[Gluster-users] gluster 5.11 issue: Endless performing entry selfheal / Completed entry selfheal on the same pending heal files after server reboot + very high load
Artem Russakovskii
archon810 at gmail.com
Sun Apr 26 22:13:01 UTC 2020
Hi all,
I've been observing this problem for a long time now and it's time to
finally figure out what's going on.
We're running gluster 5.11 and have a 10TB 1 x 4 = 4 replicate volume. I'll
include its slightly redacted config below.
When I reboot one of the servers and it goes offline for a bit, when it
comes back, heal info tells me there are some files and dirs that are "heal
pending". 0 "split-brain" and "possibly healing" - only "heal pending"
are >0.
1. For some reason, the server that was rebooted shows "heal pending" 0.
All other servers show "heal pending" with some number, say 65.
2. We have cluster.self-heal-daemon enabled.
3. The logs are full of "performing entry selfheal" and "completed entry
selfheal" messages that continue to print endlessly.
4. This "heal pending" number never goes down by itself, but it does if
I run some operation on it, like md5sum.
5. When the server goes down for reboot and especially when it comes
back, the load on ALL servers shoots up through the roof (load of 100+) and
ends up bringing everything down, including apache and nginx. My theory is
that self-heal kicks in so hard that it kills IO on these attached Linode
block devices. However, after some time - say 10 minutes - the load
subsides, but the "heal pending" remains and the gluster logs continue to
output "performing entry selfheal" and "completed entry selfheal" messages.
This load spike has become a huge issue for us because it brings down the
whole site for entire minutes.
6. At this point in my investigation, I noticed that the
selfheal messages actually repeat for the same gfids over and over.
[2020-04-26 21:32:29.877987] I [MSGID: 108026]
[afr-self-heal-entry.c:897:afr_selfheal_entry_do] 0-SNIP_data1-replicate-0:
performing entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc
[2020-04-26 21:32:29.901246] I [MSGID: 108026]
[afr-self-heal-common.c:1729:afr_log_selfheal] 0-SNIP_data1-replicate-0:
Completed entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc. sources=
sinks=0 1 2
[2020-04-26 21:32:32.171959] I [MSGID: 108026]
[afr-self-heal-entry.c:897:afr_selfheal_entry_do] 0-SNIP_data1-replicate-0:
performing entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc
[2020-04-26 21:32:32.225828] I [MSGID: 108026]
[afr-self-heal-common.c:1729:afr_log_selfheal] 0-SNIP_data1-replicate-0:
Completed entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc. sources=
sinks=0 1 2
[2020-04-26 21:32:33.346990] I [MSGID: 108026]
[afr-self-heal-entry.c:897:afr_selfheal_entry_do] 0-SNIP_data1-replicate-0:
performing entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc
[2020-04-26 21:32:33.374413] I [MSGID: 108026]
[afr-self-heal-common.c:1729:afr_log_selfheal] 0-SNIP_data1-replicate-0:
Completed entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc. sources=
sinks=0 1 2
7. I used gfid-resolver.sh from https://gist.github.com/4392640.git to
resolve this gfid to the real location and yup - it was one of the files (a
dir actually) listed as "heal pending" in heal info. As soon as I ran
md5sum on the file inside (which was also listed in "heal pending"), the
log messages stopped repeating for this entry and it disappeared from "heal
pending" heal info. These were the final log lines:
[2020-04-26 21:32:35.642662] I [MSGID: 108026]
[afr-self-heal-metadata.c:52:__afr_selfheal_metadata_do]
0-SNIP_data1-replicate-0: performing metadata selfheal on
96d282cf-402f-455c-9add-5f03c088a1bc
[2020-04-26 21:32:35.658714] I [MSGID: 108026]
[afr-self-heal-common.c:1729:afr_log_selfheal] 0-SNIP_data1-replicate-0:
Completed metadata selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc.
sources=0 [1] 2 sinks=3
[2020-04-26 21:32:35.686509] I [MSGID: 108026]
[afr-self-heal-entry.c:897:afr_selfheal_entry_do] 0-SNIP_data1-replicate-0:
performing entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc
[2020-04-26 21:32:35.720387] I [MSGID: 108026]
[afr-self-heal-common.c:1729:afr_log_selfheal] 0-SNIP_data1-replicate-0:
Completed entry selfheal on 96d282cf-402f-455c-9add-5f03c088a1bc. sources=0
[1] 2 sinks=3
I have to repeat this song and dance every time I reboot servers and run
md5sum on each "heal pending" file or else the messages will continue
presumably indefinitely. In the meantime, the files seem to be fine when
accessed.
What I don't understand is:
1. Why doesn't gluster just heal them properly instead of getting stuck?
Or maybe this was fixed in v6 or v7, which I haven't upgraded to due to
waiting for another unrelated issue to be fixed?
2. Why does heal info show 0 "heal pending" files on the server that was
rebooted, but all other servers show the same number of "heal pending"
entries >0?
3. Why are there these insane load spikes upon going down and especially
coming back online? Is it related to the issue here? I'm pretty sure that
it didn't happen in previous versions of gluster, when this issue didn't
manifest - I could easily bring down one of the servers without it creating
havoc when it comes back online.
Here's the volume info:
Volume Name: SNIP_data1
Type: Replicate
Volume ID: 11ecee7e-d4f8-497a-9994-ceb144d6841e
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 4 = 4
Transport-type: tcp
Bricks:
Brick1: SNIP:/mnt/SNIP_block1/SNIP_data1
Brick2: SNIP:/mnt/SNIP_block1/SNIP_data1
Brick3: SNIP:/mnt/SNIP_block1/SNIP_data1
Brick4: SNIP:/mnt/SNIP_block1/SNIP_data1
Options Reconfigured:
performance.client-io-threads: on
nfs.disable: on
transport.address-family: inet
cluster.self-heal-daemon: enable
performance.cache-size: 1GB
cluster.lookup-optimize: on
performance.read-ahead: off
client.event-threads: 4
server.event-threads: 4
performance.io-thread-count: 32
cluster.readdir-optimize: on
features.cache-invalidation: on
features.cache-invalidation-timeout: 600
performance.stat-prefetch: on
performance.cache-invalidation: on
performance.md-cache-timeout: 600
network.inode-lru-limit: 500000
performance.parallel-readdir: on
performance.readdir-ahead: on
performance.rda-cache-limit: 256MB
network.remote-dio: enable
network.ping-timeout: 5
cluster.quorum-type: fixed
cluster.quorum-count: 1
cluster.granular-entry-heal: enable
cluster.data-self-heal-algorithm: full
Appreciate any insight. Thank you.
Sincerely,
Artem
--
Founder, Android Police <http://www.androidpolice.com>, APK Mirror
<http://www.apkmirror.com/>, Illogical Robot LLC
beerpla.net | @ArtemR <http://twitter.com/ArtemR>
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