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
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