[PVE-User] Ceph cache tiering

[Alexandre DERUMIER]

A lot of users on ceph mailing have reported problem with samsung evo drives,

mainly because they are pretty slow for O_DSYNC writes

See this for benching them.

http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/


----- Mail original -----
De: "Fabrizio Cuseo" <f.cuseo at panservice.it>
À: "proxmoxve" <pve-user at pve.proxmox.com>
Envoyé: Samedi 16 Mai 2015 10:40:13
Objet: [PVE-User] Ceph cache tiering

Hallo there. 
I am testing the ceph performances with a SSD cache journal. 

My setup is: 

- 3 hosts, 2 x quad opteron, 64 Gbyte, 1 x giga ethernet (for proxmox), 1 infiniband 20Gbit (for ceph), 1 x Perc6I with 7 x WD 1Tbyte 128Mb cache (enterprise edition), 1 for proxmox, 6 for ceph OSD, and 1 x Samsung SSD EVO 850 (240Gbyte); they are configured as 8 different Virtual Disk on the raid controller. 

I tested the first setup; ceph OSD each with the journal on the single SSD. 

My first performances test (with only 1 VM) are about 150Mbyte/sec write. 


Now, I would like to test a different ceph setup: 

6 x OSD (with 1Tbyte sata disk) and Journal on the same disk 

1 x SSD (one for each node), configured as OSD of a different crush map, using the cache tiering configuration. 

My two questions are: 
- have someone tested this setup ? Performs better than the first ? 
- will be planned in proxmox gui some option to create OSD in a different pool, or the only options (in future too) is to manually modify the crush map and manually create the SSD OSDs ? It will be fine to have all managed by proxmox gui, both to create and monitor. 

Regards, Fabrizio 


-- 
--- 
Fabrizio Cuseo - mailto:f.cuseo at panservice.it 
Direzione Generale - Panservice InterNetWorking 
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