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Coordinated Cloud Image Creation

IP.com Disclosure Number: IPCOM000250336D
Publication Date: 2017-Jun-29
Document File: 2 page(s) / 27K

Publishing Venue

The IP.com Prior Art Database

Abstract

By employing a naming convention for Image LUs, and a system of markers

indicating uploads in progress, a given thread can determine if an Image

LU for a given source image is already present on the SSP, or being

created by another thread, even if that thread is on a different host.

However, we also need to account for the fact that an Image LU can't be

used until it has been fully populated.

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Coordinated Cloud Image Creation

By employing a naming convention for Image LUs and a system of markers indicating uploads

in progress, a given thread can determine if an Image LU for a given source image is already

present on the SSP or being created by another thread, even if that thread is on a different host.

However, one also needs to account for the fact that an Image LU can't be used until it has been

fully populated.

TERMINOLOGY

Shared Storage Pool (SSP): For the purposes of this document, the term SSP will be used to

represent any storage technology with the following characteristics:

- The storage medium itself is accessible from multiple servers, which may not otherwise have

any mechanisms for communicating with one another.

- The technology supports thin clones.

The existing embodiment of this invention uses PowerVM Shared Storage Pools, wherein a

group of collaborating Virtual I/O Servers (VIOSes) shares storage, typically hosted from a

Storage Area Network (SAN), and is able to carve out LUs that can be accessed from/through

any of the VIOSes.

Logical Unit (LU): A virtual disk created by the SSP on the storage medium, which can be

presented to a Virtual Machine (VM) in such a way that it appears as a physical hdisk to the VM.

This document uses the term "LU" to refer to any virtual disk hosted by the storage technology.

Image LU: A particular type of Logical Unit used to store a disk image. An Image LU typically

consumes an amount of space on the storage medium equivalent to the size of the image it is

storing. The Image LU is read-only once it has been created and populated.

Thin Clone LU (Thin Clone): A particular type of Logical Unit used as a (bootable and/or data)

read-write disk by a VM. A Thin Clone is backed by an Image LU in such a way that data from

the Image LU need not exist in the Thin Clone itself unless it is modified. This may be

accomplished by means of Copy-On-Write (COW) technology. A Thin Clone typically

consumes only a tiny fraction of the back-end storage space of its backing Image LU, though it

still appears to the VM as though it has the full size of the Image LU.

MD5 hash: A 128-bit checksum of a data blob, often represented as a 32-character hexadecimal

string. The MD5 algorithm is such that it always produces the same result for the same data

blob; and the probability of two different data blobs having the same MD5 hash is infinitesimal.

Image LUs are named according to a convention such that the name includes the MD5 hash of

the image, as a 32-character hexadecimal string. (Note that any similarly robust hashing

algorithm could be used.) Thread B first lists the Image LUs on the SSP, and if it finds one with

that MD5 hash, it uses it (creates a Thin Clone against it). If no such Image LU exists, thread B

attempts to create and populate it,subject to the algorithm further described below.

When an Image LU is first created, it is empty; it needs to be populated with the data from the

source image. This...