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CEPH would be one of those, which is more like a database using raw devices, and no linux filesystem (nor VFS calls) in between. It used to run on top of xfs, b
by IcePic 3y ago
CEPH would be one of those, which is more like a database using raw devices, and no linux filesystem (nor VFS calls) in between. It used to run on top of xfs, but now storage nodes (OSDs) talks directly to a raw device (or an lvm on top of it).
But you can most certainly not run "ls" on such a host and get a listing of what some user wrote over S3 into it.
- jonhohle 3y agoAre there any benchmarks that justify bypassing VFS? My Google-fu is failing and the one page I found comparing file systems in the CEPH docs doesn’t talk about raw access, all images are broken (stored on CEPH raw storage?), and the text doesn’t seem to include throughout numbers.
- tryauuum 3y agohttps://www.pdl.cmu.edu/PDL-FTP/Storage/ceph-exp-sosp19.pdf https://www.pdl.cmu.edu/PDL-FTP/Storage/ceph-exp-sosp19.pdf my google-fu found this it's hard to read and summarize. It seems that the main point is that filesystems don't expose many tools ceph needs
- IcePic 3y agoIf you store stuff on xfs or ext4, it will cause more writes due to the journal, and since ceph is a DB in some sense, it also keeps a journal/WAL so doubling that is a waste.