On 09/21/2017 10:19 AM, Maged Mokhtar wrote: > On 2017-09-21 10:01, Dietmar Rieder wrote: > >> Hi, >> >> I'm in the same situation (NVMEs, SSDs, SAS HDDs). I asked the same >> questions to myself. >> For now I decided to use the NVMEs as wal and db devices for the SAS >> HDDs and on the SSDs I colocate wal and db. >> >> However, I'm still wonderin how (to what size) and if I should change >> the default sizes of wal and db. >> >> Dietmar >> >> On 09/21/2017 01:18 AM, Alejandro Comisario wrote: >>> But for example, on the same server i have 3 disks technologies to >>> deploy pools, SSD, SAS and SATA. >>> The NVME were bought just thinking on the journal for SATA and SAS, >>> since journals for SSD were colocated. >>> >>> But now, exactly the same scenario, should i trust the NVME for the SSD >>> pool ? are there that much of a gain ? against colocating block.* on >>> the same SSD? >>> >>> best. >>> >>> On Wed, Sep 20, 2017 at 6:36 PM, Nigel Williams >>> <nigel.williams@xxxxxxxxxxx <mailto:nigel.williams@xxxxxxxxxxx> >>> <mailto:nigel.williams@xxxxxxxxxxx >>> <mailto:nigel.williams@xxxxxxxxxxx>>> wrote: >>> >>> On 21 September 2017 at 04:53, Maximiliano Venesio >>> <massimo@xxxxxxxxxxx <mailto:massimo@xxxxxxxxxxx> >>> <mailto:massimo@xxxxxxxxxxx <mailto:massimo@xxxxxxxxxxx>>> wrote: >>> >>> Hi guys i'm reading different documents about bluestore, and it >>> never recommends to use NVRAM to store the bluefs db, >>> nevertheless the official documentation says that, is better to >>> use the faster device to put the block.db in. >>> >>> >>> Likely not mentioned since no one yet has had the opportunity to >>> test it. >>> >>> So how do i have to deploy using bluestore, regarding where i >>> should put block.wal and block.db ? >>> >>> >>> block.* would be best on your NVRAM device, like this: >>> >>> ceph-deploy osd create --bluestore c0osd-136:/dev/sda --block-wal >>> /dev/nvme0n1 --block-db /dev/nvme0n1 >>> >>> >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> >>> <mailto:ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx>> >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> <http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com> >>> >>> >>> >>> >>> -- >>> *Alejandro Comisario* >>> *CTO | NUBELIU* >>> E-mail: alejandro@xxxxxxxxxxx <mailto:alejandro@xxxxxxxxxxx> >>> <mailto:alejandro@xxxxxxxxxxx <mailto:alejandro@xxxxxxxxxxx>>Cell: +54 9 >>> 11 3770 1857 >>> _ >>> www.nubeliu.com <http://www.nubeliu.com> <http://www.nubeliu.com/> >>> >>> >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > > My guess is for wal: you are dealing with a 2 step io operation so in > case it is collocated on your SSDs your iops for small writes will be > halfed. The decision is if you add a small NVMEs as wal for 4 or 5 > (large) SSDs, you will double their iops for small io sized. This is not > the case for db. > > For wal size: 512 MB is recommended ( ceph-disk default ) > > For db size: a "few" GB..probably 10GB is a good number. I guess we will > hear more in the future. > Hi, you are right, putting the wal.db for the SSDs (we don't have many, 2/node) on the NVMEs as well might be good. Dietmar -- _________________________________________ D i e t m a r R i e d e r, Mag.Dr. Innsbruck Medical University Biocenter - Division for Bioinformatics Innrain 80, 6020 Innsbruck
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