[ceph-users] Sizing for bluestore db and wal

Felix Stolte f.stolte at fz-juelich.de
Mon Nov 26 01:09:55 PST 2018

Hi folks,

i upgraded our ceph cluster from jewel to luminous and want to migrate 
from filestore to bluestore. Currently we use one SSD as journal for 
thre 8TB Sata Drives with a journal partition size of 40GB. If my 
understanding of the bluestore documentation is correct, i can use a wal 
partition for the writeahead log (to decrease write latency, similar to 
filestore) and a db partition for metadata (decreasing write AND read 
latency/throughput). Now I have two questions:

a) Do I really need an WAL partition if both wal and db are on the same SSD?

b) If so, what would the ratio look like? 99% db, 1% wal?

Best regards, Felix

Forschungszentrum Jülich GmbH
52425 Jülich
Sitz der Gesellschaft: Jülich
Eingetragen im Handelsregister des Amtsgerichts Düren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir. Dr. Karl Eugen Huthmacher
Geschäftsführung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender),
Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt,
Prof. Dr. Sebastian M. Schmidt

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