Presented in Design track of OpenStack Summit, 2012 Fall San Diego. http://openstacksummitfall2012.sched.org/event/b3fca04cd2762fe64bbd64df9c198f36

1. Island: Local Storage plugin for Cinder
在这里写上你的标题
Presented at OpenStack Summit, San Diego
副标题文字副标题文字
Hui Cheng/RongZhe Zhu
freedomhui@gmail.com | zrzhit@gmail.com
作者名字 / 日
2012-09-22
期

2. Content
1. Why
00 写上你的文字你的文字
2. Design
01
3. Snapshot
02
4. Discussions
03
04
05
https://blueprints.launchpad.net/cinder/+spec/local-storage-volume

3. Why
AWS EBS
写上你的文字你的文字
Island
00
Network bottleneck High durability
01
Re-mirroring storm =
Incremental snapshot
02 The high performance of
Low performance Snapshots store in S3
12 disks RAID10
03
Incremental snapshot
Our Environment
04
Snapshots store in swift
05 写上你的文字你的文字
Every x86 server have
1000Mb Network
12 disks

4. Design – Island in Cinder KEY
REST
Users
AMQP
Nova API Volume API SQL
POSIX
=
Nova cinder Cinder
RPC RPC DB
Nova
DB
Swift API
Compute Volume Snapshot in Swift
Manager Manager
Host
Island
KVM
Swift Storage
Guest
images
Island Design Idea= Local Storage + QCOW2 Image + Dependent Snapshot + Swift

5. Design – Incremental Snapshot in Swift
00
VM VM VM
Snapshots are saved incrementally.
Each subsequent snapshot will only
01 save modified data block to swift. A
02
image image image
=
Host table of contents points to the latest
versions of each data block. Each
data block have a reference counter.
03
04
05 snap snap snap
1 2 3
Swift
1 2 3 4 1 2 2 3

6. create_volume
delete_volume
Design – Island Architecture create_volume_from_snapshot
create_snapshot
delete_snapshot
create_vdisk 写上你的文字你的文字 attach_volume
00
delete_vdisk detach_volume
create_snapshot IslandDriver ……
01
delete_snapshot
read_vdisk
02
write_vdisk
= get_snapshot
put_snapshot
get_update_blocks Snapshot
03
read_vdisk_meta
delete_snapshot
get_object
04 put_object
delete_object
05 set_object_meta
Vdisk ObjectStorage
get_object_meta
QCOW2 VDMK Swift NFS Glusterfs

7. Design - Process
00
Create volume
Do nothing
01
Create volume from snapshot
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Do nothing
=
03
Delete volume
Do nothing
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Delete snapshot
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Island delete snapshot in swift

8. Design - Process Create the
image of the
volume
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Attach volume
00
01 volume
old Check the new volume form snapshot
02 =
volume
03
Download the last Download
snapshot and snapshot and
04wirte it to the new volume wirte it to the
image image
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Update
volume[‘host’]

9. Design - Process
Create snapshot
00 Detach volume
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Create a new snapshot DB item, set
Create snapshot in image snapshot[‘volume_id’] as the volume
02
03
Upload incremental Create snapshot in image
snapshot to swift
04
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Delete old snapshot in Upload incremental snapshot to swfit
image
Delete the image of the volume

10. Snapshot – How to Create/Read Snapshot in Image
Create internal snapshot in image
Because there写上你的文字你的文字 command to create internal snapshot
is not a qemu monitor
00
in image when the image was attached. So, we add a new qemu monitor
command to create point-in-time snapshot in image.
01
Accessing QCOW2 image in python
02 =
QCOW2 image format use 2-level Lookup Table
http://people.gnome.org/~markmc/qcow-image-format.html
03
We implement qcow2 python library to read/write qcow2 image data and
metadata.
04
05

11. Snapshot – How to Implement Incremental Snapshot
00 写上你的文字你的文字 Compare current snapshot pointer
table and previous snapshot pointer
01 table in image
We need to find out updated data blocks
between two02snapshots. =
Find updated data blocks
03
04
Upload updated data blocks to
05 objectstorage
Future: modify qcow2 driver in qemu, mark
updated data blocks in pointer table of Upload snapshot pointer table to
snapshot in image. objectstorage

12. Discussions
The 00 写上你的文字你的文字
storage capacity of a x86 server is limit, but if many
instances in a server and many volume are attached to
01
these instances, it will be a issue.
The 02
=
attach volume action is slower than other plugin.
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Optimization?
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Make Island as a independent system?
05