[GLLUG] Software RAID advice

[Chris Bell]

On Saturday, 6 January 2018 16:42:28 GMT John Winters via GLLUG wrote:
> On 06/01/18 15:02, Imran Chaudhry via GLLUG wrote:
> > I'm setting up a new server which I'm going to be sysadmining on an
> > ad-hoc basis.
> > 

Linux has not always been able to boot from RAID, although RAID1 is usually 
OK. Whether or not they are RAID, I usually have one partition as the current 
system partition "/" , another formatted and named ("/future") but not used at 
present, and another ("/srv") with symlinks as required, such as from "/home", 
plus the usual "/swap". This allows me to install the next major distribution 
upgrade in "/future", with the old "/" now listed in /etc/fstab as "/old". You 
will find that /swap and the original /future will be re-formatted and given 
different ID's, but you can now examine the new /etc/fstab and then edit the   
/old/etc/fstab to suit, leaving both old and new bootable while you configure 
the new /.
Beware that any crash or power failure will force the next boot to be in 
single mode until the RAID system has compared the parts (in the background) 
and ensured that they match, so you may wish to consider a UPS.
A rackmount box will usually be designed so that it remains cool even when 
squeezed in between other boxes creating lots of heat, and will generate more 
noise than a free-standing tower case with the power supply and its fan near 
the top.
Top of the range hard drives may spin faster and could produce more noise, 
although some are designed to be used as just one of many together, where 
there is a risk of combined resonance effects causing early failure, so more 
care is taken over bearing design.
"Green" drives that spin down until required have a bit of a bad reputation 
because of the much greater number of spin-up causing early failures, the only 
failure I have had recently was one of a pair of "green" RAID drives.  

-- 
Chris Bell
Website http://chrisbell.org.uk