Re: [PLUG] Reclaiming inodes

[bergman@merctech.com]

In the message dated: Thu, 28 Sep 2017 15:13:37 -0400,
The pithy ruminations from Rich Freeman on 
<Re: [PLUG] Reclaiming inodes> were:
=> On Thu, Sep 28, 2017 at 3:07 PM, Steve Litt <slitt@troubleshooters.com> wrote:
=> >
=> > OK, I believe you. So let me rephrase:
=> 
=> Sorry if that came across as confrontational.
=> 
=> >
=> > If you have an SSD, frequently run fstrim on all your SSD partitions to
=> > reclaim deleted space. Doing so has many benefits.

Um, depends on your definition of "frequently". According to the fstrim man page:

       Running fstrim frequently, or even using mount -o discard, might
       negatively affect the lifetime of poor-quality SSD devices.
       For most desktop and server systems a  sufficient  trimming
       frequency is once a week.  Note that not all devices support a
       queued trim, so each trim command incurs a performance penalty
       on whatever else might be trying to use the disk at the time.

	From: util-linux-2.28.2-2.fc25.x86_64

=> >
=> 
=> Completely agree.  I just might note that on some drives (I think that
=> includes the popular Evo series) the kernel makes fstrim a no-op, due

Yep.

=> to vendor bugs.
=> 
=> fstrim has a lot of benefits (which I'm sure google can lead anybody
=> to).  It just doesn't have anything to do with reclaiming inodes.  As
=> far as I'm aware inodes go away as soon as you unlink anything in all

Nope.

[pseudo-code]
	int fd;
 	fd = open(filename, O_RDWR);
	unlink(filename);
[/pseudo-code]

The inode will exist and the file will continue to use space (sometimes
filling a filesystem or quota) until close(filename) is called.

The file will not be visible (except to tools like lsof).

Very, very common technique for creating "self-cleaning" temp files. 

=> non-snapshotting filesystems, and when the last snapshot is deleted
=> otherwise.
=> 
=> -- 
=> Rich
=> 

-- 
Mark 
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