Re: Btrfs Heatmap - v2 - block group internals!

[Hans van Kranenburg <hans.van.kranenburg@mendix.com>]

Hey,

On 11/17/2016 02:27 AM, Qu Wenruo wrote:
> 
> At 11/17/2016 04:30 AM, Hans van Kranenburg wrote:
>> In the last two days I've added the --blockgroup option to btrfs heatmap
>> to let it create pictures of block group internals.
>>
>> Examples and more instructions are to be found in the README at:
>> https://github.com/knorrie/btrfs-heatmap/blob/master/README.md
>>
>> To use the new functionality it needs a fairly recent python-btrfs for
>> the 'skinny' METADATA_ITEM_KEY to be present. Latest python-btrfs
>> release is v0.3, created yesterday.
>>
> Wow, really cool!

Thanks!

> I always dream about a visualizing tool to represent the chunk and
> extent level of btrfs.
> 
> This should really save me from reading the boring dec numbers from
> btrfs-debug-tree.
> 
> Although IMHO the full fs output is mixing extent and chunk level
> together, which makes it a little hard to represent multi-device case,
> it's still an awesome tool!

The picture of a full filesystem just appends all devices together into
one big space, and then walks the dev_extent tree and associated
chunk/blockgroup items for the %used/greyscale value.

I don't see what displaying a blockgroup-level aggregate usage number
has to do with multi-device, except that the same %usage will appear
another time when using RAID1*.

When generating a picture of a file system with multiple devices,
boundaries between the separate devices are not visible now.

If someone has a brilliant idea about how to do this without throwing
out actual usage data...

-- 
Hans van Kranenburg