Please find the latest version of these slides at:

https://code.google.com/p/ganeti/wiki/LISA2013

• None-mirrored templates: plain, file
• Internally mirrored templates: drbd
• Externally mirrored templates: sharedfile, rbd, blockdev, diskless

• Instance disks residing inside an external SAN/NAS appliance visible by all Ganeti nodes (e.g. NetApp, EMC, IBM)
• Instances should be able to migrate/failover to any node that can access the appliance.
• Ganeti should integrate with external SAN/NAS appliances in a generic way, independent of the appliance itself in the easiest possible way from the admin's perspective.

• A simple interface inspired by the Ganeti OS interface
• To plug an appliance to Ganeti, we need a corresponding 'ExtStorage provider' which is a set of scipts residing under a directory.
• e.g. /usr/share/ganeti/extstorage/provider1/

Every ExtStorage provider should provide the following methods:

• Create a disk on the appliance
• Remove a disk from the appliance
• Grow a disk on the appliance
• Attach a disk to a given Ganeti node
• Detach a disk from a given Ganeti node
• SetInfo on a disk (add metadata)
• Verify the provider's supported parameters

The methods are implemented in the corresponding 7 executable scripts, using appliance-specific tools:

# ls -l /usr/share/ganeti/extstorage/provider1

create
remove
grow
attach
detach
setinfo
verify

attach returns a block device path on success

Input via environment variables, e.g. VOL_NAME, VOL_SIZE

• Introduce a new externally mirrored disk template: ext
• Introduce a new disk option: provider

Assuming two appliances visible by a Ganeti cluster and their two ExtStorage providers installed on all Ganeti nodes:

/usr/share/ganeti/extstorage/emc/*
/usr/share/ganeti/extstorage/ibm/*

# gnt-instance add -t ext --disk=0:size=2G,provider=emc

# gnt-instance add -t ext --disk=0:size=2G,provider=emc \
                          --disk=1:size=1G,provider=emc \
                          --disk=2:size=10G,provider=ibm

# gnt-instance modify --disk 3:add,size=20G,provider=ibm

# gnt-instance migrate testvm1

# gnt-instance migrate n- nodeX.example.com testvm1

Support for dynamic passing of arbitrary parameters to ExtStorage providers during instance creation/modification per-disk:

# gnt-instance add -t ext --disk=0:size=2G,provider=emc,param1=value1,param2=value2
                          --disk=1:size=10G,provider=ibm,param3=value3,param4=value4

# gnt-instance modify --disk 2:add,size=3G,provider=emc,param5=value5

The above parameters will be exported to the ExtStorage provider's scripts as environment variables:

EXTP_PARAM1 = str(value1)
EXTP_PARAM2 = str(value2)
...

Inspired by gnt-os:

# gnt-storage diagnose
# gnt-storage info

man gnt-extstorage-interface
man gnt-storage
man gnt-instance {add,modify,migrate,failover}

Design doc: design-shared-storage.rst