Hi Eric,
With apologies to others on the list if I'm responding with too much detail=
on this specific topic...
Yes, one external drive acts as primary storage for all media files (photog=
raphs, sound recordings, etc.) and gets backed up to each of 2 other identi=
cal external drives. My current drives are 6TB each, which is more than eno=
ugh for all the data I have. To be a bit more detailed, one of those backu=
ps is a straight clone and the second is an "incremental" backup, both main=
tained using Retrospect (more on this in a moment). The advantage of this =
approach is that the clone is a "warm" copy identical to the primary (excep=
t for any intervening work since the last backup, which as I mentioned is n=
ever more than 1 day's work), and thus ready to use immediately should the =
primary drive fail. The clone, however, only has the current version of ea=
ch file on disk. The 2nd "incremental" backup retains time history of any =
changed files, so for example, if a file is accidentally deleted or saved i=
n an unintended edited state, or is somehow corrupted, it is possible to go=
back and restore an earlier version of the file. This "incremental" backu=
p is, however, in a particular format specific to the backup software and t=
herefore needs to be restored to a clean disk before the data can be used. =
Having dual backups in this fashion gives the best of both worlds. The 3r=
d offsite backup is also incremental, and is swapped back and forth with it=
s onsite twin as often as possible.
(A small aside is that in this setup it is probably desirable to swap the p=
rimary drive and the "warm" clone from time to time, so that the run-time i=
s evened out between the two drives and the primary is therefore less likel=
y to fail. I have done this once over the course of 2 years or so.)
(Another small aside is that whenever I download new digital photographs or=
sound recordings, I perform the two backups immediately notwithstanding my=
1-or-2-times-per-day guideline before I do anything else to the files, and=
before I re-format the memory cards from the recorder/camera.)
As mentioned I am using Retrospect for both types of backup. At the time I=
chose it some years ago, it was considered the enterprise-class standard f=
or backup up Macintosh computers. Other than reputation, I picked it becau=
se it did some things I specifically needed which other software did not: =
network backups, backups of mixed Mac and PC machines, and it drives my Son=
y AIT drive which I use to back up selected data to tape. Retrospect has g=
one through several changes in corporate ownership, and I believe is now op=
erating as an independent company. There was one period where it seemed to=
be receiving minimal support, though as best I can tell that is no longer =
the case.
There are probably simpler solutions if you don't need any of the "corporat=
e" type features. If you are on a Mac, Time Machine would do a perfectly f=
ine job of the "incremental" backups and any one of a number of products (C=
arbon Copy Cloner for example) could manage the "warm" clone.
Incremental backups impose a storage overhead (to keep the earlier versions=
of the file), so if your working practices lead to large files changing re=
gularly (for example if regular metadata changes are saved within a media f=
ile), you may need to think about how this interplays with your backup stra=
tegy. The backup software which performs the incremental backups will allo=
w you to specify policies about how many past stages are retained and at wh=
at intervals.
There is nothing wrong with using a RAID configuration as the "primary" in =
this strategy -- in fact it would be an improvement over my approach in pro=
viding some level, albeit imperfect, of intra-day protection. I just didn'=
t go down this route again to keep the cost and complexity down. But I kno=
w people who are using Drobos, and others who are using G-Technology RAID b=
oxes, and are very happy with them. You just need to recognise they are no=
t a complete solution in themselves, and can be costly if they fail, as per=
my first note.
My units connect to my Mac tower by eSATA, but in today's world USB3 or Thu=
nderbolt would be better and more future-proof. As you say, any of these w=
ill be faster than Ethernet to a network storage box.
I am aware that you can construct RAID arrays in the way you suggest with s=
oftware, either with external devices or indeed with internal drives within=
your Mac/PC, but I do not have any direct experience with this approach.
I'm repeating what you already said to some degree, but there are indeed di=
fferent RAID strategies. As you said, RAID Level 1 is a mirror, and is oft=
en combined with RAID Level 0 ("striping"). RAID 0 often confuses people b=
ecause it has nothing to do with redundancy -- it simply spreads data acros=
s 2 or more drives for speed in access. Many of the larger capacity drives=
you can buy today (including the ones I have) in fact have 2 drives intern=
ally in a RAID 0 configuration for speed, but look like a single large driv=
e to the computer, and the RAID provides no backup protection. RAID Level =
1 (a mirror) is the most secure but least space-efficient of the redundant =
RAID configurations. RAID Level 5 is possibly a better choice for redundan=
cy -- in practice is is very secure and is much more space efficient than R=
AID 1.
