[Coco] working with the sdc

[Gene Heskett]

On Monday 05 November 2018 09:44:57 rietveld rietveld wrote:

> If you are interested in using the SDC to launch DW I can send u a.
> Dsk that contains the modified HDBDOS DW.    You just place the. Dsk
> on the root of the SD card. Then open the. Dsk and launch dW
>
I'd intend that it would boot nitros9 at powerup if thats possible, but I 
see a problem. Since LSN0 needs to be updated each time you select a 
different os9boot file that (AIUI) 4k block will need to be erased, and 
a master copy from someplace else on the sdc, needs to be written back 
to track 0 with those 5 bytes being edited on the fly. My bootlink, nor 
the basic version on vdisk-0 of my present setup doesn't do that since 
it assumes a hard disk with unlimited read/modify/write cycles ability. 
Once up and running, I can fix my "bootlink" to do that, but that brings 
up the question of how many such erase/re-write cycles can we expect a 
modern sd card to survive?

Interesting question.  And one that points to a wish for the sdc, 
modified to use a sata drive since prices there are in freefall. I can 
by SSD's of 40 to 60 Gb for around $30, which is plenty big enough to 
run LinuxCNC from, so I'm replaceing all the spinning rust drives as 
they fail with those SSD's, gaining speed that makes the machine load 
and run whatever with a dual core cpu running at 1400 Mhz, act like its 
a quad core running at 10 GHz.

So Ed, since I know you are copying the mail, whats chances of a new sdc 
pack, with the sdc socket space swapped for a sata socket or 2?

These modern SSD's  do all that management and wear leveling internally, 
and my busiest machine isn't aware of a spare block re-assignment so far 
in around 2 years. Although I do see a fudged value from the 
power-on-hour column for both of the drives running right now, one says 
89xx hours, just into the 2nd year, and I know its longer than that, and 
the other is reporting a number thats about the age of the known 
universe, and neither is reporting a swapped block.
So just for grins I've initiated a -t long self test that will smell 
every corner it has on both of them. 

-- 
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)
Genes Web page <http://geneslinuxbox.net:6309/gene>