Filestore, pre-ceph-volume may have been entirely different. IIRC LVM is used these days to exploit persistent metadata tags.
> On Apr 11, 2025, at 4:03 PM, Tim Holloway <t...@mousetech.com> wrote: > > I just checked an OSD and the "block" entry is indeed linked to storage using > a /dev/mapper uuid LV, not a /dev/device. When ceph builds an LV-based OSD, > it creates a VG whose name is "ceph-uuuuu", where "uuuu" is a UUID, and an LV > named "osd-block-vvvv", where "vvvv" is also a uuid. So although you'd map > the osd to something like /dev/vdb in a VM, the actual name ceph uses is > uuid-based (and lvm-based) and thus not subject to change with alterations in > the hardware as the uuids are part of the metadata in VGs and LVs created by > ceph. > > Since I got that from a VM, I can't vouch for all cases, but I thought it > especially interesting that a ceph was creating LVM counterparts even for > devices that were not themselves LVM-based. > > And yeah, I understand that it's the amount of OSD replicate data that counts > more than the number of hosts, but when an entire host goes down and there > are few hosts, that can take a large bite out of the replicas. > > Tim > > On 4/11/25 10:36, Anthony D'Atri wrote: >> I thought those links were to the by-uuid paths for that reason? >> >>> On Apr 11, 2025, at 6:39 AM, Janne Johansson <icepic...@gmail.com> wrote: >>> >>> Den fre 11 apr. 2025 kl 09:59 skrev Anthony D'Atri >>> <anthony.da...@gmail.com>: >>>> Filestore IIRC used partitions, with cute hex GPT types for various states >>>> and roles. Udev activation was sometimes problematic, and LVM tags are >>>> more flexible and reliable than the prior approach. There no doubt is >>>> more to it but that’s what I recall. >>> Filestore used to have softlinks towards the journal device (if used) >>> which pointed to sdX where that X of course would jump around if you >>> changed the number of drives on the box, or the kernel disk detection >>> order changed, breaking the OSD. >>> >>> -- >>> May the most significant bit of your life be positive. >>> _______________________________________________ >>> ceph-users mailing list -- ceph-users@ceph.io >>> To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
