Chapter 13. Crimson (Technology Preview)

Procedure

1. While bootstrapping, use the --image flag to use Crimson build.

   Example

   [root@host 01 ~]# cephadm --image quay.ceph.io/ceph-ci/ceph:b682861f8690608d831f58603303388dd7915aa7-crimson bootstrap --mon-ip 10.1.240.54 --allow-fqdn-hostname --initial-dashboard-password Ceph_Crims

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2. Log in to the cephadm shell:

   Example

   [root@host 01 ~]# cephadm shell

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3. Enable Crimson globally as an experimental feature.

   Example

   [ceph: root@host01 /]# ceph config set global 'enable_experimental_unrecoverable_data_corrupting_features' crimson

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   Crimson is in a technology preview stage and is not suitable for production use.

4. Enable the OSD Map flag.

   Example

   [ceph: root@host01 /]# ceph osd set-allow-crimson --yes-i-really-mean-it

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   The monitor allows crimson-osd to boot only with the --yes-i-really-mean-it flag.

5. Enable Crimson parameter for the monitor to direct the default pools to be created as Crimson pools.

   Example

   [ceph: root@host01 /]#  ceph config set mon osd_pool_default_crimson true

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   The crimson-osd does not initiate placement groups (PG) for non-crimson pools.

6. Configure CPU allocation according the the resources available.

Procedure

1. Install libnbd and compile FIO:

   Example

   [root@host01 ~]# dnf install libnbd
   [root@host01 ~]# git clone git://git.kernel.dk/fio.git
   [root@host01 ~]# cd fio
   [root@host01 ~]# ./configure --enable-libnbd
   [root@host01 ~]# make

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2. Build crimson-store-nbd:

   Example

   [root@host01 ~]# cd build
   [root@host01 ~]# ninja crimson-store-nbd

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3. Run the crimson-store-nbd server with a block device. Specify the path to the raw device, like /dev/nvme1n1:

   Example

   [root@host01 ~]# export disk_img=/tmp/disk.img
   [root@host01 ~]# export unix_socket=/tmp/store_nbd_socket.sock
   [root@host01 ~]# rm -f $disk_img $unix_socket
   [root@host01 ~]# truncate -s 512M $disk_img
   [root@host01 ~]# ./bin/crimson-store-nbd \
     --device-path $disk_img \
     --smp 1 \
     --mkfs true \
     --type transaction_manager \
     --uds-path ${unix_socket} &
    --smp is the CPU cores.
   --mkfs initializes the device first.
   --type is the backend.

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4. Create an FIO job named nbd.fio:

   Example

   [global]
   ioengine=nbd
   uri=nbd+unix:///?socket=${unix_socket}
   rw=randrw
   time_based
   runtime=120
   group_reporting
   iodepth=1
   size=512M
   
   [job0]
   offset=0

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5. Test the Crimson object with the FIO compiled:

   Example

   [root@host01 ~]# ./fio nbd.fio

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Procedure

1. From the main branch and the topic branch, run make crimson osd:

   Example

   [root@host01 ~]# git checkout master
   [root@host01 ~]# make crimson-osd
   [root@host01 ~]# ../src/script/run-cbt.sh --cbt ~/dev/cbt -a /tmp/baseline ../src/test/crimson/cbt/radosbench_4K_read.yaml
   [root@host01 ~]# git checkout topic
   [root@host01 ~]# make crimson-osd
   [root@host01 ~]# ../src/script/run-cbt.sh --cbt ~/dev/cbt -a /tmp/yap ../src/test/crimson/cbt/radosbench_4K_read.yaml

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2. Compare the test results:

   Example

   [root@host01 ~]# ~/dev/cbt/compare.py -b /tmp/baseline -a /tmp/yap -v

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