From: Hamish Moffatt <hamish-btrfs@moffatt.email>
To: Nikolay Borisov <nborisov@suse.com>,
Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: new database files not compressed
Date: Mon, 31 Aug 2020 20:40:18 +1000 [thread overview]
Message-ID: <4b5ff37f-2659-0757-cdc4-e3704ba9768b@moffatt.email> (raw)
In-Reply-To: <1ba6d793-30c5-39fc-3b6f-46fee70e5dd8@suse.com>
On 31/8/20 7:25 pm, Nikolay Borisov wrote:
>
> Doing the following test :
>
> root@ubuntu18:~# mount -O compress-force=zstd /dev/vdc /media/scratch/
> root@ubuntu18:~# rm -rf /media/scratch/zero
> root@ubuntu18:~# dd if=/dev/zero of=/media/scratch/zero bs=16k count=1024
> sync
> btrfs inspect-internal dump-tree -t5 /dev/vdc
>
> results in:
>
>
> item 6 key (259 EXTENT_DATA 0) itemoff 15816 itemsize 53
> generation 12 type 1 (regular)
> extent data disk byte 315621376 nr 4096
> extent data offset 0 nr 131072 ram 131072
> extent compression 3 (zstd)
> item 7 key (259 EXTENT_DATA 131072) itemoff 15763 itemsize 53
> generation 12 type 1 (regular)
> extent data disk byte 315625472 nr 4096
> extent data offset 0 nr 131072 ram 131072
> extent compression 3 (zstd)
> item 8 key (259 EXTENT_DATA 262144) itemoff 15710 itemsize 53
> generation 12 type 1 (regular)
> extent data disk byte 315629568 nr 4096
> extent data offset 0 nr 131072 ram 131072
> extent compression 3 (zstd)
>
>
>
> I.e a bunch of 128k extents, which in fact take only 4k on disk each.
>
> Whereas if I write the same file but without the compress-force mount
> option I get:
>
> item 138 key (260 EXTENT_DATA 0) itemoff 8787 itemsize 53
> generation 14 type 1 (regular)
> extent data disk byte 298844160 nr 16777216
> extent data offset 0 nr 16777216 ram 16777216
> extent compression 0 (none)
>
>
> I.e a single extent, 16m in size. So instead of using this compsize
> utility or whatever it is can you dump the state of the filesystem as
> per the btrfs inspect-internal command shown above?
I used compsize as recommended by the wiki page:
https://btrfs.wiki.kernel.org/index.php/Compression#How_can_I_determine_compressed_size_of_a_file.3F
I created a new file system, ran dd bs=32k count=1024, then the dump
shows me items all the way up to item 161. https://pastebin.com/0MPPdqqM
item 160 key (258 EXTENT_DATA 33292288) itemoff 7750 itemsize 53
generation 7 type 1 (regular)
extent data disk byte 14671872 nr 4096
extent data offset 0 nr 131072 ram 131072
extent compression 3 (zstd)
item 161 key (258 EXTENT_DATA 33423360) itemoff 7697 itemsize 53
generation 7 type 1 (regular)
extent data disk byte 14675968 nr 4096
extent data offset 0 nr 131072 ram 131072
extent compression 3 (zstd)
total bytes 32196018176
bytes used 1245184
uuid 53eaed91-1060-445b-bf7c-5efe9917adbc
From mount: /dev/sdb on /mnt/test type btrfs
(rw,relatime,compress-force=zstd:3,space_cache,subvolid=5,subvol=/)
Hamish
next prev parent reply other threads:[~2020-08-31 10:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-30 9:35 new database files not compressed Hamish Moffatt
2020-08-31 2:20 ` Eric Wong
2020-08-31 2:44 ` Hamish Moffatt
2020-08-31 3:15 ` A L
2020-08-31 3:47 ` Zygo Blaxell
2020-08-31 8:53 ` Hamish Moffatt
2020-08-31 9:25 ` Nikolay Borisov
2020-08-31 10:40 ` Hamish Moffatt [this message]
2020-08-31 10:47 ` Nikolay Borisov
2020-08-31 12:56 ` Hamish Moffatt
2020-08-31 11:15 ` Roman Mamedov
2020-08-31 12:54 ` Hamish Moffatt
2020-08-31 12:57 ` Nikolay Borisov
2020-08-31 23:50 ` Hamish Moffatt
2020-09-01 5:15 ` Nikolay Borisov
2020-09-01 8:55 ` Hamish Moffatt
2020-09-02 0:32 ` Hamish Moffatt
2020-09-02 5:57 ` Nikolay Borisov
2020-09-02 6:05 ` Hamish Moffatt
2020-09-02 6:10 ` Nikolay Borisov
2020-09-02 9:57 ` A L
2020-09-02 10:09 ` Nikolay Borisov
2020-09-03 15:04 ` A L
2020-09-02 16:16 ` Zygo Blaxell
2020-09-03 12:53 ` Hamish Moffatt
2020-09-03 19:44 ` Zygo Blaxell
2020-09-04 8:07 ` Hamish Moffatt
2020-09-05 4:07 ` Zygo Blaxell
2020-09-03 15:03 ` A L
2020-09-03 21:52 ` Zygo Blaxell
2020-09-01 1:43 ` Chris Murphy
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