Nir Soffer

Using checksums for verifying disk image download is very common, but how do you verify uploading a disk image to a virtual disk or verify that a backup is correct? The standard tools such as sha256sum cannot help since the disk image and the virtual disk may use different image formats. Even if the image formats match, standard tools are too slow to handle huge virtual disks which typically contain a small amount of data and a large amount of unallocated space.

In this talk we will learn about the blkhash algorithm for computing a fast checksum of sparse disk images, up to 3 orders of magnitude faster compared with standard algorithms, the libblkhash C library that you can use in your program, and the blksum command line tool for computing checksum of common disk image formats.

The blkhash project grew from the ovirt-imageio project, providing fast disk checksums since oVirt 4.4. The blkhash project adds support for multiple threads, uses the high performance libnbd library, and is implemented in C. The project is released under LGPL license so you can use it in your project or package it for your distribution.

How to run virtual machines in oVirt without copying their disks.

Have you ever wanted to run your virtual machine in oVirt without copying its hugh disks? Tired of checking the slow transfer progress? We did, and we have a good plan to avoid the wait!

In this talk we show how oVirt can start virtual machine without copying the disks, using external disk via NBD or other protocols supported by qemu. Once the virtual machine is running, copy the disks in the background to oVirt storage. This minimizes downtime to seconds instead of minutes, and can be used in many scenarios such as importing virtual machines from other systems (even from foreign systems via virt-v2v), previewing backups before restore, and provisioning a virtual machines.

Audience: Virtualization administrators or developers interested in oVirt architecture and would like a peek into future development.

Teaching oVirt to work with 4k storage.

How can we have compression and deduplication using VDO, the new Linux compression layer? How can we use the latest and greatest disks drives? We need to support disks with 4k block size.

oVirt is your best friend when you need to manage your virtualized data center, but when it was created 10 years ago, support for 4k storage was not considered. Can you teach an old dog new tricks? Sure you can!

In this talk we will share what we learned implementing 4k storage support in oVirt. We will present the challenges teaching old and stubborn code base to work with disks using 4k storage, and how we addressed them; introducing storage format v5, moving from sectors to bytes, detection of block size on file storage, improving testing in storage area, adding new 4k APis to sanlock and improving qemu block size detection.

Audience: oVirt administrator interested in utilizing the latest and greatest features and hardware. Developers looking for new ways to deal with old code.