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 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 > >
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