Calculator - WintelGuy.com".
  12. (2008-09-08). "Intel's X25-M Solid State Drive Reviewed".
  13. (January 2010). "Intel X18-M/X25-M SATA Solid State Drive — 34 nm Product Line". Intel.
  14. (27 February 2009). "Intel's X25-E SSD Walks All Over The Competition: They Did It Again: X25-E For Servers Takes Off".
  15. (January 2009). "Intel X25-E SATA Solid State Drive: Product Manual". Intel.
  16. (May 2010). "Intel X25-E G1 vs Intel X25-M G2 Random 4 KB IOPS, iometer".
  17. "G.Skill Phoenix Pro 120 GB Test - SandForce SF-1200 SSD mit 50K IOPS - HD Tune Access Time IOPS (Diagramme) (5/12)".
  18. "Samsung SSD 850 PRO Specifications". [[Samsung Electronics]].
  19. "Virident's tachIOn SSD flashes by". theregister.co.uk.
  20. (2011-06-28). "OCZ RevoDrive 3 X2 480GB Review {{pipe}} StorageReview.com - Storage Reviews".
  21. "Introducing the DDRdrive X1: Redefining Solid-State Storage".
  22. "DDRDrive - The drive for speed".
  23. "DDRDrive - The drive for speed".
  24. Allyn Malventano. (2009-05-04). "DDRdrive hits the ground running - PCI-E RAM-based SSD {{pipe}} PC Perspective".
  25. "NVMe SSD 960 PRO/EVO".
  26. (18 October 2016). "Samsung 960 Pro SSD Review".
  27. Lyle Smith. "Kaminario Boasts Over 2 Million IOPS and 20 GB/s Throughput on a Single All-Flash K2 Storage System".
  28. Mellor, Chris. (2012-07-30). "Chris Mellor, The Register, July 30, 2012: "Million-plus IOPS: Kaminario smashes IBM in DRAM decimation"".
  29. "Storage Performance Council: Active SPC-1 Results". Storage Performance Council.
  30. "SpecSFS2008".
  31. "Rack-Scale Flash Appliance - DSSD D5 EMC". EMC.
  32. "Dell kills off standalone DSSD D5, scatters remains into other gear".

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benchmarks-(computing)data-transmissionunits-of-frequency