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Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file




On Mon, 8 Apr 2019 at 22:38, <rhkramer@xxxxxxxxx> wrote:
> On Sunday, April 07, 2019 04:22:41 PM Reco wrote:
> > On Sun, Apr 07, 2019 at 10:10:58PM +0200, Carles Pina i Estany wrote:
>
> > > In my SSDs I have:
> > > /sys/fs/ext4/dm-0/lifetime_write_kbytes
> > >
> > > I'm not sure if this is specific for SSD?
> >
> > No, it's not. It's filesystem-specific though.
> > Meaning - you have to use ext4 to see this attribute, but the device
> > where the ext4 filesystem resides does not matter.
>
> Well, to clarify, if you have multiple ext4  filesystems, does that represent
> the sum of lifetime_write_kbytes of all of those filesystems?

No, the device is in the path, after the filesystem type.
The device above is dm-0. Here's an example from this machine,
for device sda10:
$ cat /sys/fs/ext4/sda10/lifetime_write_kbytes
8589077

A quick search found this (it's not recent) which might give you
some things to try:
https://serverfault.com/questions/238033/measuring-total-bytes-written-under-linux