[Pulp-list] Long upgrade times from 2.6 -> 2.8
Ashby, Jason (IMS)
AshbyJ at imsweb.com
Sun Jul 3 12:25:33 UTC 2016
Yeah our content is on NFS mounts backed by regular non-SSD disks, so IO is pretty crappy. But its cheap and perfect for serving yum content.
My recommendation would be having pulp-manage-db spit out a message before each big migration that says “this next migration is a big deal!” that would be a nice fyi. And perhaps a URL to see migration details. This doesn’t prep people ahead of time to schedule downtime, but at least keeps them from thinking something is wrong.
From: pulp-list-bounces at redhat.com [mailto:pulp-list-bounces at redhat.com] On Behalf Of Michael Hrivnak
Sent: Friday, July 01, 2016 4:19 PM
To: Eric Helms <ehelms at redhat.com>
Cc: pulp-list <pulp-list at redhat.com>
Subject: Re: [Pulp-list] Long upgrade times from 2.6 -> 2.8
I expect the performance will be highly dependent on disk access speed. Latency is far more important than throughput for those two migrations. Deployments using NFS for example may benefit from finding ways to reduce latency during the migration; there may be mount options that can be adjusted only while the migration runs, or perhaps the code itself can be run on a machine closer to the data than where pulp usually runs.
Michael
On Fri, Jul 1, 2016 at 11:53 AM, Eric Helms <ehelms at redhat.com<mailto:ehelms at redhat.com>> wrote:
My main worry or first check I wanted to put to rest was that it was an actual issue. Given that everything is sane, I think warning users that upgrades will scale with the amount of content and giving them some rough estimates based on other users data is the best option. That way they can at least prepare themselves with knowledge for planning their upgrade outages.
Thanks for looking into this so quickly,
Eric
On Fri, Jul 1, 2016 at 11:50 AM, Brian Bouterse <bbouters at redhat.com<mailto:bbouters at redhat.com>> wrote:
With 2.8 specifically there is a *lot* of work done by the migrations and the runtime should scale with the content size. In other words I don't think it's doing useless work, there is just a lot of it.
I just did a quick audit of the two major offending migrations and they are implemented sanely so I don't think there is a quick fix to improve the runtime.
I believe to get a shorter runtime we would have to parallelize the migrations.
Regarding things going wrong, we do assume that migrations should be re-entrant meaning that if for some reason something strange occurs it should always be safe to run pulp-manage-db and it will pick up where it left off. Just a behavioral FYI.
These migration with 2.8 should not be norm, so I don't expect this to be very common in the future until maybe a major release (3.0).
Given all ^, what do you think we should do?
-Brian
On 07/01/2016 11:23 AM, Eric Helms wrote:
I think there are a couple of considerations.
1) The first issue is that a 6-18 hour upgrade window is not something
users expect and we've not been warning them of such so they can plan an
outage accordingly. Lengthy upgrades also have that tendency to make
users feel something is wrong or increase the risk that something can go
wrong in between.
2) The fundamental question of - is this a bug or does this make
perfect sense and how it has to work?
3) Applying the upgrade on an existing 2.6 if it changed nothing of the
environment could work, the tough part is having to distribute that
backwards. Pulp would have to distribute it back to 2.6, and Katello
would have to push out patches to our 2.4 release channel.
Eric
On Fri, Jul 1, 2016 at 11:14 AM, Brian Bouterse <bbouters at redhat.com<mailto:bbouters at redhat.com>
<mailto:bbouters at redhat.com<mailto:bbouters at redhat.com>>> wrote:
I'm trying to understand if the pain point is related to downtime or
total runtime.
For instance, what if these migration could be run as a
pre-migration step, ahead of time while Pulp was still online? The
upgrade would still take just as long but you could use your (in
this case) 2.6 install normally while the migrations are applying.
Once they are done then the actual upgrade of the codebase could be
very short.
-Brian
On 07/01/2016 09:20 AM, Eric Helms wrote:
On Fri, Jul 1, 2016 at 8:52 AM, Ashby, Jason (IMS)
<AshbyJ at imsweb.com<mailto:AshbyJ at imsweb.com> <mailto:AshbyJ at imsweb.com<mailto:AshbyJ at imsweb.com>>
<mailto:AshbyJ at imsweb.com<mailto:AshbyJ at imsweb.com> <mailto:AshbyJ at imsweb.com<mailto:AshbyJ at imsweb.com>>>> wrote:
FWIW I just upgraded from 2.7 -> 2.8 and it was approx. 1-2 hr
upgrade to get through the migrations in pulp-manage-db.____
__ __
290 GB /var/lib/pulp____
16 GB MongoDB____
__ __
*From:*pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>
<mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>>
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<mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>>>
[mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>
<mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>>
<mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>
<mailto:pulp-list-bounces at redhat.com<mailto:pulp-list-bounces at redhat.com>>>] *On Behalf Of *Michael
Hrivnak
*Sent:* Friday, July 01, 2016 8:31 AM
*To:* Eric Helms <ehelms at redhat.com<mailto:ehelms at redhat.com>
<mailto:ehelms at redhat.com<mailto:ehelms at redhat.com>> <mailto:ehelms at redhat.com<mailto:ehelms at redhat.com>
<mailto:ehelms at redhat.com<mailto:ehelms at redhat.com>>>>
*Cc:* pulp-list <pulp-list at redhat.com<mailto:pulp-list at redhat.com>
<mailto:pulp-list at redhat.com<mailto:pulp-list at redhat.com>> <mailto:pulp-list at redhat.com<mailto:pulp-list at redhat.com>
<mailto:pulp-list at redhat.com<mailto:pulp-list at redhat.com>>>>
*Subject:* Re: [Pulp-list] Long upgrade times from 2.6 ->
2.8____
__ __
Did you get any feedback on whether one particular migration
seemed
to be running for a lot of that time?
For the 1.5TB/100GB MongoDB scenario here is what I am able to glean
from user logs (which I can share privately with anyone debugging):
~5 hours: Applying pulp_puppet.plugins.migrations version 4
~10 hours: Applying pulp_rpm.plugins.migrations version 28
Use reports "lots of stating, unlinking, and linking of all the
symlinks
in /var/lib/pulb" if that helps.
Another user reports ~6 hours on 176G of data.
Eric
____
__ __
Michael____
__ __
On Fri, Jul 1, 2016 at 7:23 AM, Eric Helms
<ehelms at redhat.com<mailto:ehelms at redhat.com> <mailto:ehelms at redhat.com<mailto:ehelms at redhat.com>>
<mailto:ehelms at redhat.com<mailto:ehelms at redhat.com> <mailto:ehelms at redhat.com<mailto:ehelms at redhat.com>>>>
wrote:____
Howdy,____
__ __
We (Katello) have had users reporting incredibly long
upgrade
times when upgrading from 2.6 to 2.8. This occurs during the
pulp-manage-db step that is run as the beginning of our
installers upgrade process. Based on the numbers below, does
this make sense at all?____
__ __
Some numbers:____
__ __
18 hour upgrade____
1.5 TB /var/lib/pulp____
100GB MongoDB____
__ __
__ __
Thanks,____
Eric____
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