[DM-MUG] HD FW Storage, RAID or other ideas...

[Bryan Baker]

Good summary. Quick thought on (at least mirroring) A mirrored RAID  
is NOT a Backup - it is a redundancy which can act as a sort of  
backup against one or the other drives failing, but it is still not a  
backup. I know you already made the point well, but I wanted to add  
some emphasis.

there are also a couple newer varieties that are gaining popularity. 0 
+1 and 1+0 are variations (and I can't always remember which is  
which) of striping plus mirroring and iirc use at least 3 drives  
(much like raid 5) which is generally a good compromise of speed/ 
storage and redundancy. I think in one scenario you have a R0 Striped  
array that is mirrored to a 3rd drive (or perhaps another striped  
pair) and in another you have a mirror that is striped across  
multiple drives.

Now that I've put you all to sleep...

On Oct 23, 2006, at 9:53 AM, Jon Thompson wrote:

> Vicki,
>
> You may want to look at something such as a NAS (Network Attached  
> Storage).  While it is not something I would recommend for most  
> users, your storage needs are higher than most users, as well.  It  
> also will be utilized by more and more users as storage needs  
> increase.
>
> http://www.infrant.com
>
> You can get 2 TB (1.5 TB after RAID 5) for $2,339.  3TB (2.25 TB  
> after RAID 5) is $3,139.
>
>
> As for a short Primer on basic RAID so I am sure that you know what  
> the RAID numbers mean...
>
> RAID 0 - "Striping"  -  Part of any given file is written to each  
> drive.  _Very_ fast.  However, if you lose a drive you lose _all_  
> of your data.  Not what you want.
>
> RAID 1 - "Mirroring" - Your file is written to both drives  
> simultaneously.  You lose half of your storage (if you have two  
> 500GB hard drives, they will appear as one).  If one drive dies,  
> you still have the other.
>
> RAID 2,3,4 - not used, as they are less efficient or more costly  
> than the other types of RAID.
>
> RAID 5 - "Striping with distributed parity" - Your file is written  
> across all of the drives, except one.  On the extra drive, a parity  
> bit is generated.  What the parity bit does is allow the data to be  
> re-created if _one_ (and only one) drive fails.  RAID 5 is  
> computing intensive (which is why it is almost always done in  
> hardware, with dedicated chips), but gives you almost all of the  
> storage you pay for, without the risk with a single hard drive  
> failure.  (Technically, the parity bits are distributed across all  
> of the drives, as this increases throughput, but it is really  
> unimportant to a layperson.)
>
>
> In short, if you need pure speed for temporary data, use RAID 0.   
> If you have two drives - mirror.  If you have more than two drives  
> - RAID 5.
>
> Please note, RAID is also not a recommended solution for backup.   
> It provides safety from hard disk failure.  However, it does not  
> provide for user or computer errors.  If a file gets corrupt on a  
> RAID, it will _not_ be recoverable, just as if it gets corrupt on a  
> single drive.
> -- 
> Jon Thompson
> jthompson at greatapetrust.org
> 515.360.1351
>
> Insights through collaborations with apes
> Great Ape Trust of Iowa
> www.greatapetrust.org
>
>
>
> On 2006, Oct 23, at 1:58 AM, Victoria L. Herring wrote:
>
>> Thanks much for the links.  I'll check them out too...The idea of  
>> a swappable batch of drives comes because I have a proliferation  
>> of LaCies FW HDs all over my desk and not only is that clutter,  
>> but it makes it hard to remember where to find things etc.   
>> Aperture will let you have one library and portions over external  
>> drives unhooked til you need them [apparently] which would be  
>> perfect....more later as I research.
>> -- 
>> Victoria L. Herring, Attorney, Civil Rights, Discrimination &  
>> Employment Law, <http://www.HerringLaw.com>;  Travel research,  
>> planning & Photography, <http://www.JourneyZing.com>;  Des Moines,  
>> Iowa, ph.515-255-4475.
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--
Bryan Baker
President
Des Moines Macintosh Users Group
http://www.dmmug.org
president at dmmug.org