Re: how best to do
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>
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