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SATA & SSD Pool Setup


trexman
60 Posts
November 21, 2018, 3:56 pm

Hello,

I don't fully understand the setup of two pools (SATA and SSD). After the setup of a new PetaSAN cluster I did the following steps

  1. Added all ODSs SATA and SSD to the cluster (SSD without journal)
  2. Deleted the default pool
  3. Created two crush rules with the by-host-hdd and by-host-ssd template
  4. Created two pools with each of that crush rules

Now I have to say THANK YOU for that easy setup!

After this setup i looked at the OSD tree:

ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF
-1 15.01657 root default
-5 5.48087 host HBPS01
10 hdd 0.45499 osd.10 up 1.00000 1.00000
11 hdd 0.45499 osd.11 up 1.00000 1.00000
12 hdd 0.45499 osd.12 up 1.00000 1.00000
13 hdd 0.45499 osd.13 up 1.00000 1.00000
14 hdd 0.45499 osd.14 up 1.00000 1.00000
15 hdd 0.45499 osd.15 up 1.00000 1.00000
16 hdd 0.45499 osd.16 up 1.00000 1.00000
17 hdd 0.45499 osd.17 up 1.00000 1.00000
18 hdd 0.45499 osd.18 up 1.00000 1.00000
19 hdd 0.45499 osd.19 up 1.00000 1.00000
30 ssd 0.93100 osd.30 up 1.00000 1.00000
-7 4.76785 host HBPS02
20 hdd 0.45499 osd.20 up 1.00000 1.00000
21 hdd 0.45499 osd.21 up 1.00000 1.00000
22 hdd 0.45499 osd.22 up 1.00000 1.00000
23 hdd 0.45499 osd.23 up 1.00000 1.00000
24 hdd 0.45499 osd.24 up 1.00000 1.00000
25 hdd 0.45499 osd.25 up 1.00000 1.00000
26 hdd 0.45499 osd.26 up 1.00000 1.00000
27 hdd 0.45499 osd.27 up 1.00000 1.00000
28 hdd 0.45499 osd.28 up 1.00000 1.00000
29 hdd 0.45499 osd.29 up 1.00000 1.00000
31 ssd 0.21799 osd.31 up 1.00000 1.00000
-3 4.76785 host HBPS03
0 hdd 0.45499 osd.0 up 1.00000 1.00000
1 hdd 0.45499 osd.1 up 1.00000 1.00000
2 hdd 0.45499 osd.2 up 1.00000 1.00000
3 hdd 0.45499 osd.3 up 1.00000 1.00000
4 hdd 0.45499 osd.4 up 1.00000 1.00000
5 hdd 0.45499 osd.5 up 1.00000 1.00000
6 hdd 0.45499 osd.6 up 1.00000 1.00000
7 hdd 0.45499 osd.7 up 1.00000 1.00000
8 hdd 0.45499 osd.8 up 1.00000 1.00000
9 hdd 0.45499 osd.9 up 1.00000 1.00000
32 ssd 0.21799 osd.32 up 1.00000 1.00000

Now the part what i don't understand. In my head i was expecting an OSD tree like that:

ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF
-0 15.01657 root sata 
-5 5.48087 host HBPS01-sata
10 hdd 0.45499 osd.10 up 1.00000 1.00000
11 hdd 0.45499 osd.11 up 1.00000 1.00000
12 hdd 0.45499 osd.12 up 1.00000 1.00000
13 hdd 0.45499 osd.13 up 1.00000 1.00000
14 hdd 0.45499 osd.14 up 1.00000 1.00000
15 hdd 0.45499 osd.15 up 1.00000 1.00000
16 hdd 0.45499 osd.16 up 1.00000 1.00000
17 hdd 0.45499 osd.17 up 1.00000 1.00000
18 hdd 0.45499 osd.18 up 1.00000 1.00000
19 hdd 0.45499 osd.19 up 1.00000 1.00000
-0 15.01657 root ssd 
-5 5.48087 host HBPS01-ssd
30 ssd 0.93100 osd.30 up 1.00000 1.00000

...
This is not a real output. I made this up.

So i tried to get this with the OSD Bucket Tree but i guess that is something different.

Source of my confusion is the Blog of Sébastien Han: https://www.sebastien-han.fr/blog/2014/08/25/ceph-mix-sata-and-ssd-within-the-same-box/

It this separation of HDD and SSD class drives in PetaSAN not needed?

Thanks.

#1

admin
2,930 Posts
November 21, 2018, 6:06 pm

Not needed,  it is feature in Ceph added in Luminous. the blog entry is the older way to do this.

#2