Hi Caspar, Thanx. I don't see any mention that it's a bad idea to have the WAL and DB on the same SSD, but I guess it could improve performance?
I do understand that if I loose the the WAL drive, I loose the OSD's as well. >From what I gather, I can't move the WAL or DB devices and would have to completely rebuild the OSD storage. So, unless there's a compelling reason not to have those two on the same drive On Thu, Nov 23, 2017 at 11:53 AM, Caspar Smit <[email protected]> wrote: > Rudi, > > First off all do not deploy an OSD specifying the same seperate device for > DB and WAL: > > Please read the following why: > > http://docs.ceph.com/docs/master/rados/configuration/bluestore-config-ref/ > > > That said you have a fairly large amount of SSD size available so i > recommend using it as block.db: > > You can specify a fixed size block.db size in ceph.conf using: > > [global] > bluestore_block_db_size = 16106127360 > > The above is a 15GB block.db size > > Now when you deploy an OSD with a seperate block.db device the partition > will be 15GB. > > The default size is a percentage of the device i believe and not always a > usable amount. > > Caspar > > Met vriendelijke groet, > > Caspar Smit > Systemengineer > SuperNAS > Dorsvlegelstraat 13 > 1445 PA Purmerend > > t: (+31) 299 410 414 <+31%20299%20410%20414> > e: [email protected] > w: www.supernas.eu > > 2017-11-23 10:27 GMT+01:00 Rudi Ahlers <[email protected]>: > >> Hi, >> >> Can someone please explain this to me in layman's terms. How big a WAL >> drive do I really need? >> >> I have a 2x 400GB SSD drives used as WAL / DB drive and 4x 8TB HDD's used >> as OSD's. When I look at the drive partitions the DB / WAL partitions are >> only 576Mb & 1GB respectively. This feels a bit small. >> >> >> root@virt1:~# lsblk >> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT >> sda 8:0 0 7.3T 0 disk >> ├─sda1 8:1 0 100M 0 part /var/lib/ceph/osd/ceph-0 >> └─sda2 8:2 0 7.3T 0 part >> sdb 8:16 0 7.3T 0 disk >> ├─sdb1 8:17 0 100M 0 part /var/lib/ceph/osd/ceph-1 >> └─sdb2 8:18 0 7.3T 0 part >> sdc 8:32 0 7.3T 0 disk >> ├─sdc1 8:33 0 100M 0 part /var/lib/ceph/osd/ceph-2 >> └─sdc2 8:34 0 7.3T 0 part >> sdd 8:48 0 7.3T 0 disk >> ├─sdd1 8:49 0 100M 0 part /var/lib/ceph/osd/ceph-3 >> └─sdd2 8:50 0 7.3T 0 part >> sde 8:64 0 372.6G 0 disk >> ├─sde1 8:65 0 1G 0 part >> ├─sde2 8:66 0 576M 0 part >> ├─sde3 8:67 0 1G 0 part >> └─sde4 8:68 0 576M 0 part >> sdf 8:80 0 372.6G 0 disk >> ├─sdf1 8:81 0 1G 0 part >> ├─sdf2 8:82 0 576M 0 part >> ├─sdf3 8:83 0 1G 0 part >> └─sdf4 8:84 0 576M 0 part >> sdg 8:96 0 118G 0 disk >> ├─sdg1 8:97 0 1M 0 part >> ├─sdg2 8:98 0 256M 0 part /boot/efi >> └─sdg3 8:99 0 117.8G 0 part >> ├─pve-swap 253:0 0 8G 0 lvm [SWAP] >> ├─pve-root 253:1 0 29.3G 0 lvm / >> ├─pve-data_tmeta 253:2 0 68M 0 lvm >> │ └─pve-data 253:4 0 65.9G 0 lvm >> └─pve-data_tdata 253:3 0 65.9G 0 lvm >> └─pve-data 253:4 0 65.9G 0 lvm >> >> >> >> >> -- >> Kind Regards >> Rudi Ahlers >> Website: http://www.rudiahlers.co.za >> >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > -- Kind Regards Rudi Ahlers Website: http://www.rudiahlers.co.za
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