Dell EMC PowerVault ME4 Series. ADAPT Linear pools and disk groups. Quick rebuild.

Many thanks for the prompt reply. 

From your answer I've made the following conclusions:
1) Quick rebuild and ADAPT are completely different and not interconnected technologies.

2)  ADAPT does work with linear disk groups.

Now the question is, will ADAPT virtual disk groups + "Quick rebuild" work faster compared to ADAPT linear disk groups rebuild?

It is a different technologyes. ADAPT significantly reduce rebuild time via parallel architecture.

When more than 1 drive member of the array has been failed, some stripes will have 1 and others 2 chunks lost, depending on how they fall within the layout of the array. These stripes with 2 members lost are more at risk than ones with one as any further loss of data within that stripe can no longer be corrected or protected. Therefore, a priority to stripes that have 2 chunks lost is given in the rebuild process. This means that there are 2 critical measurements of rebuild, one to get back redundancy, the other to complete the rebuild and get back to optimal state. 

ADAPT only needs to do this process for the stripes that are impacted by the loss of the drives. This
leads to less data requiring rebuild. Further as the array gets wider the contribution to that amount of data
reduces per member and thus as the arrays get wider the improvement in rebuild time increases.

You can check this documentation: https://dell.to/3rjkQef

Regards.

Yes, you are correct: An ADAPT disk group can be created in Linear or Virtual modes. In Linear the space is allocated across all members of the array. In the virtual case, it is allocated as needed on a page by page basis as new space within the Volume is created. When virtual mode is selected other features are enabled like, for example, Tiering.

But both ADAPT methods handle spare drives in a different way to traditional RAID. A reserve of spare drive capacity is taken from the available space that is constructed. This allows rebuilds to be conducted within the array. The advantages of this approach are considerable as it allows faster rebuilds because all members of the disk group array are used in the rebuild process. 

In conclusion, using any ADAPT (linear or virtual) you will be having a very fast rebuild.

If there is no difference in rebuilding speed between an ADAPT linear disk group and an ADAPT virtual disk group, I cannot understand why you emphasize the quick rebuild feature as a separate feature that is only available for the virtual disk group. There must be some advantages.

Sorry, I think I did not explain myself properly: Quick rebuild is only for virtual storage. For virtual storage, reconstruction of all disk groups uses a quick-rebuild feature.

Quick rebuild is a method for reconstructing virtual disk groups that reduces the time that user data is less
than fully fault-tolerant after a disk failure in a disk group. Taking advantage of virtual storage knowledge of
where user data is written, quick rebuild only rebuilds the data stripes that contain user data.

Typically, storage is only partially allocated to volumes, so the quick-rebuild process completes significantly
faster than a standard RAID rebuild. Data stripes that have not been allocated to user data are scrubbed in
the background, using a lightweight process that allows future data allocations to be more efficient.

After a quick rebuild, a scrub starts on the disk group within a few minutes after the quick rebuild completes.
Quick rebuild is only usable in ADAPT not in traditional RAID

Regards.

Could you please elaborate how much faster (at least very roughly)?

Thank you in advance.

I have read the instructions/documentations (I even wrote/made links to the descriptions of the features in my posts), my question is still unanswered.

The question is, will ADAPT virtual disk groups + "Quick rebuild" work faster compared to ADAPT linear disk groups rebuild?

I am afraid currently there are not available white papers with benchmarks over this that could show you the differences.

I suggest you to contact directly to the Dell Commercial department where they will be able to provide you with such information: https://dell.to/3fliSYG

Regards.