Services in the Virtualization Plane. Andrew Warfield Adjunct Professor, UBC Technical Director, Citrix Systems

Transcription

1 Services in the Virtualization Plane Andrew Warfield Adjunct Professor, UBC Technical Director, Citrix Systems

2 The Virtualization Plane Applications Applications OS Physical Machine

3 20ms 20ms in in the the Linux Linux Kernel Kernel 355, ,000 Branches Branches Syscalls, Syscalls, Interrupts, Interrupts, PFs PFs And And this this is is less less than than 10% 10% of of what what happened happened in in that that 20ms! 20ms! Geoff s call graph goes on this slide.

4 The Virtualization Plane Applications Applications OS Virtual Machine Monitor Physical Machine

5 The Virtualization Plane Appliance VM Appliance VM Appliance VM Appliance VM Appliance VM Appliance VM Virtual Machine Monitor Physical Machine Virtualization Machine Monitor Plane Physical Machine Virtual Machine Monitor Physical Machine Huge opportunity for innovation. OS agnostic and hardware agnostic. Build useful services that are co located, but isolated from VMs. Live migration was the first example.

6 Overview

7 Graduate Student: Brendan Cully REMUS: TRANSPARENT HIGH AVAILABILITY

8 Example 1: (Brendan Cully) Remus: Transparent High Availability As with process migration, HA is complicated and difficult to maintain. Database HA is generally based around a replicated log, and a recovery protocol based around detailed application semantics. HA is for the very rich and the very scared. Idea: Use simple mechanisms in the virtualization layer to provide universal HA.

9 Remus 3ms Mail Server VM PVM <17ms PVM Mail Server VM Xen Xen

10 Remus 3ms Mail Server VM Xen PVM <17ms checkpoint ok! PVM Mail Server VM Xen Internet

11 Remus Mail Server VM Internet Mail Server VM Remus demonstrates that PVM efficient and PVM complete state capture can provide hardware fault tolerant Xen Xen style whole system failover to unmodified applications. The simplicity of the approach is critical, because high availability and fault recovery code is notoriously difficult to get right.

12 Remus: Current Work Disaster Tolerant Computing. Extend HA/FT to work in the wide area. Deployment between UBC and TRU ~350km fiber connection. Exposing Remus to Applications. Apply paravirtualization to transparent HA. E.g. let a database know that some memory is unprotected

13 Remus: Summary Published at NSDI 2008 won Best Paper award. Some patches in xen unstable, remaining patches to appear over the next month or two. This summer, added support for HVM guests.

14 Graduate Student: Dutch Meyer PARALLAX: VIRTUAL STORAGE FOR VIRTUAL MACHINES

15 Parallax: Storage Virtualization for VMs VMs are fantastic, but turn out to be a bit clunky to work with. VM images are really big, and most storage systems don t really provide the operations you want to really innovate with VMs. Horizontal scale: create lots of images based on a gold master. Vertical Scale: Lots of snapshots of a single image. Thin provisioning is critical, as is low cost storage. Parallax is basically just page tables for disks!

16 Parallax: Storage Virtualization for VMs

17 Parallax Virtualizes block devices using address mapping trees. Very low overhead (2ms) snapshots. Equally low overhead image cloning. Space efficient. Many very interesting challenges. metadata data

18 Parallax Summary Parallax is used on a daily basis in our lab. Vertical integration of storage from array through to guest. Horizontal integration across hosts in a cluster. Storage is no longer a barrier for deploying new VMs. In the process of adding powerful new features: deduping, linearization, and CAS.

19 Graduate Students: Geoffrey Lefebvre and Brendan Cully TRALFAMADORE: ENHANCING AND UNDERSTANDING SYSTEMS

20 Tralfamadore: Motivation How much do we really know about what software is doing, especially when things go wrong? What if we had a detailed recording? What if the recording was interactive and could be queried and changed?

21 Tralfamadore Remus Checkpoints Parallax 1. Continuously log execution for long periods of time. Test/Dev Network Production Network

22 Tralfamadore Execution Index Indexing Servers Parallax Remus Checkpoints 2. Re execute slices of history to generate indexes. Test/Dev Network Production Network

23 Tralfamadore Execution Index Indexing Servers Parallax Remus Checkpoints Query Servers Find points in execution when /etc/passwd was modified network receive buffers were overloaded. the stack looked like this. control flow ran function b, shortly after running function a. 3. Queries to search, select, and interrogate history. Test/Dev Network Production Network

24 Tralfamadore Execution Index Indexing Servers Parallax Remus Checkpoints Use piles of existing tools: Emulators, Profilers, Binary Patching, Debuggers Query Servers Use repeated re execution to tackle non determinism. Re execution Servers 4. Re execute and analyze modified checkpoints. Test/Dev Network Production Network

25 Applications of Tralfamadore Fault injection / fuzzing of software close to real execution experience. Retrospectively attach a debugger to any node in this call graph. Test patches in the past!

26 Understanding Execution Prototype application of Tralfamadore performs dynamic analysis of trace data and maps it back on top of source code. Allows developers to understand how source is behaving in deployments. Very early work, but a few examples follow

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30 Tralfamadore Summary We hope to be able to do detailed, retrospective analysis of system behaviour. Current focus has been on understanding execution. Future work will involve performance and security analysis and assisting reproduction of system failures.

31 Overall Conclusions The virtualization plane presents a great opportunity to build low level extensions to software. I have shown three example services, and expect many more to follow. Interesting challenges exist in evolving virtualization to provide these services while maintaining isolation and cross platform benefits.

32 Thank You!