Hi,
While looking at something else in the documentation, I came across
this:
https://docs.ceph.com/en/latest/cephfs/administration/#maximum-file-sizes-and-performance
"CephFS enforces the maximum file size limit at the point of appending
to files or setting their size. It does not affect how anything is
stored. When users create a file of an enormous size (without
necessarily writing any data to it), some operations (such as deletes)
cause the MDS to have to do a large number of operations to check if any
of the RADOS objects within the range that could exist (according to the
file size) really existed. The max_file_size setting prevents users from
creating files that appear to be eg. exabytes in size, causing load on
the MDS as it tries to enumerate the objects during operations like
stats or deletes."
Thought it might help.
--
Cordialement,
Frédéric Nass
Direction du Numérique
Sous-Direction Infrastructures et Services
Université de Lorraine.
Le 11/12/2020 à 20:41, Paul Mezzanini a écrit :
From how I understand it, that setting is a rev-limiter to prevent users from
creating HUGE sparse files and then wasting cluster resources firing off
deletes.
We have ours set to 32T and haven't seen any issues with large files.
--
Paul Mezzanini
Sr Systems Administrator / Engineer, Research Computing
Information & Technology Services
Finance & Administration
Rochester Institute of Technology
o:(585) 475-3245 | pfm...@rit.edu
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------------------------
________________________________________
From: Adam Tygart <mo...@ksu.edu>
Sent: Friday, December 11, 2020 1:59 PM
To: Mark Schouten
Cc: ceph-users; Patrick Donnelly
Subject: [ceph-users] Re: CephFS max_file_size
I've had this set to 16TiB for several years now.
I've not seen any ill effects.
--
Adam
On Fri, Dec 11, 2020 at 12:56 PM Patrick Donnelly <pdonn...@redhat.com> wrote:
Hi Mark,
On Fri, Dec 11, 2020 at 4:21 AM Mark Schouten <m...@tuxis.nl> wrote:
There is a default limit of 1TiB for the max_file_size in CephFS. I altered
that to 2TiB, but I now got a request for storing a file up to 7TiB.
I'd expect the limit to be there for a reason, but what is the risk of setting
that value to say 10TiB?
There is no known downside. Let us know how it goes!
--
Patrick Donnelly, Ph.D.
He / Him / His
Principal Software Engineer
Red Hat Sunnyvale, CA
GPG: 19F28A586F808C2402351B93C3301A3E258DD79D
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--
Cordialement,
Frédéric Nass
Direction du Numérique
Sous-Direction Infrastructures et Services
Université de Lorraine.
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