Patching of virtual machines within sequential time windows

Patent metadata

Field	Value
Publication number	US-9696985-B1
Application number	US-201614989089-A
Country	US
Kind code	B1
Filing date	Jan 6, 2016
Priority date	Jan 6, 2016
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

A method and associated system for patching virtual machines in L redundancy groups in accordance with a patching schedule. The patching schedule is generated by scheduling, in W sequential time windows, P patches applicable to the virtual machines. Each redundancy group includes virtual machines and independently belongs to a respective software application x of X software applications, wherein P≧1, L≧1, R m ≧1, and X≧1. The L redundancy groups collectively comprise at least 2 virtual machines. The scheduling determines x wmk for T tuples (w, m, k) defined by (w=1, . . . , W) and (m=1, . . . , L) and (k=1, . . . , R m ), by maximizing an objective function subject to constraints. Determining x wmk includes setting x wmk =1 if virtual machine k in redundancy group m is to be patched in time window w or setting x wmk =0 otherwise.

First claim

What is claimed is:

1. A method for patching virtual machines in L redundancy groups in accordance with a patching schedule, said method comprising:
generating, by a processor of a computer system, the patching schedule applicable for patching the virtual machines in the L redundancy groups,
wherein said generating the patching schedule comprises scheduling, in W sequential time windows, P patches applicable to one or more virtual machines in the L redundancy groups, each redundancy group m (m=1, . . . , L) comprising R m virtual machines, each redundancy group m (m=1, . . . , L) independently belonging to a respective software application x of X software applications, wherein P≧1, L≧1, R m ≧1, and X≧1, wherein the L redundancy groups collectively comprise at least 2 virtual machines,
wherein said scheduling comprises determining, by the processor, x wmk for T tuples (w, m, k) defined by (w=1, . . . , W) and (m=1, . . . , L) and (k=1, . . . , R m ), by maximizing an objective function (F) subject to one or more constraints, wherein said determining x wmk comprises setting x wmk =1 if virtual machine k in redundancy group m is to be patched in time window w or setting x wmk =0 otherwise,
wherein the objective function F is a linear combination of N objective function components F n (n=1, . . . , N) expressed as F=Σ n=1 N α n F n subject to N≧1,
wherein α n (n=1, . . . , N) are specified weights satisfying α 1 >0 and α n >0 if n>1,
wherein F 1 =Σ x=1 X B x min w (Π m=1 L A(x, m, n wm )−Π m=1 L A(x, m, 0)),
wherein B x denotes a business criticality of software application x,
wherein n wm is a total number of virtual machines in redundancy group m assigned to time window w,
wherein n wm =Σ k=1 R m x wmk , and
wherein A(x, m, n wm ) denotes a residual availability of redundancy group m belonging to software application x when the n wm virtual machines in redundancy group m are not available in time window w; and
patching, by the processor, the virtual machines in the L redundancy groups according to the patching schedule.

2. The method of claim 1 , said method further comprising:
storing, by the processor, the determined x wmk , for said T tuples, in a data store of the computer system.

3. The method of claim 1 ,
wherein A(x, m, n wm )=(1−S xm Σ i=AR m R m -n wm ( i R m )f i (1−f) R m -i ),
wherein S xm =1 or 0 if redundancy group m belongs, or does not belong, to software application x, respectively,
wherein AR m is a minimum number of virtual machines to be available in redundancy group m for redundancy group m to be available, and
wherein f is a probability of failure of a virtual machine.

4. The method of claim 1 ,
wherein N≧2,
wherein F 2 =Σ w=1 W (1−I w ),
wherein I w =Σ m=1 L Σ k=1 R m x wmk λ wmk /Σ w=1 W Σ m=1 L Σ k=1 R m λ wmk , and
wherein λ wmk is a predicted rate of arrival of patching requests in time window w directed to virtual machine k in redundancy group m.

5. The method of claim 1 ,
wherein N≧2,
wherein

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Assignees

• IBM

Inventors

• Gupta Manish
• Puri Rajeev

Classifications

• G06F11/1433

  during software upgrading · CPC title

• G06F11/2048

  where the redundant components share neither address space nor persistent storage · CPC title

• G06F9/45533

  Hypervisors; Virtual machine monitors · CPC title

• G06F9/45558

  Hypervisor-specific management and integration aspects · CPC title

• G06F8/65 Primary

  Updates (security arrangements therefor G06F21/57) · CPC title