[MooseFS-Users] Metadata server using unexpectedly large amount of RAM

[Alex C. <ac...@in...>]

Hi,

We have two installations, one cluster on PRO and one on free version
(for backups). This problem affects the backup cluster (a pair of
servers, replica 2).

On the PRO cluster, I have:

total space 	avail space 	trash space 	trash files 	sustained space
sustained files 	all fs objects 	directories 	files 	chunks 	all chunk
copies 	regular chunk copies
86 TiB 	56 TiB 	1.0 GiB 	2324 	0 B 	0 	61381852 	2984334 	58397444
58053021 	116106090 	116106090


and usage:

# 	ip 	version 	state 	metadata version 	RAM used 	CPU used 	last
successful metadata save 	last metadata save duration 	last metadata
save status 	exports checksum
1 	172.16.41.202 	3.0.73 PRO 	LEADER 	1 513 203 176 	19 GiB
all:10.34% sys:1.38% user:8.96% 	Tue Mar 29 01:02:42 2016 	~2.7m
Downloaded from other master 	E5ABFEBB6AB52D4A
2 	192.168.22.19 	3.0.73 PRO 	FOLLOWER 	1 513 203 176 	17 GiB
all:0.65% sys:0.55% user:0.10% 	Tue Mar 29 18:00:30 2016 	~30.0s 	Saved
in background 	E5ABFEBB6AB52D4A


On the backup cluster, I have:

total space 	avail space 	trash space 	trash files 	sustained space
sustained files 	all fs objects 	directories 	files 	chunks 	all chunk
copies 	regular chunk copies
0 B 	0 B 	158 GiB 	88697 	0 B 	0 	80913065 	11751374 	69051819
70046972 	127354504 	127354504


and usage:

# 	ip 	version 	state 	metadata version 	RAM used 	CPU used 	last
successful metadata save 	last metadata save duration 	last metadata
save status 	exports checksum
1 	172.16.26.20 	3.0.74 	- 	2 025 942 120 	39 GiB
all:12.85% sys:7.07% user:5.78% 	Tue Mar 29 18:01:12 2016 	~1.2m 	Saved
in background 	E5ABFEBB6AB52D4A


As you can see, the backup cluster (free version) uses much more RAM per
file than the main, Pro cluster. I did have some previous problems after
attempting snapshots of the whole MooseFS tree where reports stated I
had over 240,000,000 files (!) but on removing the snapshot the file
number went back to normal.

Any ideas? I can send a metadata file via scp if required.

Best regards

Alex

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