My laptop is running on fumes. The battery is failing, and the Linux root
partition has already gone south. I need a new computer.

I am a geek in every sense of the word except one: actually having geek skills.
I have a background in computer programming, but I can't keep up with modern
software, and as for hardware, I barely know a wrench from a screwdriver.
Friends, knowing my computer background, have asked me for recommendations, but
I frankly have never had a clue. In my last job, I was asked to design a
disaster recovery plan, and slammed head-on into the Peter Principle. Since
then, the world of technology has rapidly passed me by. I need help.

My brother is not a trained computer professional, but he uses them extensively
for business. In terms of recommending a computer setup, he's way ahead of me.
Yet, I have to take his recommendations with a grain of salt. OK, maybe a
bagful.

My brother can't understand why I settle for an external backup disk. He says,
RAID, RAID, RAID, all the way. He doesn't lose a keystroke after an equipment
failure, and he sees no use for external backups. So I'm looking into RAID,
specifically for how it can work with a dual-boot Windows/Linux system. What
I've read for Linux is most emphatically that RAID must not be used as a primary
backup system. I carried my concerns to my brother, and he's thought of all
that. Except that his solutions are all Microsoft, Microsoft, Microsoft, and
Microsoft is bad for my mental health.

My brother is giving me the impression that he thinks external backups are a
stupid idea. I don't feel comfortable without an external backup; however, if I
do have an external backup, I don't see why I would need a RAID. Sure, without
RAID, I can lose a few hours or a few days of work, but for my current
(non-professional) needs, would that justify the extra expense of a RAID?

For the past decade or so, I have only used laptops at home. Power blackouts are
frequent in my community, and laptops seemed the ideal way to get around that.
However, my brother says that with my heavy computer usage, I should have a
desktop system, and just buy a cheap laptop for traveling. Does this sound like
a reasonable arrangement? I did have a battery backup, but it didn't take long
for it to fail in my environment. Should I just resign myself to buying a new
battery backup every couple of years?

The overarching message that I get from my brother is that I'm doing it wrong.
Whether it be gardening, cooking, stargazing, or choosing a computer operating
system that is not Microsoft, I'm doing it wrong. Oh, and did I mention that
he's a die-hard Microsoft Windows apologist?

I'm waiting for a phone call from a technician at the computer store to discuss
my options. I really need other opinions before I make a decision!

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Oh, one more thing, is 64 bits recommended for POV-Ray?

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Le 23/01/2013 16:09, Cousin Ricky a écrit :
> for Linux is most emphatically that RAID must not be used as a primary
> backup system.

If you expect RAID to cover failure, you would be in for deception.

My home system is Raid5, linux only. It should support failure of one
disk, but I know that two failures at the same time will just lost all
the content (of 5 drives). I keep an external backup (offline, over usb)
just in case (sync is low).

About raid, there is two cases: done by the motherboard, or only by the OS.

My motherboard is able to set some raid... but it fails once the usage
goes beyond 2 TB... (well, not fails, just corrupt... )

So, I went the pure-OS way. It's fine with ubuntu once you have found
the right iso & right steps (including the small step: allow to boot on
a damaged raid array, which is not set by default, so the raid can
continue to run in degraded state, but if you turn off the system,
you're dead if you had not repaired before the shut-down)

Now, for your setting: assuming your motherboard would support raid,
that you are willing to pay an extra drive (for nothing, in capacity),
you can:
* make a basic raid-1 (mirror) system via the motherboard, should one
drive fails, you turn the live one in non-raid and use it... transparent
to both Microsoft & Linux, but beware of the size limit. Cost: 2 drives
for the capacity of only one.

* make a motherboard raid-5 system (need at least 3 disks, more is
better), got the capacity of N-1 drives (and a descent speed too, due to
parallel read & write, for big files). Beware of size limit, can be
fine, and transparent to the Windows & Linux, so handling fault is only
a bios business. BUT you cannot have more than one fault at a time, and
if the motherboard dies, the disks might not be recoverable at all.
(unless you find exactly the same bios... good luck after 4 years..)

* Stop using windows and single boot Linux in softraid: no more size
limits, but still vulnerable to multiple failures at once (in raid 5).
At least, motherboard changes is transparent.

I do not know how to have windows on raid, when not done by the
motherboard (and re-installing windows on a pre-build system to turn it
on Raid can be troublesome).

If you intend to use SDD, do not go raid!

If you have a usage for a laptop, synchronising it with a desktop can be
painful on the long run. And external drive are the best backup for laptop.

PS: raid-6 is not worth the slowdown & complexity, unless your data is
very precious and you are ready to have 2 wasted disks.

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On 01/23/2013 10:41 AM, Le_Forgeron wrote:
> Le 23/01/2013 16:09, Cousin Ricky a écrit :
>> for Linux is most emphatically that RAID must not be used as a primary
>> backup system.
>
> If you expect RAID to cover failure, you would be in for deception.

/generally/ speaking that would be false, but yep I agree with you on 
this, as I've seen failures involving two different mechanisms and 
recovery was problematic ... worst case scenario who be a failure that 
also involved loss of the parity compressed data. In a /perfect/ world 
RAID5 is a valid option.

