Re: Why btrfs inline small file by default?

[ching <lsching17@gmail.com>]

On 10/31/2012 06:19 AM, Hugo Mills wrote:
> On Tue, Oct 30, 2012 at 10:14:12PM +0000, Hugo Mills wrote:
>> On Wed, Oct 31, 2012 at 05:40:25AM +0800, ching wrote:
>>> On 10/30/2012 08:17 PM, cwillu wrote:
>>>>>> If there is a lot of small files, then the size of metadata will be
>>>>>> undesirable due to deduplication
>>>>> Yes, that is a fact, but if that really matters depends on the use-case
>>>>> (e.g., the small files to large files ratio, ...). But as btrfs is designed
>>>>> explicitly as a general purpose file system, you usually want the good
>>>>> performance instead of the better disk-usage (especially as disk space isn't
>>>>> expensive anymore).
>>>> As I understand it, in basically all cases the total storage used by
>>>> inlining will be _smaller_, as the allocation doesn't need to be
>>>> aligned to the sector size.
>>>>
>>> if i have 10G small files in total, then it will consume 20G by default.
>>    If those small files are each 128 bytes in size, then you have
>> approximately 80 million of them, and they'd take up 80 million pages,
>> or 320 GiB of total disk space.
>    Sorry, to make that clear -- I meant if they were stored in Data.
> If they're inlined in metadata, then they'll take approximately 20 GiB
> as you claim, which is a lot less than the 320 GiB they'd be if
> they're not.
>
>    Hugo.
>


is it the same for:
1. 3k per file with leaf size=4K
2. 60k per file with leaf size=64k