On Monday 27 Oct 2014 15:15:22 James wrote:
> Rich Freeman <rich0 <at> gentoo.org> writes:
> > > On 27/10/2014 11:24, Mick wrote:
> > >>> With a caveat: if an ssd dies, it will die suddenly. Without warning.
> 
> With SSD the most important fact to keep constantly in mind is
> writing/erasing by blocks due to uniqueness of the hardware.
> Unfortunately, if you dig deeply, many Solid State Storage devices
> are organized differently and those hardware differences may impact
> your SSD_specific implementation  details. SSD raid redundancy is
> something most machines (folks) cannot afford, imho and may be a waist
> to dis_functional if you employ the same semantics for I/O on the
> redundant SSD hardware.
> 
> [1]
> http://codecapsule.com/2014/02/12/coding-for-ssds-part-6-a-summary-what-eve
> ry-programmer-should-know-about-solid-state-drives/
> 
> > >>  In such cases I am prepared to live with the risk of some
> > >> 
> > >> data loss, on machines where raid is not an option.
> 
> Wise with a well thought out (planned) recovery/fresh-install strategy.
> 
> > > Without some form of redundancy that would be your best strategy -
> > > decent and frequent backups
> > 
> > But yes, backup and RAID are really your only options for SSD failure
> > as far as I can see it. That and limiting the amount of data that
> > can't be re-generated.  If you just save the world file and all of
> > /etc you could probably rebuild a Gentoo install fairly quickly on a
> > new drive, and then you're just left with /home and whatever else you
> > happen to have installed that sticks stuff in /var that you care
> > about.
> 
> Yep. Rich has it exactly right.  I'd add /usr/local/*
> as by design that is where I put most uniqueness in any linux system
> besides the list above.
> 
> In fact for small networks, I just identify the directories that I want
> to preserve. At the least you rsysnc those to a differnet system
> on the local net, besides a backup, if no raid is underneath. (Triple).
> Obviously, you have all systems on UPS power......?
> 
> I'd add any dirs with custom scripts and the kernel  files also minimally
> replicated to another system. A comprehensive list of critical files
> is fine. Workstations and servers have different lists of critial files;
> and you can further subdivide the servers by function, to focus
> on those critical files and directories. So what is on the SSD that is
> important, just replicate it to a spinning HD on the local net. None
> of this replaces weekly backups, but give you a tertiary level of
> recovery redundancy for the important stuff. Triple redundancy is keenly
> important for all critical stuff; ymmv.
> 
> Personally, I find max-ram and spinning HD to be the best bang for the
> buck. But, many folks with older portables are usually really happy with
> SSD as a replacement (single) drive that is cost effective but needs
> a network backup.
> 
> [2]
> http://serverfault.com/questions/454775/is-post-sudden-power-loss-filesyste
> m-corruption-on-an-ssd-drives-ext3-partition
> 
> 
> hth,
> James

Good comments and links James.  Thank you.

-- 
Regards,
Mick