[Gluster-users] Several questions from replicas to performance

[Elías David]

Hello everyone,

The place I work for is starting to look at gluster to replace a current 
windows share we have. The amount of files and sizes varies a lot, from 
very small (~5kb) to somewhat large (~25GB).

Since we're checking if gluster is a viable option for us, and we're 
still learning about the filesystem, we're pretty sure that a problem 
we're seeing right now is coming from our ignorance.

Right now our biggest concern during our tests is a ridiculously low 
performance, I'm talking about a 'cp -R /home/user/* /mnt/data' where 
/mnt/data is: mount -t glusterfs 192.168.0.10:/VolName /mnt/data that 
took something ridiculous like 12 "hours" or more to transfer mere 226GB 
of data (from ISOs to documents to flat files....).

Right now our setup is this:
-We have 5 servers (peers) with each having two 2TB disks WD black 
formatted with xfs -i size=512, each disk is a brick so we have:

192.168.0.10 disk0 (2TB) on /gv0/vol1
192.168.0.10 disk1 (2TB) on /gv0/vol2
192.168.0.11 disk0 (2TB) on /gv0/vol1
192.168.0.11 disk1 (2TB) on /gv0/vol2
and so on...

Total: 2TB disk x 10 = 20TB

Now, not being really sure yet how replica counts really work, we 
created a volume with "replica 5", as in:

gluster vol create replica 5 server1:/gv0/vol1/data 
server2:/gv0/vol1/data server3:/gv0/vol1/data server4:/gv0/vol1/data 
server5:/gv0/vol1/data server1:/gv0/vol2/data server2:/gv0/vol2/data 
server3:/gv0/vol2/data server4:/gv0/vol2/data server5:/gv0/vol2/data

Vol info goes like this:

Volume Name: Data
Type: Distributed-Replicate
Volume ID: 2c938585-d2bd-43cf-98d8-caab70033750
Status: Started
Number of Bricks: 2 x 5 = 10
Transport-type: tcp
Bricks:
Brick1: 192.168.0.10:/gv0/vol1/data
Brick2: 192.168.0.11:/gv0/vol1/data
Brick3: 192.168.0.12:/gv0/vol1/data
Brick4: 192.168.0.13:/gv0/vol1/data
Brick5: 192.168.0.14:/gv0/vol1/data
Brick6: 192.168.0.10:/gv0/vol2/data
Brick7: 192.168.0.11:/gv0/vol2/data
Brick8: 192.168.0.12:/gv0/vol2/data
Brick9: 192.168.0.13:/gv0/vol2/data
Brick10: 192.168.0.14:/gv0/vol2/data

The servers are not bad really, Intel(R) Xeon(R) CPU X5450  @ 3.00GHz 8 
cores, 32 GB of ram and 1GB link for gluster

As I said earlier I mounted this vol on another machine in the lan using 
'mount -t glusterfs 192.168.0.10:/Data /mnt/data' and I use a simple cp 
-R to put data on it, I also tested with 'dd if=/dev/zero 
of=/mnt/data/zerofile bs=1M count=50000' and this dd process is running 
four about 5 hours now and I'm about to reach 24GB of 50GB file size...

I'm pretty sure that this problem is solely caused from our ignorance of 
the filesystem and that's why I ask you guys

The servers are all running CentOS 6.5, glusterfs-* packages from EPEL 
repo, glusterfs version 3.4.2

Another question I would like to add if I may is that, I run df -h after 
mounting the volume and I'm seeing as total volume capacity of 3.7 
terabytes when I expected something like 10 terabytes given 10 2TB disks 
in a replica 5 setup, is this normal or I'm misunderstanding the replica 
count thing?

That's it, sorry for the long message just wanted to be clear, any input 
or info about this would be greatly appreciated.

Thanks!