[Gluster-users] 3.7.16 with sharding corrupts VMDK files when adding and removing bricks

Pranith Kumar Karampuri pkarampu at redhat.com
Mon Nov 14 11:20:44 UTC 2016

On Mon, Nov 14, 2016 at 4:38 PM, Gandalf Corvotempesta <
gandalf.corvotempesta at gmail.com> wrote:

> 2016-11-14 11:50 GMT+01:00 Pranith Kumar Karampuri <pkarampu at redhat.com>:
> > To make gluster stable for VM images we had to add all these new features
> > and then fix all the bugs Lindsay/Kevin reported. We just fixed a
> corruption
> > issue that can happen with replace-brick which will be available in 3.9.0
> > and 3.8.6. The only 2 other known issues that can lead to corruptions are
> > add-brick and the bug you filed Gandalf. Krutika just 5 minutes back saw
> > something that could possibly lead to the corruption for the add-brick
> bug.
> > Is that really the Root cause? We are not sure yet, we need more time.
> > Without Lindsay/Kevin/David Gossage's support this workload would have
> been
> > in much worse condition. These bugs are not easy to re-create thus not
> easy
> > to fix. At least that has been Krutika's experience.
> Ok, but this changes should be placed in a "test" version and not
> marked as stable.
> I don't see any development release, only stable releases here.
> Do you want all features ? Try the "beta/rc/unstable/alpha/dev" version.
> Do you want the stable version without known bugs but slow on VMs
> workload? Use the "-stable" version.
> If you relase as stable, users tend to upgrade their cluster and use
> the newer feature (that you are marking as stable).
> What If I upgrade a production cluster to a stable version and try to
> add-brick that lead to data corruption ?
> I have to restore terabytes worth of data? Gluster is made for
> scale-out, what I my cluster was made with 500TB of VMs ?
> Try to restore 500TB from a backup....................
> This is unacceptable. add-brick/replace-brick should be common "daily"
> operations. You should heavy check these for regression or bug.

This is a very good point. Adding other maintainers.

> > One more take away is to get the
> > documentation right. Lack of documentation led Alex to try the worst
> > possible combo for storing VMs on gluster. So we as community failed in
> some
> > way there as well.
> >
> >       Krutika will be sending out VM usecase related documentation after
> > 28th of this month. If you have any other feedback, do let us know.
> Yes, lack of updated docs or a reference architecture is a big issue.

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