How Can OpenNebula Fit Your Needs: A European Project Feedback

How can OpenNebula fit your needs ?

Or “I want to write my own (transfer) managers.”

Maxence Dunnewind

OpenNebulaConf 2013 - Berlin

24 - 26 Sept. 2013

Maxence Dunnewind - OpenNebulaConf2

Who am I ?

● French system engineer

● Working at Inria on BonFIRE european project● Working with OpenNebula inside BonFIRE

● Free software addict

● Puppet, Nagios, Git, Redmine, Jenkins, etc ...● Sysadmin of french Ubuntu community ( http://www.ubuntu-fr.org )

● More about me at:● http://www.dunnewind.net (fr) ● http://www.linkedin.com/in/maxencedunnewind

24 - 26 Sept. 2013


What's BonFIRE ?

European project which aims at delivering :

« … a robust, reliable and sustainable facility for large scale experimentally-driven cloud research. »

● Provide extra set of tools to help experimenters :

● Improved monitoring● Centralized services with common API for all testbeds

● OpenNebula project is involved in BonFIRE

● 4 testbeds provide OpenNebula infrastructure

24 - 26 Sept. 2013


What's BonFIRE … technically ?

● OCCI used through the whole stack

● Monitoring data :

● collected through Zabbix

● On-request export of metrics to experimenters

● Each testbed has a local administrative domain :

● Choice of technologies

● Open Access available !

● http://www.bonfire-project.eu

● http://doc.bonfire-project.eu

24 - 26 Sept. 2013


OpenNebula & BonFIRE

● Only use OCCI API

● Patched for BonFIRE

● Publish on Message Queue through hooks

● Handle “experiment” workflow :

● Short experiment lifetime

● Lot of VM to deploy in short time

● Only a few different images :● ~ 50● 3 based images used most of the time

24 - 26 Sept. 2013


Testbed infrastructure

● One disk server :

● 4 TB RAID-5 on 8 600GB SAS 15k hard drive

● 48 Gb of RAM

● 1 * 6 cores E5-2630

● 4 * 1 Gb Ethernet links aggregated using Linux bonding 802.3ad

● 4 workers :

● Dell C6220, 1 blade server with 4 blades

● Each blade has :● 64G of RAM ● 2 * 300G SAS 10k (grouped in one LVM VG)● 2 * E5-2620● 2 * 1Gb Ethernet aggregated

24 - 26 Sept. 2013


Testbed infrastructure

● Drawbacks :

● Not a lot of disk

● Not a lot of time to deploy things like Ceph backend

● Network is fine, but still Ethernet (no low-latency network)

● Only a few servers for VM

● Disk server is shared with other things (backup for example)

● Advantages :

● Network not heavily used

● Disk server is fine for virtualization

● Workers have a Xen with LVM backend

● Both server and workers have enough RAM to benefits of big caches

24 - 26 Sept. 2013


First iteration

● Pros :

● Fast boot process when image is already copied

● Network saving

● Cons :

● LVM snapshot performance

● Cache coherency

● Custom Housekeeping scripts need to be maintained

● Before the blade, we had 8 small servers :

● 4G of RAM● 500G of disk space● 4 cores●

● Our old setup customized SSH TM to :

● Make a local copy of each image on the host● Snapshot the local copy to boot the VM on it

24 - 26 Sept. 2013


Second iteration

● Requirements :

● Efficient copy through network

● ONE frontend hosted on the disks server as a VM

● Use of LVM backend (easy for backup / snapshot etc …)

● Try to benefits from cache when copying one image many times in a row

● Efficient use of network bonding when deploying on blades

● No copy if possible when image is persistent

But :

● OpenNebula doesn't support Copy + LVM backend (only ssh OR clvm)

● OpenNebula main daemon is written in compiled language (C/C++)

● But all mads are written in shell (or ruby ) !

● Creating a mad is just a new directory with a few shell files

24 - 26 Sept. 2013


What's wrong ?

