Raid vs rsync -

[Bob Goodwin]

On 03/09/15 20:23, Sam Varshavchik wrote:
> Bob Goodwin writes:
>
>> I had a mainboard fail in a box I use as a server, I moved the hard 
>> drive into old computer and carried on from there. Now I've replaced 
>> the board and intended to set it up using Raid to mirror two drives. 
>> However I have been wondering if it wouldn't work just as well to 
>> periodically rsync the drive in use with a second drive?
>>
>> That seems a more direct approach and I could easily check to make 
>> certain that the second drive was a usable copy, insurance against 
>> loss of data.
>>
>> Am I going wrong somewhere in my thinking?
>
> Raid, and rsyncing, are not equivalent to each other. They solve 
> different problems.
>
> For starters, in your case taking an existing partition and turning it 
> into a RAID volume is going to be a big project. You'll have to back 
> up your existing data somewhere, erase the existing partition, create 
> a raid partition, then restore your data from backups. I'm not aware 
> of a way to turn an existing non-RAID partition into a RAID one.
I had intended to set up the raid server first and then transfer data 
from the original drive, that seemed like it should would work?

And yes, I think rsync is really what I want anyway since I'm more 
interested in saving the data in two places to minimize the chance of 
losing everything with a failure of some kind. I realize there is a 
chance of losing some data depending on when the failure occurs relative 
to the last rsync and I'm willing to accept that. My files are important 
to me but not so critical that I need to cover every possibility.
>
> rsync is easier to set up when you have existing data, and I do have a 
> few laptops where I have a daily job to rsync their data onto a 
> different server.
I have been using rsync to make copies of files between several 
computers for some time and it works without a hitch for me ...
>
> On the other hand, RAID is generally faster, and runs in realtime. 
> With rsync, you do have some window of vulnerability where you will 
> lose everything since your last rsync run, when you have a failure, 
> where RAID provides up to the second redundancy.
>
So it looks like that is a reasonable thing to try. I've set up the NFS 
server and will transfer some data into it tomorrow.

Thanks for the advice,

Bob

-- 
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