Re: how best to do
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.
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.
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.
-dsr-
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