● What's wrong with SSH TM :

● It uses ssh … which drops the performances

● Images need to be present inside the frontend VM to be copied, so a deployment will need to :

disk VM memory network→ → →● One ssh connection need to be opened for each transfer

● Reduce the benefits of cache● No cache on client/blade side

● What's wrong with NFS TM :

● Almost fine if you have very strong network / hard drives

● Disastrous when you try to do something with VMs if you don't have strong network / hard drives :)

24 - 26 Sept. 2013


Let's customize !

● Let's create our own Transfer Manager mad :

● Used for image transfer

● Only need a few files in (for system-wide install)

/var/lib/one/remotes/tm/mynewtm ● clone => Main script called to copy an OS image to the node● context => Manage context ISO creation and copy● delete => Delete OS image● ln => Called when a persistent (not cloned) image is used in a VM

Only clone, delete and context will be updated, ln is the same as the NFS one

24 - 26 Sept. 2013


Let's customize !

How can we improve ?

● Avoid SSH to improve copy● Netcat ?

● Require complex script to create netcat server dynamically ● NFS ?

● Avoid to run ssh commands if possible

● Try to improve cache use● On server ● On clients / blades

● Optimize network for parallel copy● Blade IP's need to be carefully chosen to use one 1Gb link of disk server for each blade ( 4 links, 4 blades )

24 - 26 Sept. 2013


Infrastructure setup

● Disk server acts has NFS server

● Datastore is exported from the disk server as a NFS share :● To the ONE frontend (VM on the same host)● To the blades (through network)

● Each blade mounts the datastore directory locally

● Copy of base images is done from NFS mount to local LVM

● Or linked in case of persistent image => only persistent images write directly on NFS

● Almost all commands are done directly on NFS share for VM deployment

● No extra ssh sessions

24 - 26 Sept. 2013


Deployment Workflow

Using default SSH

● Ssh mkdir

● Scp image

● Ssh mkdir for context

● Create context iso locally

● Scp context iso

● Ssh create symlink

● Remove local context iso / directory

Using custom TM

● Local mkdir on NFS mount

● Create LV on worker

● Ssh to cp image from NFS to local LV

● Create symlink on NFS mount which points to LV

● Create context iso on NFS mount

24 - 26 Sept. 2013


Deployment Workflow

Using default SSH

● 3 SSH connections

● 2 encrypted copy

● ~ 15MB/s raw bw

● No improvement on next copy

● ~ 15MB for real image copy => ssh makes encryption / cpu the bottleneck

Using custom TM

● 1 SSH connection

● 0 encrypted copy

● 2 copy from NFS :● ~ 110MB/s raw bw for first copy ( > /dev/null)● up to ~120MB/s raw for second● ~ 80MB/s for real image copy

● Bottleneck is hard drive● Up to 115 MB/s with cache

24 - 26 Sept. 2013


Results

Deploying a VM using our most commonly used image (700M) :

● Scheduler interval is 10s, and can deploy 30 VMs per run, 3 per host

● Takes ~ 13s from ACTIVE to RUNNING

● Image copy ~ 7s

Tue Sep 24 22:51:11 2013 [TM][I]: 734003200 bytes (734 MB) copied, 6.49748 s, 113 MB/s'

● 4 VMs on 4 nodes (one per node) from submission to RUNNING in 17 s , 12 VMs in 2 minutes 6s (+/- 10s)

● Transfer between 106 and 113 MB/s on the 4 nodes at same time● Thanks to efficient 802.3ad bonding

24 - 26 Sept. 2013


Results

24 - 26 Sept. 2013


Conclusion

With no extra hardware, just updating 3 scripts in ONE and our network configuration, we :

● Reduced contention on SSH, speedup command doing them locally (NFS then sync with nodes)

● Reduced CPU used by deployment for SSH encryption

● Removed SSH bottleneck on encryption

● Improved almost by 8 our deployment time

● Optimized parallel deployment, so that we reach (network) hardware limitation :

● Deploying images in parallel have almost no impact on each deployment performance

All this without need for a huge (and expensive) NFS server (and network) which would have to host images of running VMs !

Details on http://blog.opennebula.org/?p=4002

The END ….The END ….

Thanks for your attention !

Maxence Dunnewind

OpenNebulaConf 2013 - Berlin

How Can OpenNebula Fit Your Needs: A European Project Feedback

Technology

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