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This article mainly explains the "linux vdo verification analysis", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "linux vdo verification analysis" bar!

About VDO

VOD's technology comes from the acquired Permabit company, a company specializing in re-deletion technology, so there is no problem with technical reliability.

VDO is a kernel module that aims to reduce disk space consumption and replication bandwidth through re-deletion. VDO is based on the block device layer, that is, mapping mapper virtual devices on the basis of the original device, and then directly using it. The realization of the function is mainly based on the following technologies:

Exclusion of zero blocks:

In the initialization phase, the whole block of 0 is recorded by metadata, which can be explained by the example of mixing water and sand in the water cup. Filter paper (zero block exclusion) is used to filter out sand (non-zero space). Then there is the next stage of processing.

Deduplication:

In the second stage, the input data will determine whether it is redundant (before it is written). This part of the data will be judged (U niversal D eduplication S ervice) by the UDS kernel module, and the part that is judged to be duplicated will not be written, and then the metadata will be updated to point directly to the original stored data block.

Compression:

Once zeroing and re-deletion are completed, LZ4 compression will process each individual data block, and then the compressed data block will be stored on the media as a fixed-size 4KB block. Because a physical block can contain many compressed blocks, this can also speed up read performance.

The above technology seems to be easy to understand, but it is still quite difficult to make a product, and there is still a big gap between the technical idea and the actual output, otherwise redhat will not acquire the technology through acquisition instead of rewriting a set of its own.

How to get VDO

There are two main ways. One is to apply for the ISO of redhat 7.5 by applying for a beta version, which can be tested for one month.

Another way is to apply for a test version, and then use the source code to test on the ISO you are using. Testing on your own ISO in terms of adaptation can make a better comparison. As the distribution of the source code based on redhat will involve legal issues, you can apply for the test without too much explanation or rpm package.

References are as follows:

Https://ceph.com/planet/redhat-7-5beta-%E6%96%B0%E6%8E%A8%E5%87%BA%E7%9A%84vdo%E5%8A%9F%E8%83%BD/

CREATE DISKGROUP data NORMAL REDUNDANCY

FAILGROUP controller1 DISK

'/ devices/diska1'

'/ devices/diska2'

'/ devices/diska3'

'/ devices/diska4'

FAILGROUP controller2 DISK

'/ devices/diskb1'

'/ devices/diskb2'

'/ devices/diskb3'

'/ devices/diskb4'

ATTRIBUTE 'compatible.asm' =' 12.2', 'compatible.rdbms' =' 12.2'

'sector_size'='4096'

Set up asm diskgroup for testing. In the 11gR2 version, using sector_size to create a disk group for 4k disks was not successful.

Later, it cannot be created by using asmlib. Finally, the 12c version of asm instance is successfully created, which proves that 4k sector_size disks are supported in 12cR2 version.

After that, the product is used for vdo pressure test.

Thank you for your reading, the above is the content of "linux vdo verification analysis", after the study of this article, I believe you have a deeper understanding of the problem of linux vdo verification analysis, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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