Re: [gentoo-user] External hard drive and idle activity

[Rich Freeman]

On Mon, Jan 6, 2020 at 8:25 AM Mick <michaelkintzios@×××××.com> wrote:
>
> If they are used as normal PC drives for regular writing
> of data, or with back up commands which use rsync, cp, etc. then the disk will
> fail much sooner than expected because of repeated multiple areas being
> deleted, before each smaller write.  I recall reading about how short the life
> of SMR drives was shown to be when used in NAS devices - check google or
> youtube if you're interested in the specifics.

Can you give a link - I'm not finding anything, and I'm a bit dubious
of this claim, because they still are just hard drives.  These aren't
SSDs and hard drives should not have any kind of erasure limit.

Now, an SMR used for random writes is going to be a REALLY busy drive,
so I could see the drive being subject to a lot more wear and tear.
I'm just not aware of any kind of serious study.  And of course any
particular model of hard drive can have reliability issues (just look
up the various reliability studies).

> Personally, I would only use such a drive for 'keepers'.  Say, films I intend
> to write once and watch many times, ripped music albums, family photos, etc.
> For OS files and other temporary backups I would use a normal PC drive.

Certainly I would never use an SMR for an OS or /home.  Backups should
be fine, as long as you're using a sequential backup file format.
tar/duplicity should be fine.  Dar is probably fine but I'd need to
check (I think it just writes the index to the end, so the seeking
issues are on reading and not writing).  Even zip/etc is going to be
fine.  What is going to be a problem is anything that just replicates
the original data as all the separate files/directories that exist on
the original drive, like rsync/rsnapshot/etc.  Those formats are of
course attractive because the backup is just a replica of the
original, but they involve random writes.  Most formats that just
create a bunch of files named archive-001.foo that need a special
command to restore are going to be fine.

I personally haven't encountered a need to consider an SMR drive as
you can shuck those 12TB Easystore drives for something like $180 on
sale, at least in the US.  Those are just standard drives (often with
red firmware).  I couldn't even use them for my multimedia as I'm
storing that stuff on lizardfs right now and that breaks everything
into chunks.  Granted, I don't rewrite it often but unless zfs is
SMR-aware it is still going to be writing lots of modest-sized files
as the original files get chunked up and distributed across the nodes.
On the disk lizardfs data just looks like a browser cache, with
everything in numbered files about 60MB in size in my case.  The files
also appear to turn over a bit during rebalancing.

-- 
Rich