This document is for a development version of Ceph.

ceph-syn -- ceph synthetic workload generator


ceph-syn [ -m monaddr:port ] --syn command


ceph-syn is a simple synthetic workload generator for the Ceph distributed file system. It uses the userspace client library to generate simple workloads against a currently running file system. The file system need not be mounted via ceph-fuse(8) or the kernel client.

One or more --syn command arguments specify the particular workload, as documented below.



Detach from console and daemonize after startup.

-c ceph.conf, --conf=ceph.conf

Use ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to determine monitor addresses during startup.

-m monaddress[:port]

Connect to specified monitor (instead of looking through ceph.conf).

--num_client num

Run num different clients, each in a separate thread.

--syn workloadspec

Run the given workload. May be specified as many times as needed. Workloads will normally run sequentially.


Each workload should be preceded by --syn on the command line. This is not a complete list.

mknap path snapname

Create a snapshot called snapname on path.

rmsnap path snapname

Delete snapshot called snapname on path.

rmfile path

Delete/unlink path.

writefile sizeinmb blocksize

Create a file, named after our client id, that is sizeinmb MB by writing blocksize chunks.

readfile sizeinmb blocksize

Read file, named after our client id, that is sizeinmb MB by writing blocksize chunks.

rw sizeinmb blocksize

Write file, then read it back, as above.

makedirs numsubdirs numfiles depth

Create a hierarchy of directories that is depth levels deep. Give each directory numsubdirs subdirectories and numfiles files.


Recursively walk the file system (like find).


ceph-syn is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at for more information.

See also

ceph(8), ceph-fuse(8)

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