charm-specs/specs/newton/approved/ceph-autotune.rst

Ceph Autotune

Ceph isn't as fast as it could be out of the box.

Problem Description

Currently we don’t do any tuning of Ceph after installing it. There’s many little things that have to be tweaked to get ceph to be performant. There are many mailing list messages of users becoming frustrated with the slow performance of Ceph. The goal of this epic is to capture the low hanging fruit so everyone can have a better experience with Ceph.

Proposed Change

I'm proposing several areas where easy improvements can be made. There's several areas that can be improved such as HDD read ahead and max hardware sector settings. We can also tune the sysctl network settings on 10 and 40Gb networks. Finally I've noticed that IRQ alignment on multisocket motherboard isn't ideal. We can use numactl to pin the IRQs for all the components in the IO path from network to osd to disk. Of all the changes probably the IRQ pinning will be the most difficult.

Alternatives

None

Implementation

Assignee(s)

Primary assignee:

cholcombe973

Gerrit Topic

git-review -t performance-optimizations

Work Items

1. HDD Read ahead settings

• Often times the read ahead settings for hdd’s are too small for storage servers.

2. 10/40Gb sysctl settings

• 10Gb and 40Gb networks need special sysctl settings to improve their performance.

3. HDD max hardware sectors

• Making the max hardware sectors as large as possible allows bigger sequential writes and therefore better performance.

4. IRQ alignment for multisocket motherboards

• It has been shown on multi socket motherboards that Linux does a bad job of lining up IRQ’s and results in lots of swapping of cache memory between CPU’s. This significantly degrades Ceph’s performance.

Repositories

https://github.com/openstack/charm-ceph-osd/

Documentation

Updates to the README's in the impacted charms will be made as part of this change.

Security

No additional security concerns.

Testing

Code changes will be covered by unit tests; functional testing will be done using a Mojo specification.

Dependencies

• charm-layering