Setting up a new Ceph cache pool for better performance

This video discusses how to set up a Ceph cache pool and tier your cache to improve reads and writes. While we could cover many cache settings, I will focus on the most important values you can set on a pool to cache your data effectively.

Write up:

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Outro music: Sanaas Scylla

#ceph #cache #pool

[heiseheise]

I really wish that ceph developers didn't seem hell-bent on removing/deprecating/telling everyone NOT to use this feature. After using several enterprise commercial SANs in my career that use both spinning rust and SSDs - because we're not billionaires and no, we can't afford all-flash, Pure! Stop sending me marketing crap for all-flash SANs! - anyway, it just seems crazy to me that ceph doesn't want to put more development hours into making cache tiering BETTER rather than warning everyone away from it. Why wouldn't I want a pool of SSDs capturing incoming writes at high speed, then demoting it down to the HDDs in the background? This functionality is built into every single SAN of the past 15 years that has multiple speeds of drive in them. Ceph is so good and so functional, and they have a tiering feature... yet they want people to stop using it, rather than improving it? I just don't get it.

[Exalted]

I think can separately test the HDD and SSD cache tiering + HDD

[cmarotta]

A Red Hat certified Enterprise course didn't even cover this, even when directly asked. Excellent video.

[andbuitra]

It was a nice video but it'd have been nice to see statistics about the change in performance

[galle]

Nice video Daniel! Is caching preferred over journal disks or am I mixing apples and oranges?

[deba]

Will Ceph automatically use ssd drives/osds for the hot_storage pool you have created or we have to associate SSDs with that particular pool?

[ap]

Thank you for the guide. I am a ceph beginner.

At 3:48 how does ceph know to put the hot_storage pool in the ssd osd (instead of in the hdd osd). Is this automatic? I already have 2 ssd and 2 hdd setup as osd in the host.

[CJ-vgtg]

Hi again. Do you know what the default time is for the cache_min_flush_age if you don't mually set it? You set it to 10 mins. How can I reset it to the default or none? Thanks

[cmarotta]

What do you think would happen in a Read-Intensive pool if the criteria you set for Data to become promoted to Cache in local RAM far exceeds the amount of local RAM? Do these caching settings care if the Pools are Replicated or Erasure Coded ?

[abonu]

hi Daniel, in writeback mode, do you directly write data to the cachepool or write to the basepool first and then promote_object() to promote the object to the cachepool?

[piotrgocza]

Is it possible to use ONE cache pool for multiple pools with data?

[studentofmgy]

Hi! Can you tell me, please, if the storage pool contains rbd images, all the data inside rbd will be moved to the cache tier? Thanks

[CJ-vgtg]

Hiya. Thanks for the great videos. I do have a doubt about cache tiers. If I have 3 hdd and 3 ssd disks, would it be best to use 1 ssd for the cache tier pool and 3hdd+2ssd for the data pool(set as cold hdd storage)? Thanks

[damiendye]

how do you force hot_storage to only use the NVME disks ?

[ap]

In proxmox, with your guide I have created SSD caching for my HDD pool.

Which pool do I add as the storage pool for vms, the HDD pool?

[mazter]

Hi, can u help me to fix some problems with ceph on proxmox? How can I contact you?