Manually benchmarking OSDs

To manually benchmark a Ceph OSD, any existing benchmarking tool, for example Fio, can be used. Regardless of the tool or command used, steps documented here remain the same.

Important: The number of shards and BlueStore throttle parameters have an impact on the mClock operation queues. Therefore, it is critical to set these values carefully in order to maximize the impact of the mclock scheduler. For more information on these values, see factors that impact mClock operation queues.

Note: The steps in this section are only necessary if you want to override the Ceph OSD capacity determined automatically during the OSD initialization.

If you have already determined the benchmark data and wish to manually override the maximum OSD capacity for a Ceph OSD, see Specifying maximum OSD capacity.

Prerequisites

A running IBM Storage Ceph cluster.
Root-level access to the Ceph Monitor host.

Procedure

Log into the cephadm shell:

Example
```
[root@host01 ~]# cephadm shell
```

Benchmark a Ceph OSD:

Syntax

ceph tell osd.OSD_ID bench [TOTAL_BYTES] [BYTES_PER_WRITE] [OBJ_SIZE] [NUM_OBJS]

where:

TOTAL_BYTES: Total number of bytes to write.
BYTES_PER_WRITE: Block size per write.
OBJ_SIZE: Bytes per object.
NUM_OBJS: Number of objects to write.

Example

[ceph: root@host01 /]# ceph tell osd.0 bench 12288000 4096 4194304 100
{
    "bytes_written": 12288000,
    "blocksize": 4096,
    "elapsed_sec": 1.3718913019999999,
    "bytes_per_sec": 8956977.8466311768,
    "iops": 2186.7621695876896
}