On Wednesday 28 July 2021 11:04:59 Dan Ritter wrote: on list, I am subbed. > Gene Heskett wrote: > > Greetings all; > > > > This, my main machine that backs up 5 others here, but does that > > with drives not involved with daily stuffs, and of course I'm > > gradually replacing spinning rust with SSD's. > > > > I've been dragging my feet on updating from stretch to buster, > > waiting for 1TB SSD's to get affordable. Now they almost have. > > > > But I do have a pair of 500 GB SamSung EVO 860's and one empty sata > > socket. Spares for the rest of my multi-machine farm, currently at 5 > > other machines. > > > > Total storage actually used on this machine ATM is around 318G. Some > > of which isn't precious. > > > > With 2 drives and 2 sata connectors, how can I configure this for > > maximum redundancy, but not necessarily maximum working capacity? > > Best redundancy is a RAID-1 mirror: everything written to one is > also written to the other; reads are handled by both > simultaneously. You get about the same write performance, much > better read performance, and one of them dying doesn't kill your > data. > > However, if you don't need second-by-second simultaneity, you > could just set up a cron job to rsync your first drive to your > second drive once an hour or twice a day or overnight. > > > Does that recommendation change if I order 2 more 1T SSD's? In which > > case, which of the current buzzwords tech is the most dependable? > > Do you have an available PCI or PCIe slot? > > The standard SATA interface is one port, one drive. (There are > exceptions which are not worth talking about here.) If you can > plug in a fairly cheap PCIe to SATA card, you can get 2 or 4 or > 8 more connectors. > I have spares of both the very short slot and the longer slot, whatever it is, this is an Asus Prime X370-A II motherboard, so name the preferred poison for a new sata card. > Your choices for 4 drives are: > > RAID10: write 2 copies to four drives, read from all four; > capacity is 2 drives worth. Survive any one drive failing and > also survive two drives failing if they are on different > stripes. > > RAID6: write one copy plus two sets of parity information to > four drives, read from all four to reconstruct data. Speed is > equivalent to one drive. You can survive any two drives failing.
Raid6 sounds promising. Equivalent capacity is also one drive? > > All of these can be handled in software by the kernel, managed > by mdadm. You can easily transfer the drives to some other Linux > box. Name the poison card, and I'll get it and 4 more drives as this tower has lots of empty drive space suitable for hiding SSD's. > -dsr- Thanks dsr. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>
