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OverlayFS on RedHat 7.4

(Javier Ramirez) #1

Hi all,
As RedHat supports now overlayfs on their latest release (REDHAT 7.4), will Docker Inc, support overlayfs as default driver for Docker Engine EE on RedHat hosts?.

Many Thanks In Advance,
Javier Ramírez

(Antoinetran) #2

Latest docker-ce 17.06 are already using overlayfs as default. Btw, overlayfs is not really production-ready compared to devicemapper (see issues of overlayfs).

(Javier Ramirez) #3

“When in doubt, the best all-around configuration is to use a modern Linux distribution with a kernel that supports the overlay2 storage drive”

devicemapper as a lot of issues regarding churn (intense container destroy/creation), am I wrong?.

(Antoinetran) #4

We use overlayfs, I don’t know if this is also called overlayfs2. But regarding devicemapper vs overlayfs, contrary to what docker devs says, we encountered at least 3 differents types of issues that we have never seen in devicemapper. devicemapper with direct-lvm is production-ready, according to docker official docs. Moreover, docker EE must use devicemapper, while docker CE can use both overlayfs and devicemapper… Why do you think docker EE stayed with devicemapper?

(Javier Ramirez) #5

Because redhat didn’t support overlayfs on their releases until 7.4?.
I think that underlying OS and its support still matters.
We really need a Docker supported os for containers, crossing fingers on linuxkit evolution.

(Goffinf) #6

We use RHEL 7.3 and more recently 7.4, and we use device-mapper thin provisioned volumes according to RHELs own recommendation. TBH we haven’t experienced any significant issues other than some of our own making (our anti-malware and intrusion detection software can hit IO pretty hard). We also recycle our hosts frequently as part of our hardening policy and as such they don’t stay around very long which might have a beneficial side effect I suppose. But anyway, device-mapper has been pretty stable for us although it is worth a look at overlayfs2 when it is supported. Do you know if Redhat have stated that as yet (I haven’t seen any recent announcements to that effect but could have missed it ?)

(Javier Ramirez) #7

As far as I know, there are many entries in RedHat Customer portal
asking about overlayfs support (for both versions)
(,,, for example). That’s why I
ask Docker for their point of view. If RedHat supports overlayfs, we
will need to know if Docker is going to change their support matrix for
RedHat engines.

(Goffinf) #8

Yes I’ve seen these and many others like it. But the question is better addressed to Redhat themselves rather than Docker. When I last looked, Redhat’s own docker install docs were still recommending device-mapper. So my question back at you was, have you seen anything official from Redhat that suggests that they both support and, possibly even recommend, use of overlayfs2 for RHEL 7.4 instances running docker (and not just their own distro) ?

(Javier Ramirez) #9

Sorry but I am not endorsed in any of them and I am just a Docker
professional and can’t speak about how they will support overlayfs. I am
not against devicemapper, it will work quite wellin many situations, but
you need to add extra knowledge abouth LVM thin provision and how to
manage its issues and tricks. Overlayfs (both versions) and AUFS have
better performance when executing many containers based on same layers.
Devicemapper instead, have extra value on container FS encapsulation,
but it’s not recommended when creating/destroying a lot of containers
because of defragmentation. As you said, you reinstall host quite often
and never had problems regarding host FS usage and performance. That’s
fine. I always said that devicemapper adds quite simple management tasks
(lvm tasks for recovering space) that users can execute often on a high
availability enviroment without problems.

(Needcool) #10
Here, docker ee is support by RHEL with overlay2

(Needcool) #11

Are you sure?

It is still exist on centos7.4 and docker-ce17.06