Le 2013-01-23 14:30, Jim Henderson a écrit :
> 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).
>

If it's anything like the Compaq SMARTArray failures I've seen, the 
problem was EMI on the Proliand drive bay backplanes that made the 
controller receive garbled data, so it declared the disks bad, even 
though they were perfectly fine.  We had Compaq go and manually reset 
the disks to "good" status - using proprietary hardware - to recover 
some of the data after we had threatened to take our business elsewhere 
since we had had 7 or 8 RAID array failures in less than a month.

They also replace all our Proliant drive bays (60 of them, across North 
America) for a more recent revision number of the backplane.  Our 
carefull inspection revealed the "Rev. D" boards had two extra 
capacitors, and a huge ferrite core around the SCSI cable.

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I'm *certainly* no expert on RAID (in fact, I had to look up the modern meaning
of the term before posting this.) But from the comments here, and a quick
overview on Wikipedia, it seems to me that RAID arrays are really meant for
'professional' environments, where there is either a lot of data to constantly
backup, or the data is super-critical (from a business point of view.) Or the
user perceives it to be so. I do understand that some typical *home* users might
find such a thing beneficial for one reason or another; but the cost of external
backup drives--even multiple ones--is now so low (and the technical saavy needed
to use them is also low), that I'm curious as to RAID's practical use in a home
environment--given the OP's statement that the data he wants to backup is just
his typical home stuff. True, a RAID array allows instantaneous backup and
recovery of data AFAIU; but losing, say, only a week's worth of 'home' data
between (non-RAID) backups doesn't seem so terribly catastrophic. That's
debatable, of course!!

I suppose my opinion of this is based more than a little bit on my own
perception of the complexity of setting up a RAID array (in Windows), vs. using
simple external USB drives.

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Le 24/01/2013 15:57, Kenneth a écrit :
> I do understand that some typical *home* users might
> find such a thing beneficial for one reason or another; but the cost of external
> backup drives--even multiple ones--is now so low (and the technical saavy needed
> to use them is also low), that I'm curious as to RAID's practical use in a home
> environment--given the OP's statement that the data he wants to backup is just
> his typical home stuff.

Well, My home computer is loaded with 3TB of data (a few GB for the
system, all the remaining for audio, video, photos, emails & a bit of
povray... I do not want to bother managing the space: until I delete it,
I want to be able to retrieve it )

Backup on external virgin drive took more than 2 days to perform.
(and so far, I'm lucky, 3TB external drives do exist, and rsync is able
to continue from previous run)
updating backup (using rsync) take less time (but still a bit), but I'm
lazy so I do it once in a while. Nevertheless, I want to be protected
against a single drive failure (and as I do not want to manage the
space, I had to just see "one big space", so raid was already an option,
such as raid0 (concatenation of all disks as a single partition)).
So, instead of 5 disks, I bought a sixth one and setup a raid-5.
increase of disk prices is about the VAT, I can pay it twice for such
comfort... (and it was before the water over the factories in Asia, so
prices were even cheaper than a few months ago)

Now, would I split the backup across multiple backup drive ? Not as a
starter. I probably will have to do it one day, but it will bother me to
actually have to manage the directories (which one is big enough to fit ?).

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On Thu, 24 Jan 2013 09:12:26 -0500, Francois Labreque wrote:

> Le 2013-01-23 14:30, Jim Henderson a écrit :
>> 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).
>>
>>
> If it's anything like the Compaq SMARTArray failures I've seen, the
> problem was EMI on the Proliand drive bay backplanes that made the
> controller receive garbled data, so it declared the disks bad, even
> though they were perfectly fine.  We had Compaq go and manually reset
> the disks to "good" status - using proprietary hardware - to recover
> some of the data after we had threatened to take our business elsewhere
> since we had had 7 or 8 RAID array failures in less than a month.

The server was a Prosignia, but that's quite possible, too, I suppose.  I 
no longer have the system, but I do recall that the cooling in the room 
wasn't very good (it was my house, but the computer room was a southern-
facing room here in Utah, and the problems were always during the summer 
months).  Oh, and the power was intermittent in the system as well, so it 
could've been a bad PSU.

Jim

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On Thu, 24 Jan 2013 09:57:36 -0500, Kenneth wrote:

> I suppose my opinion of this is based more than a little bit on my own
> perception of the complexity of setting up a RAID array (in Windows),
> vs. using simple external USB drives.

Software RAID is certainly not a solution I'd use except in a pinch.  The 
overhead is too great.

HW RAID is a better solution, but also has its own issues with throughput 
bottlenecks (5+ drives on a single controller = massive need for 
bandwidth to the controller, and most don't have it, so your performance 
drops).

Jim

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On Thu, 24 Jan 2013 17:08:52 +0100, Le_Forgeron wrote:

> updating backup (using rsync) take less time (but still a bit), but I'm
> lazy so I do it once in a while.

One word:  cron. :)

Jim

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Jim Henderson <nos### [at] nospamcom> wrote:
> One word:  cron. :)

Not in my community.  That's a good way to fry the backup disk.

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On 01/25/2013 11:37 AM, Cousin Ricky wrote:
> Jim Henderson <nos### [at] nospamcom> wrote:
>> One word:  cron. :)
>
> Not in my community.  That's a good way to fry the backup disk.
>
>
LOL ... What??!!??

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On Fri, 25 Jan 2013 11:37:56 -0500, Cousin Ricky wrote:

> Jim Henderson <nos### [at] nospamcom> wrote:
>> One word:  cron. :)
> 
> Not in my community.  That's a good way to fry the backup disk.

Depends on the options used.  For example, if the purpose is to back up 
data, using it to mirror data would be counterproductive.

But the data needs to get on the backup drive somehow - using cron + rsync 
gets it there with a minimum of hassle and only writes the changes.

Jim

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Having a RAID system is no help whatsoever if the actual RAID controller 
dies on you.

True story, learned the hard way... ;-)



For a home setup, I would suggest that RAID is way overkill, and a 
simple offline backup now and then is what you actually want. RAID might 
save you in the extremely unlikely event of a drive failure. (It 
basically means you don't have to wait until you can purchase another 
drive.) But a backup will save you from any possible type of failure. 
(Except failure of the backup medium itself. Having two backups fixes 
that...)

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