[OSX-Users] Re: opinion: standalone smaill raid array

[Hugh Glaser]

Don't know if this is too detailed...

mc wanted backup.
I am not sure RAID is the cost-effective solution for backup.
Most of the problems Terry talks about such as the difficulty of migration
are more for server stuff.
I use a RAID in my server for TV programmes etc; I have an external disk (or
two) for general backup. I guess that is a similar configuration to Terry.
I'm not sure about your bandwidth problems over wifi, as I mostly use
gigabit round the house.
I did try using something like GFS on RH a while ago, but even then you end
up running out of slots on the server, so have to do a full migration (I
guess this is the Drobo solution, only better packaged).

For backup I use one disk for backup until it is too small; then I put it in
a box as an old archive and buy a new one. The way the price/Byte ratio
changes that seems to work.

One important principle here: never confuse backup and storage, or at least
be very clear about it all.
In particular if you start putting (just "temporarily" parking!) non-backup
stuff on the backup medium, you will end up unable to backup even that very
low-priority stuff (as Terry says).

Migration of backup is incredibly simple (take the old one offline, and give
it to a friend to look after, and start a new one).

So going more general than backup:

So I sort of do this:
Important stuff (documents, system, etc): proper backups (usually on
non-RAID disk), but on two sites, either by backing up at both places or
moving a backup.
Stuff I don't want to lose (iTunes, films): backup on one site, including
old archives.
Stuff I could lose (TV programmes primarily): RAID storage, no backup.

So for someone starting from scratch setting up a backup facility, I think
Time Capsule is actually a pretty good solution.
And if it is not secure enough, then adding an external disk to back up the
Time Capsule to is pretty cool.
I don't do this because I bought a server before Time Capsule came out, but
I suspect it all depends on what the existing configuration is.

Cheers
hugh

On 05/01/2010 22:36, "Terry R Payne" <trp at ecs.soton.ac.uk> wrote:

> On 5 Jan 2010, at 20:03, Philip Boulain wrote:
> 
>> Terry Payne wrote:
>>> Drobo is a propriety RAID system...
>> 
>> Dare I ask what the point of RAID in a *home* NAS is? RAID is good to keep
>> availability up for things like the ECS servers, but it's hardly a data
>> reliability mechanism when both drives are the same age from the same
>> manufacturer, likely from the same batch, subjected to the same load
>> patterns, mounted in the same physical case, hooked up to the same power
>> supply, and controlled by the same software.
> 
> The point of a RAID at home, and in particular - Drobo?
> 
> Simple!  I was fed up of migrating my iTunes archive from a 100Gb -> 220Gb ->
> 500 Gb, to then have a power-supply failure (not disc), which still scared the
> hell out of me.
> 
> Drobo gave me an incremental way of upgrading my capacity without the hassle
> of migration, and the *bonus* of getting some degree of safety given a single
> disc crash.  Is this the best way of getting protection?  Better than relying
> on a single disc, and when your archive is 1.7Tb (and growing), getting a disc
> for backup that is on average 2-3 times your working data size is can cost!
> 
> More to the point - having to buy potentially two new external discs each time
> I migrated started to be way too expensive.  Mebbie I'm taking a chance right
> now in *just* relying on the drobo, but I do have a copy of most of the
> valuable content on a separate disc.
> 
> Down the line I'll pick up a second Drobo to act as a mirror for my
> collection, but all in good time...
> 
> So the issue is - do you want expandable storage with some protection, or
> fixed storage with mirrored backup?  For the former - Drobo is a good option,
> the latter, Time Machine with a fat disc!
> 
>> Hugh's suggestion of a Time Capsule, or the also popular combination of
>> putting a big external drive on a Mac Mini, seems more practical to me; no
>> proprietary RAID hardware meddling with the disk layout and making it
>> unreadable by anything else.
> 
> It *all* depends on what you need!  If you are media rich (and also dynamic),
> then be careful with traditional backup systems.  I have an eyetv box which I
> use to record most the content I consume from the TV - this may get edited,
> and then exported to an iTunes archive.  If you assume a 1hour episode of some
> series or other is about 2-3Gb, and you record 4-6 hours of this content, then
> 12-16Gb per week could be recorded.  If you are faithfully backing this stuff
> up via Time Machine, then that is a lot of data potentially travelling over
> Wifi, and then filling up you backup archive (despite you watching the episode
> and deleting).  Best not to back this stuff up... but then what about that
> series you didn't get around to watching but downloaded the whole series for
> the winter???
> 
> A RAID gives me some protection, but without the hassle of finely tuning
> backup policies, or having to periodically maintain the backup archives.
> Incidentally, I also have a Time Machine archive which backs up the main disc
> activity, but it leaves the media archive to do its own thing.  Hmmm...
> different tools for different tasks....!
> 
> Look at your requirements and the options - don't just go with one or t'other
> option because of us evangelists, or cynical nay-sayers!
> 
> Terry
> 
>> 
> 
>> 
>> -- 
>> | Philip Boulain   PhD student | The human race will begin solving its |
>> | IAM, ECS, Uni of Southampton | problems  on the day  that it  ceases |
>> | http://zepler.net/~lionsphil | taking itself so seriously.-Discordia |
> 
> 
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