[GTALUG] File larger than partition? (Docker-related)

[William Park]

You can also try 'du -h'.
-- 
William Park <opengeometry at yahoo.ca>

On Mon, Nov 20, 2017 at 11:31:01PM +0000, Giles Orr via talk wrote:
> On 20 November 2017 at 18:58, Lennart Sorensen <lsorense at csclub.uwaterloo.ca
> > wrote:
> > ~> dd if=/dev/zero bs=1M count=1 seek=1000 of=testfile
> > 1+0 records in
> > 1+0 records out
> > 1048576 bytes (1.0 MB) copied, 0.00203937 s, 514 MB/s
> > ~> ls -lhs testfile
> > 1.0M -rw-r--r-- 1 lsorensen users 1001M Nov 20 13:56 testfile
> >
> > So 1MB allocated out of 1001MB file size.  The first 1000MB are a 'hole'
> > in the file that isn't allocated yet.
> >
> > The -s option to ls makes it show the allocated space in the first column.
> 
> 
> Wow.  I did not know that, thank you.  And I see there's a specific switch
> to rsync for better handling of sparse files.
> 
> But ... then what exactly does straight-up 'ls' (without the '-s') report?
> The man page says '-s' "print[s] the allocated size of each file, in
> blocks."  I was under the mistaken impression (for 23 years now) that that
> was more or less what 'ls' was already doing.
> 
> Here are some answers: https://en.wikipedia.org/wiki/Sparse_file ...  I get
> the utility of the idea, but it seems to come with some fairly significant
> hazards.
> 
> 'ls' can be made to indicate directories (with '/') and links (with '@')
> and a couple other things with '-F'/'--classify': sparse files would seem
> to be staggeringly misleading and thus a good target for this kind of
> marking as well ...  Is that possible?
> 
> Where else am I likely to run into sparse files?  Sounds like mostly things
> that create file systems, like VirtualBox and friends, Docker (obviously)
> .. anywhere else?
> 
> Sorry to ask so many questions, but 'ls' seems like one of the most basic
> commands of Linux and I thought I knew what it did: I'm suddenly feeling
> like a newbie again and would like to get a handle on this ...
> 
> -- 
> Giles
> https://www.gilesorr.com/
> gilesorr at gmail.com

> ---
> Talk Mailing List
> talk at gtalug.org
> https://gtalug.org/mailman/listinfo/talk