13 Jun
2021
13 Jun
'21
7:29 a.m.
On 6/12/21 4:39 PM, Nathan Fish wrote:
I doubt it. The problem is that the CephFS MDS must
perform
distributed metadata transactions with ordering and locking.
Whereas a filesystem on rbd runs locally and doesn't have to worry
about other computers writing to the same block device.
Our bottleneck in production is usually the MDS CPU load.
Perhaps if an 'exclusive write mount' option existed, the mds could
delegate most of what it does to the client.
Moving 4K-at-least blocks around a network, even with 'jumbo frames' on
local segments, has got to take more processing and network bandwidth
than the 'known interesting only' parts of files.
On Fri, Jun 11, 2021 at 12:31 PM Harry G. Coin <hgcoin(a)gmail.com> wrote:
On any given a properly sized ceph setup, for
other than database end
use) theoretically shouldn't a ceph-fs root out-perform any fs atop a
rados block device root?
Seems to me like it ought to: moving only the 'interesting' bits of
files over the so-called 'public' network should take fewer, smaller
packets than the overhead associated with whole blocks that hold some
fraction of the 'interesting' bits?
Does it work that way in practice?
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