RSYNC Fedora

[Eric J. Feldhusen]

On Nov 25, 2003, at 8:47 PM, William Hooper wrote:
> Scott Burns  said:
>> Dan Goodes wrote:
>>
>>> Just to clarify here, we (PlanetMirror) lost a number of disks in a 
>>> raid
>>> array, and are working on restoring service. As you noted, this means
>>> that RH and Fedora are missing, among others (albeit temporarily, 
>>> but I don't
>>> have an ETA at this stage).
>>>
>> Still offtopic, but I read the informix newsgroup, and there is a
>> resident who posts regularly on the evils of RAID5 - mainly that no
>> matter how many disks you have, if two disks die, the second before 
>> the
>> recovery of the first is complete, you lose everything.  I'm just
>> curious to see if you used RAID5?
>
> Of course if both disks of a mirror set die you lose everything, too.

In both cases, you can using either linux software raid or most 
hardware raid cards have it, is have one, two, or more hot spares as 
part of the raid.

Example,

A computer with 4 - 100GB hard drives in a RAID 1 (mirroring), set up a 
mirror with 2 hot spares. Total storage - 100GB, but you can have 3 
drive failures and the system can keep running.

A computer with 4 - 100GB hard drives in a RAID 5 (parity) set up, 3 
drives are active in the RAID 5, 1 hot spare drive, Total storage 
200GB, actually a little less due to overhead. In this configuration, 
one of the drives in the raid fails, the hot spare becomes active, the 
raid rebuilds, and you replace the dead drive with a fresh drive and 
this drive becomes the hot spare.  In this case, you can have 2 drives 
fail and the system can keep going.

If you want to do something like this, I recommend 3ware raid cards, 
this is how I have my file/print servers running samba working at the 
schools I work at.

Eric Feldhusen