Hi, If you don't specifiy WAL it will be located on the same drive as the rocksdb. You need to specify wal if you have faster disk the your rocksdb, like DATA on HDD, Rocksdb on SSD, wal on nvme/optane. In the past they suggested like this: 300GB data 30GB rocksdb, 3GB wal. Not sure is this still true. Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com --------------------------------------------------- -----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:27 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Bluestore OSD Layout - WAL, DB, Journal Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________ Hello, I'm in the process of doubling the number of OSD nodes in my Nautilus cluster - from 3 to 6. Based on answers receive from earlier posts to this list, the new nodes have more NVMe that the old nodes. More to the point, on the original nodes the amount of NVMe allocated to each OSD was about 120GB, so the RocksDB was limited to 30GB. However, for my workload 300GB is probably recommended. As I prepare to lay out the NVMe on these new nodes, I'm still trying to understand how to size the DB and WAL for my OSDs and whether Journal is even needed. According to https://docs.ceph.com/en/nautilus/ceph-volume/lvm/prepare/ <https://docs.ceph.com/en/nautilus/ceph-volume/lvm/prepare/>
Bluestore supports the following configurations:
* A block device, a block.wal, and a block.db device * A block device and a block.wal device * A block device and a block.db device * A single block device
First question: On my first nodes I managed to get a DB, but no WAL. My current perception is that WAL and DB occupy separate physical/logical partitions. By specifying a WAL size and a DB size, ceph-volume will create the corresponding logical volumes on the NVMe. Is this correct? It is also possible to lay these out as basic logical partitions? Second question: How do I decide whether I need WAL, DB, or both? Third question: Once I answer the above WAL/DB question, what are the guidelines for sizing them? Thanks. -Dave -- Dave Hall Binghamton University _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io ________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.