Kin
--- In Eric Fassbender <> wrote:
>
> Hi Kin,
>
> I agree that there is still the element of the RAID server that can fail =
and in your case it has happened, so apparently it is not unlikely. So I re=
ally like your solution/approach. Am I assuming correctly that you use one =
drive that always stays the primary and that then gets backed up to the two=
other external drives? If so, what software are you using to perform this =
feat or do you do it manually? I would be very interested to hear your feed=
back as although I am still confident in my RAID, it has the limitation tha=
t it is slowed down by its only I/O connection - a 1GBit Ethernet connectio=
n. So I was eyeing a USB3 RAID solution using 2 or 3 standard external HDD =
and SoftRAID 4.5 (Mac), however, I am wondering whether your solution offer=
s any benefits over a software RAID?
>
> For anyone who is not that familiar with RAID systems, there are differen=
t types of RAID. What we need for data protection/safety is RAID 1, a 'Mirr=
ored Set'. This can be 2 or 3 even 4 drives and they all hold the same mirr=
ored data. So always check the specifications because there are many RAID s=
olutions out there that offer RAID 0, which makes data transfer super fast =
but does not offer protection against data loss. So if you are in the marke=
t, look for RAID 1.
>
> Cheers,
>
> Eric
>
>
> On 03/04/2013, at 7:49 PM, Kin Corning <> wrote:
>
> > I would offer some comments about using desktop RAID systems, which hav=
e been mentioned in this thread.
> >
> > When RAID arrays are used in Storage Area Networks or other such config=
urations in professional datacenters, *everything* is redundant -- the serv=
ers, the disk storage, power supplies, RAID controllers, and the interconne=
ctions between server and disk. In a desktop RAID unit, typically it is onl=
y the disk drives themselves which are protected. And, while a disk is the =
part most likely to fail, other failures can occur as well.
> >
> > I was reminded of these limitations the hard way a couple years ago whe=
n I had a desktop RAID unit fail, apparently (I'll never know for sure) due=
to a failed controller board in the box. The device was (just) out of warr=
anty, the manufacturer (a major well-known firm) would not offer any servic=
ing, and their only suggestion was to buy another identical unit, transfer =
the drives, and see if the data was intact. I did a fair bit of exploration=
and could not find any third-party who had the expertise to service the un=
it, which became an expensive scrap job.
> >
> > I was backed up separately, so my data was protected, but out of curios=
ity I contacted one of the best known firms in the UK for a quote on data r=
estoration, and the answer was =A33000 to give it a try with no guarantee o=
f success. This may sound crazy but is understandable given the complexity =
of how data is distributed across drives in the various RAID strategies, an=
d the fact that the data may or may not have been corrupted.
> >
> > These desktop RAID units may still be attractive to some in offering a =
degree of real-time protection against a drive failure, but in my own setup=
(used primarily for photography) I have concluded this benefit isn't worth=
the expense and complexity. I have moved to a simpler system with 4 identi=
cal large-capacity drives, 3 of which are onsite and 1 of which is always o=
ffsite. Every day (twice a day if I am doing a lot of work) the primary dri=
ve gets backed up to each of the 2 other onsite drives, and as often as is =
practical one is swapped with the offsite device, to keep the data protecte=
d from fire or burglary as up-to-date as possible. In this setup, I may los=
e a few hours of work if a drive fails, but on the other hand the system is=
instantly restorable and the cost of replacing the failed unit is much low=
er.
> >
> > Not to state what may be obvious, but if you choose to use one of these=
units notwithstanding, it is important to remember it is not a backup devi=
ce. RAID offers real-time protection against a drive failure, but an accide=
ntally-deleted file will be deleted across the RAID array, and any software=
-generated file corruption likewise may be duplicated in each 'copy' of the=
file. So even if you employ one of these units to protect your work intra-=
day, you still need to back up to separate devices regularly.
> >
> > Kin
> >
> > --- In "sounds.images" <sounds.images=
@> wrote:
> > >
> > >
> > > Many thanks everyone for you words of support and replies, a new lapt=
op has been ordered and I do have a caddy already, so will put it in ther a=
nd have a go at transferring it of it is possible to recover them..
> > >
> > > Seen in PC world.co.uk is a USB 3.0 1tb external drive for =A359.00 s=
o may grab one..
> > >
> > > Will update as soon as I can.
> > >
> > > Simon
> > >
> > >
> > >
> > >
> > > --- In "sounds.images" <sounds.imag=
es@> wrote:
> > > >
> > > > Last night the other half shut down the laptop as normal before bed=
. This morning it was dead. It would power on and fans would spin but nothi=
ng. Took it to my parents and tried their hard drive in my machine.... Noth=
ing..
> > > >
> > > > Tried my hd on their machine and it tried to boot but went straight=
to blue screen of death twice...
> > > >
> > > > So never put off your back ups. I have lost every recording I made =
since September. It was on the cards to do this little job this weekend, bu=
t it is too late.. Will try again when I get a replacement machine. This wa=
s completely unforeseen..
> > > >
> > > > Oh well... Lesson learned. Never put off the most important job of =
all.
> > > >
> > > > Simon.
> > > >
> > >
> >
> >
>
>
>
>
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