[MooseFS-Users] question about mfs reading speed slower than writing speed???

[Peter <new...@gm...>]

Hi moosefs team,

Recently, I setup a moosefs filesystem.
with the following topology:

Master server: 1
Mesta logger server: 1
chunkserver: 3

and each file will keep 3 copy.

base in this topology, I have run some test:

*and I find that write data to the mfs file system is much faster than the
reading speed, this test result is confusing me. can you guys explain a
little bit this for me?*


all the test file are the same size
/mnt/mfs --> moosefs file system.
/data  --> local disk
---------------------------------------------------------------------------------------------

[root@TENCENT64 /mnt/mfs]# time cp 111.iso /mnt/mfs/
cp: cannot stat `111.iso': No such file or directory

real    0m0.002s
user    0m0.000s
sys     0m0.000s
[root@TENCENT64 /mnt/mfs]# time cp /data/111.iso /mnt/mfs/

real    0m5.065s
user    0m0.000s
sys     0m0.316s
[root@TENCENT64 /mnt/mfs]# time cp 555.iso /data/

real    0m11.156s
user    0m0.000s
sys     0m0.780s
[root@TENCENT64 /mnt/mfs]# ^C
[root@TENCENT64 /mnt/mfs]# time cp 666.iso /data

real    0m11.165s
user    0m0.004s
sys     0m0.864s
[root@TENCENT64 /mnt/mfs]# time cp /data/555.iso /mnt/mfs/555-new.iso

real    0m5.045s
user    0m0.000s
sys     0m0.300s
[root@TENCENT64 /mnt/mfs]# ll -h
total 3.0G
-rw-r--r-- 1 root root 500M Apr 12 14:36 111.iso
-rw-r--r-- 1 root root 500M Apr 12 15:33 555-new.iso
-rw-r--r-- 1 root root 500M Apr 11 01:43 555.iso
-rw-r--r-- 1 root root 500M Apr 11 01:46 666.iso
-rw-r--r-- 1 root root 500M Apr 11 01:06 aaa.iso
-rw-r--r-- 1 root root 500M Apr 11 01:39 bbb.iso


also, i use another client server to run the test , (the client server in
other city)

we can see, the read speed is much more slow than the writing speed.

[root@Tencent-SNG /mnt/mfs]# time cp 111.iso /data/

real    0m44.736s
user    0m0.005s
sys     0m1.299s
[root@Tencent-SNG /mnt/mfs]# time cp /data/222.iso ./

[root@Tencent-SNG /data]# time cp 333.iso /mnt/mfs/333-new.iso

real    0m12.432s
user    0m0.008s
sys     0m0.614s

Also, in case there is some kernel or linux version problem,
I setup the moosefs master in centos 6.3 and centos 7.0.
still have the same problem.

I also search the internet , and find that, the other also have the same
problem.

Other people's performance test data:
Block size 1M Filesize20G
Client1 write：68.4MB/s  read：25.3MB/s
Client2 write：67.5MB/s  read：24.7MB/s