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James Holsenback <nom### [at] nonecom> wrote:
>  In a /perfect/ world
> RAID5 is a valid option.

In a /perfect/ world, RAID would not be necessary at all.  Backups, neither.

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On 01/23/2013 11:47 AM, Cousin Ricky wrote:
> James Holsenback <nom### [at] nonecom> wrote:
>>   In a /perfect/ world
>> RAID5 is a valid option.
>
> In a /perfect/ world, RAID would not be necessary at all.  Backups, neither.
>
>
LOL ... I didn't mean that quite so literally

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On Wed, 23 Jan 2013 10:09:00 -0500, Cousin Ricky wrote:

> My laptop is running on fumes. The battery is failing, and the Linux
> root partition has already gone south. I need a new computer.

I didn't realize there were others who crossed over from here to the 
Linux forums I admin (but I recognise your post from over there <g>).

I don't know that I'd worry too much about RAID - it tends to add 
expense, and most of the machines I've had for personal use have not used 
RAID for redundancy.  I /do/ back stuff up to an external 2 TB drive so I 
maintain two copies of the data that's important to me, and that's proven 
effective through multiple hard drive failures (oddly, mostly on the 
device that's backed up to rather than the "source" machines).  I've lost 
some non-critical data, but that's OK, because it was non-critical.

Cost of RAID has come down significantly with SATA/PATA RAID controllers 
in consumer-grade machines, but it still seems like overkill to me for a 
personal machine.  (My last home RAID system was a Compaq server-class 
486 that I bought in 1992 or so, and Compaq graciously gifted me a SMART 
controller and a couple of 2 GB drives in exchange for some volunteer 
work I did for them on CompuServe so I could run and support customers 
using their RAID controllers).

Jim

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On Wed, 23 Jan 2013 11:35:09 -0500, James Holsenback wrote:

> On 01/23/2013 10:41 AM, Le_Forgeron wrote:
>> Le 23/01/2013 16:09, Cousin Ricky a écrit :
>>> for Linux is most emphatically that RAID must not be used as a primary
>>> backup system.
>>
>> If you expect RAID to cover failure, you would be in for deception.
> 
> /generally/ speaking that would be false, but yep I agree with you on
> this, as I've seen failures involving two different mechanisms and
> recovery was problematic ... worst case scenario who be a failure that
> also involved loss of the parity compressed data. In a /perfect/ world
> RAID5 is a valid option.

Oh yes, I would agree as well.  The Compaq SMART controller I just 
mentioned in response to Ricky had multiple two-drive failures (caused by 
inadequate cooling at the end of the hardware's useful life).

Less likely is if you have a hot spare (which the newer SMART controllers 
supported 10 years ago) or mirrored RAID-5 (sometimes called RAID10, 
sometimes called RAID15 - there was no industry standard at the time for 
what it was called).

It's all about mitigating risk, and to do that, you have to consider MTBF 
and the environment the hardware is in (and how that is likely to affect 
MTBF).

Jim

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> My brother can't understand why I settle for an external backup disk. He says,
> RAID, RAID, RAID, all the way. He doesn't lose a keystroke after an equipment
> failure, and he sees no use for external backups.

It depends how much you value the work you would potentially lose 
between backups. For me personally I don't generate enough "work" on my 
home machine between backups (usually once per week) to justify the 
complexity, expense and education needed for running a RAID system. The 
other benefit of external backup is that you can take it to another 
machine very easily at any point. The other thing I do is to put a small 
number of critical files encrypted in a special folder that is then 
sync'd with a couple of online file storage sites. In case my HD and 
external fail together (eg huge power surge, house fire, flooding or 
some other disaster) then at least I don't lose the really important stuff.

> For the past decade or so, I have only used laptops at home. Power blackouts are
> frequent in my community, and laptops seemed the ideal way to get around that.
> However, my brother says that with my heavy computer usage, I should have a
> desktop system, and just buy a cheap laptop for traveling. Does this sound like
> a reasonable arrangement? I did have a battery backup, but it didn't take long
> for it to fail in my environment. Should I just resign myself to buying a new
> battery backup every couple of years?

Depends how often you get power outages, how long they are for and what 
you want to do on your computer during them. A powerful laptop running 
POV flat out will likely not even last an hour on battery, but if you 
just want email/web access you can get ones that will last 6 hours+. I'm 
happy with just a desktop because if there is a power outage I can still 
use my phone for web/email.

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Am 23.01.2013 16:09, schrieb Cousin Ricky:

> My brother is giving me the impression that he thinks external backups are a
> stupid idea. I don't feel comfortable without an external backup; however, if I
> do have an external backup, I don't see why I would need a RAID. Sure, without
> RAID, I can lose a few hours or a few days of work, but for my current
> (non-professional) needs, would that justify the extra expense of a RAID?

Think about it:

A RAID lets you continue work in case of a hard disk failure as if 
nothing had happened.

An external backup lets you restore most your data - but not the most 
recent stuff, and not in just a moment's notice - in case of a hard disk 
failure, a power surge that fries your whole computer, or - depending 
where you keep it - even a fire.

What's the thing you really want? What's the thing you really need? What 
are you willing to pay for it?

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