Docker on OS disk VS docker on dedicated disk

Question

We have 57 rhel servers machines – with version 7.5

The machines have strong HW as 128G memory and 32 CPU ,

We planed to install docker service on all machines , in order to run couple containers on docker

We are before the following dilemma

We can install the docker directly on OS disk – sda , so /var/lib/docker will be folder on the OS

Or

To add dedicated disk - sdb for the docker in order to run the docker on the sdb disk that isn't the OS disk ,

for example add new disk – sdb and mount the sdb to /var/lib/docker

Is it justified to add additional dedicated disk as sdb for the docker, in order to avoid performances Aspects From OS/disk/Docker side ?

the server are part of Hadoop cluster , for example DATA-NODE servers that contain the HDFS disks + and kafka machines + servers that mange the HDFS and TARN resources , etc — King David, Aug 13 '20 at 11:49
@ Michael Hampton , let me know if you need additional info ? — King David, Aug 13 '20 at 12:37

score 2 · Accepted Answer · answered Aug 13 '20 at 13:47

Short answer

No, the performance toll in such a big server should be negligible (and could be neutered in case things go south).

Long answer

It depends on how your docker is configured and what you're running inside your containers. From a disk perspective, we can separate the docker influence over three key aspects:

Disk usage for images and logs (as volumes are not bound to the /var/lib/docker)
Mount points and inode usage (depending on which storage driver you're using).
Read/write usage for the software inside the docker container (which is something that is not really docker's fault).

For the first two, you can set different configurations so it won't be too aggressive on the disk (cleaning old images frequently, setting size limits for the logs, changing parameters for the storage driver, etc).

As for the third, it depends solely on how the docker image behaves regarding the disk usage, and even then you can easily override the behaviour by using volumes on different devices.

ok lets say the OS disk I/O utilization isn't high , then we can say for sure that add additional disk for docker isn't necessary ? — King David, Aug 13 '20 at 14:02
Shouldn't be necessary. Don't forget to watch out for space as well. — Gustavo Kawamoto, Aug 13 '20 at 14:49
what you mean the space ? , ( we have /var 120G ) , do you mean about the /var? ( since docker files are under - /var/lib/docker ) — King David, Aug 13 '20 at 15:04

Docker on OS disk VS docker on dedicated disk

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