Original Message
Subject: Re: Why is the actual disk usage of btrfs considered unknowable?
From: ashf...@whisperpc.com
To: kreij...@inwind.it
Date: 2014å¹´12æ08æ¥ 08:12
Goffredo,
So in case you have a raid1 filesystem on two disks; each disk has
300GB
free; which
On Sun, Dec 7, 2014 at 1:32 PM, ashf...@whisperpc.com wrote:
I disagree. My experiences with other file-systems, including ZFS, show
that the most common solution is to just deliver to the user the actual
amount of unused disk space. Anything else changes this known value into
a guess or
On 12/08/2014 01:12 AM, ashf...@whisperpc.com wrote:
Goffredo,
So in case you have a raid1 filesystem on two disks; each disk has 300GB
free; which is the free space that you expected: 300GB or 600GB and why ?
You should see 300GB free. That's what you'll see with RAID-1 with a
hardware
Hi,
Am Sonntag, 7. Dezember 2014, 21:32:01 schrieb Robert White:
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
Well what would be possible I bet would be a kind of system call like
this:
I need to write 5 GB of data in 100 of files to /opt/mynewshinysoftware,
can I do it *and*
On 2014-12-08 09:47, Martin Steigerwald wrote:
Hi,
Am Sonntag, 7. Dezember 2014, 21:32:01 schrieb Robert White:
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
Well what would be possible I bet would be a kind of system call like
this:
I need to write 5 GB of data in 100 of files to
Am Montag, 8. Dezember 2014, 09:57:50 schrieb Austin S Hemmelgarn:
On 2014-12-08 09:47, Martin Steigerwald wrote:
Hi,
Am Sonntag, 7. Dezember 2014, 21:32:01 schrieb Robert White:
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
Well what would be possible I bet would be a kind of
On Mon, Dec 08, 2014 at 03:47:23PM +0100, Martin Steigerwald wrote:
Am Sonntag, 7. Dezember 2014, 21:32:01 schrieb Robert White:
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
Almost full filesystems are their own reward.
So you basically say that BTRFS with compression does not meet
Hi Shriramana!
Am Sonntag, 7. Dezember 2014, 20:45:59 schrieb Shriramana Sharma:
IIUC:
1) btrfs fi df already shows the alloc-ed space and the space used out of
that.
2) Despite snapshots, CoW and compression, the tree knows how many
extents of data and metadata there are, and how many
On Sun, Dec 7, 2014 at 9:03 PM, Martin Steigerwald mar...@lichtvoll.de wrote:
I never read that the actual disk usage is unknown. But I read that the actual
what is free is unknown. And there are several reasons for that:
That is totally understood. But I guess when your alloc space is
nearing
Am Sonntag, 7. Dezember 2014, 16:33:37 schrieb Martin Steigerwald:
What might be possible but still has the limitation of the fourth point
above, would be a query: How much free space do you have *right* know, on
this directory path, if I write with standard settings.
But the only guarantee
Martin,
I read that the actual
what is free is unknown. And there are several reasons for that:
1) On a compressed filesystem you cannot know, but only estimate the
compression ratio for future data.
It is NOT the job of BTRFS, or ANY file-system, to try to prodict the
future. The future
On Sun, Dec 07, 2014 at 10:20:27AM -0800, ashf...@whisperpc.com wrote:
[snip]
3) From what I gathered it is planned to allow different raid /
redundancy levels for different subvolumes. BTRFS can´t know
beforehand where applications request to save future data, i.e.
in which subvolume.
Am Sonntag, 7. Dezember 2014, 10:20:27 schrieb ashf...@whisperpc.com:
Martin,
I read that the actual
what is free is unknown. And there are several reasons for that:
1) On a compressed filesystem you cannot know, but only estimate the
compression ratio for future data.
It is NOT
Am Sonntag, 7. Dezember 2014, 18:34:44 schrieb Hugo Mills:
On Sun, Dec 07, 2014 at 10:20:27AM -0800, ashf...@whisperpc.com wrote:
[snip]
3) From what I gathered it is planned to allow different raid /
redundancy levels for different subvolumes. BTRFS can´t know
beforehand where
On 12/07/2014 04:33 PM, Martin Steigerwald wrote:
Hi Shriramana!
Am Sonntag, 7. Dezember 2014, 20:45:59 schrieb Shriramana Sharma:
IIUC:
1) btrfs fi df already shows the alloc-ed space and the space
used out of that.
2) Despite snapshots, CoW and compression, the tree knows how
many
On Sun, Dec 07, 2014 at 10:20:27AM -0800, ashf...@whisperpc.com wrote:
[snip]
3) From what I gathered it is planned to allow different raid /
redundancy levels for different subvolumes. BTRFS can´t know
beforehand where applications request to save future data, i.e.
in which subvolume.
Am Sonntag, 7. Dezember 2014, 10:20:27 schrieb ashf...@whisperpc.com:
Martin,
I read that the actual
what is free is unknown. And there are several reasons for that:
1) On a compressed filesystem you cannot know, but only estimate the
compression ratio for future data.
It is NOT the
3.1) even in the case of a single disk filesystem, data and metadata
have different profiles: the data chunk doesn't have any redundancy,
so 64kb of data consume 64kb of disk space. The metadata chunks
usually are stored as DUP, so 64kb of metadata consume 128kb on disk.
Moreover you have to
Goffredo,
So in case you have a raid1 filesystem on two disks; each disk has 300GB
free; which is the free space that you expected: 300GB or 600GB and why ?
You should see 300GB free. That's what you'll see with RAID-1 with a
hardware RAID controller, and with MD RAID. Why would you expect
Original Message
Subject: Re: Why is the actual disk usage of btrfs considered unknowable?
From: ashf...@whisperpc.com
To: kreij...@inwind.it
Date: 2014年12月08日 08:12
Goffredo,
So in case you have a raid1 filesystem on two disks; each disk has 300GB
free; which is the free
On 12/07/2014 07:15 AM, Shriramana Sharma wrote:
IIUC:
1) btrfs fi df already shows the alloc-ed space and the space used out of that.
2) Despite snapshots, CoW and compression, the tree knows how many
extents of data and metadata there are, and how many bytes on disk
these occcupy, no matter
On Sun, Dec 7, 2014 at 11:34 AM, Hugo Mills h...@carfax.org.uk wrote:
*Any* value shown here is going to be inaccurate, and whatever way
round we show it, someone will complain.
Yeah I'd suggest that for regular df command, when multiple device
volumes exist, they're shown with ?? for Avail
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
Well what would be possible I bet would be a kind of system call like this:
I need to write 5 GB of data in 100 of files to /opt/mynewshinysoftware, can I
do it *and* give me a guarentee I can.
So like a more flexible fallocate approach as
Martin,
Excellent analysis.
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
So while the core problem isn't insoluble, in real life it is _not_
_worth_ _solving_.
I agree. There is inadequate return on the investment. In addition, the
number of corner cases increases dramatically,
On Sun, Dec 07, 2014 at 08:45:59PM +0530, Shriramana Sharma wrote:
IIUC:
1) btrfs fi df already shows the alloc-ed space and the space used out of
that.
2) Despite snapshots, CoW and compression, the tree knows how many
extents of data and metadata there are, and how many bytes on disk
On 12/07/2014 10:20 PM, ashf...@whisperpc.com wrote:
Martin,
Excellent analysis.
On 12/07/2014 07:40 AM, Martin Steigerwald wrote:
So while the core problem isn't insoluble, in real life it is _not_
_worth_ _solving_.
Your email quoting things is messed up... I wrote that analysis... 8-)
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