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Re: smartd

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On Du, 23 ian 22, 19:09:48, Linux-Fan wrote:
> peter@easthope.ca writes:
> > 
> > I knew nothing of RAID.  Therefore read here.
> > https://en.wikipedia.org/wiki/RAID
> > 
> > Reliability is more valuable to me than speed.  RAID 0 won't help.
> > For reliability I need a mirrored 2nd drive in the host; RAID 1 or
> > higher.
> > 
> > Google of "site:wiki.debian.org raid" returned ten pages, each quite
> > specialized and jargonified.  A few tips to establish mirroring can
> > help.
> 
> Here, it returns a few results, too. I think the most straight-forward is
> this one:
> 
> https://wiki.debian.org/SoftwareRAID
> 
> For most purposes, I recommend RAID1. If you have four HDDs of identical
> size, RAID10 might be tempting, too, but I'd still consider and possibly
> prefer just creating two independent RAID1 arrays.
> 
> If you want to configure it from the installer, these step-by-step
> instructions show all the relevant installer screens:
> 
> https://sleeplessbeastie.eu/2013/10/04/how-to-configure-software-raid1-during-installation-process/
> 
> Also, keep in mind that establishing the mirroring is not all you need to
> do. To really profit from the enhanced reliability, you need to play through
> the recovery scenario, too. I recommend doing this in a VM unless you have
> some dedicated machine with at least two HDDs to play with.

Another thing to consider is that Linux Software RAID (also known as 
"md" or "mdadm" RAID) by itself doesn't have any integrity checking.

In case one of the drives returns bad data[1] it may end up overwriting 
the good data on the other drives[2][3].

It's possible to add an integrity checking layer, but in my opinion at 
that point the whole setup becomes so complex one might as well be using 
btrfs or ZFS instead.

Both have built in integrity checking and can recover the data provided 
there is at least one good copy available[4], in addition to the many 
other features they bring (logical volume management, snapshots, 
copy-on-write, etc.).


For the avoidance of doubt, neither is a replacement for backups[5].


[1] Cosmic rays flipped a bit, bad drive, bad cable, bad controller, 
etc.

[2] https://unixsheikh.com/articles/battle-testing-zfs-btrfs-and-mdadm-dm.html

[3] A RAID 1 can have more than just 2 drives, it's just uncommon in 
home setups because of cost reasons.

[4] It's possible to use both btrfs and ZFS without redundancy. They 
will be able to tell your data is corrupted, but won't be able to 
recover it, of course.

[5] http://taobackup.com/

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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smartd peter@easthope.ca - 2022-01-22 19:30 +0100
  Re: smartd Dan Ritter <dsr@randomstring.org> - 2022-01-22 20:00 +0100
    Re: smartd peter@easthope.ca - 2022-01-23 16:50 +0100
    [SOLVED] Re: smartd peter@easthope.ca - 2022-02-04 18:20 +0100
  Re: smartd Andy Smith <andy@strugglers.net> - 2022-01-22 20:10 +0100
    Re: smartd peter@easthope.ca - 2022-01-23 07:00 +0100
      Re: smartd Andy Smith <andy@strugglers.net> - 2022-01-23 12:20 +0100
        Re: smartd Charles Curley <charlescurley@charlescurley.com> - 2022-01-23 16:20 +0100
          Re: smartd <tomas@tuxteam.de> - 2022-01-23 17:00 +0100
            Re: smartd rhkramer@gmail.com - 2022-01-24 18:20 +0100
    Re: smartd peter@easthope.ca - 2022-01-23 18:10 +0100
      Re: smartd Linux-Fan <Ma_Sys.ma@web.de> - 2022-01-23 19:20 +0100
        Re: smartd Andy Smith <andy@strugglers.net> - 2022-01-23 19:50 +0100
          Re: smartd Charles Curley <charlescurley@charlescurley.com> - 2022-01-23 22:20 +0100
        Re: smartd Andrei POPESCU <andreimpopescu@gmail.com> - 2022-01-25 10:50 +0100
    [SOLVED] Re: smartd peter@easthope.ca - 2022-02-04 19:10 +0100
  Re: smartd Charles Curley <charlescurley@charlescurley.com> - 2022-01-22 22:50 +0100

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