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I have many CentOS systems, some of them have traditional hard disks, some SSD, and some mix of them. I would like to change scheduler for SSD to deadline.

So at runtime I can simply scan check devices and for ones that have /sys/block/sd?/queue/rotational as 0. I could enable deadline by doing echo 'deadline' > /sys/block/sda/queue/scheduler

But what about permanent changes? Some tuned profiles enable deadline scheduler, but if there is mixed (some normal, some SSD), for which disks would this be applied?

For example:

tuned-adm profile latency-performance

From https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Power_Management_Guide/tuned-adm.html

latency-performance A server profile for typical latency performance tuning. This profile disables dynamic tuning mechanisms and transparent hugepages. It uses the performance governer for p-states through cpuspeed, and sets the I/O scheduler to deadline. Additionally, in Red Hat Enterprise Linux 6.5 and later, the profile requests a cpu_dma_latency value of 1. In Red Hat Enterprise Linux 6.4 and earlier, cpu_dma_latency requested a value of 0.

So if I have several disks, for which deadline would be applied?

gilbertasm
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  • Are you using RAID controllers? What types of hardware (makes and models) are involved? – ewwhite Jul 20 '15 at 17:20
  • You can write a custom profile, which takes about a minute, but in my experience deadline works best for most workloads on spinning rust as well, so maybe you don't need to bother changing. – Michael Hampton Jul 20 '15 at 17:27
  • The servers are actually client servers, there we install our product. But mostly for SSD disks, there are two disk software (mdam) RAID1 systems – gilbertasm Jul 20 '15 at 17:28

1 Answers1

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While you could write a customer profile or modify one of the existing, I'd recommend tuned-adm profile enterprise-storage based on your hardware information.

If you need more changes beyond that, just use "enterprise-storage" as a baseline.

ewwhite
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