Re: Partitioning of new machine

[Patrick Bartek <nemommxiv@gmail.com>]

On Sat, 09 Aug 2014, B. M. wrote:

> Le 9 août 2014 à 05:44, Patrick Bartek <nemommxiv@gmail.com> a écrit :
> 
> > On Fri, 08 Aug 2014, B. M. wrote:
> > 
> >> Hi all,
> >> 
> [snip]
> >> 
> >> What do you think about the following:
> >> 
> >> === SSD: ===
> >> /boot           unencrypted, 300 MB
> >> /               ext4, encrypted, 25-30 GB
> >> /home           ext4, encrypted, keyfile, 220-225 GB
> >> User data for two users
> > 
> > I wouldn't put /home on the SSD.  With all the writes involved,
> > better to put it on a spinning disk.  And by doing that, you don't
> > need such a huge SSD.  64 to 100GB will more than do with
> > just /boot and / on it.
> 
> Well, my plan is to put /home on it, but without all database-related
> stuff (e.g. digikam db) and iceweasel gets a cache size of 0. Maybe I
> also move the downloads directory to the HDD together with one for
> virtual machines. I don't think that there is much left which is
> written so often, but maybe I'm wrong?

Of course, it's your system, and you can configure it anyway you
please, but you did ask for advice.  However....

Why do you want /home on the SSD anyway?  The main advantage of an SSD
(on a desktop) is speed.  Fast reads and writes.  You've removed
everything from /home that would take advantage of that speed.  All
that's left is user and app configs, trash, thumbnails, etc.  Nothing
that requires speedy response.  So, there's no reason to have /home
there.

 
> > [snip] 
> > 
> > I wouldn't use btrfs.  It's not ready for primetime, yet.  Maybe,
> > in a few years.  Stick with ext4.  It's proven and rock solid.  If
> > you want to "play" with brtfs, okay, but don't put any important
> > files on it.
> > 
> > Also ...  You're RAID 1-ing two partitions on the SAME physical
> > drive? For "auto-backup," I assume?  Bad idea. If your one hard
> > drive fails, both those RAIDed partitions are toast.  Put one of
> > those partitions on another HD.
> > 
> > You might also look into using LVM instead of traditional
> > partitioning, particularly if you plan on adding more hard drives.
> 
> OK, I didn't mention that before, but my complete setup additionally
> includes an external backup drive (of course) with hourly backups
> of /etc and /home on one partition and a large second partition for
> the backup of /data, so for /data I have the btrfs RAID1 internally
> on the same drive which protects against bit rot plus one external
> partition (so without RAID-redundancy) to protect against hardware
> failure. I'm unsure if I should stick with ext4 for the external
> backup because btrfs's integrated check summing is so appealing
> (again the bit rot problem), but then there would still be the risk
> of fs failures due to its experimental state - but as far as I found
> out so far, btrfs should be ready as long as one doesn't use
> snapshots and RAID 5+; its basic functionality seems to be safe.

If you're backing up those RAIDed partitions hourly, you don't need
RAID in the first place.  As others here have mentioned:  RAIDed
partitions should be on different drives.

And as far as btrfs is concerned:  Even its developers don't recommend
using it on production systems.  It's not stable enough, yet.  That's
why it's called "experimental."  Use at your own risk.

> Currently I'm using LVM, but I'd like to get rid of this additional
> complexity and keep things relatively simple.

LVM does have its advantages, but I don't use it since I have no need
for those advantages. Traditional partitioning works fine for me.

I mentioned it because you talked about adding hard drives in the future
to expand storage.  With LVM, it's simple to add another drive (or more)
to LVM'd drives.

> Having a RAID1 on two partitions on the same disk is bad for r/w
> performance, that's clear, but it's only for my photo archive which I
> don't access so often (and writes are even less frequent); the
> working part would reside inside /home, i.e. on the SSD (ext4).

Poor performance?  Yes.  But more disadvantageous, it'll beat the drive
head to death.

> The alternative would be to put another HDD in the machine and set it
> up as a RAID, but then my wife might complain about the additional
> noise...

What additional noise?  My 8 year old system with two hard drives and
three fans is VERY quiet even sitting next to it.  2 meters away?
Barely audible.  Of course, I used 125mm low speed, high volume fans.
The CPU has an oversized fan, too. It's small, fast spinning fans that
make noise, not hard drives.  Unless, they're going bad.


B