Monitoring Splunk
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How many IOPS can I expect from a disk?

Splunk Employee
Splunk Employee

For a 10K or 15K disk, roughly how many IOPS would I expect to be available?

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Re: How many IOPS can I expect from a disk?

Splunk Employee
Splunk Employee

For a 10K disk, the expected aproximate range would be 166.67 to 90.9 IOPS
For a 15K disk, aproximately 210 IOPS

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Re: How many IOPS can I expect from a disk?

Splunk Employee
Splunk Employee

Here are some average ballpark numbers by drive type. Your mileage may vary, and raid configuration will heavily influence aggregate drive numbers.

Device      Type  IOPS             Interface
=========== ===== ================ ===========
7,200 rpm   SATA  ~75-100 IOPS[2]  SATA 3 Gb/s
10,000 rpm  SATA  ~125-150 IOPS[2] SATA 3 Gb/s
10,000 rpm  SAS   ~140 IOPS[2]     SAS
15,000 rpm  SAS   ~175-210 IOPS[2] SAS

I think the general message here is, stay away from SATA for Splunk installations. The only place SATA has in a Splunk install, is as possibly cold storage, or archive storage. Search performance will suffer whenever SATA is called upon.

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Re: How many IOPS can I expect from a disk?

Path Finder

If you want the detailed explanation: http://en.wikipedia.org/wiki/IOPS

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Re: How many IOPS can I expect from a disk?

Explorer

Here are some measured results of how many IOPs can be done across various HDDs, SSDs, SSHD/HHDDs with varying workload (IO Size, reads, writes, random, sequential) along with associated bandwidth as well as latency. Of course your millage will vary...
http://storageioblog.com/part-ii-iops-hdd-hhdd-ssd/

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Re: How many IOPS can I expect from a disk?

Explorer

Keep in mind that the IOPs will vary depending on if they are random or sequential, read or write. Also if the IOs are small or large (larger IO size will result in lower IOPs however higher bandwidth and vise versa). For example, the 1TB 7.2K 6Gb SATA WD drives performance varies under different workloads, including some "high IOPs" due to sequential read bufferings.
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Sequential read IOPs should be higher due to buffering at the server, adapter, raid card or controller as well as drive. Most drives today have some amount of read cache even some of the lower cost SATA drives. Likewise some of the higher-end SATA drives will have larger read caches not to be confused with the hybrid/HHDD/SSHD devices which do even more caching of reads and with some, also cached writes. Something else that will impact the IOPs are how much concurrency or activity being sent to the drive, granted the drive has to be able to support the activity. Otoh, a drive that can support more IOPs may not be being pushed due to how much concurrent work being done. Other factors and considerations include the OS, queue depths, driver config, interface (e.g. 3Gb, 6Gb, 12Gb SAS or SATA), RAID among other things.

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