Some questions about RAM disk

[arnljot]

These questions might have been asked before. But search is overrated

1) What filesystem does "Ram Disk" use, aka RAM:

1: I assume it uses FFS?The reason why I'm asking is because I'm pondering max file name length issues. FFS vs. SFS, and temp storage in RAM. As I can recall, 32 is FFS, and 107 is SFS? So names might be truncated when moved from disk to RAM and back?

2) What size does "Ram Disk" have?

2: I assume that it grows dynamically? That it eats chunks of Ram, and frees RAM as it needs to store it's contents. And that it uses FAST RAM first, then Chip?

3) How is "Ram Disk" created?

3: I have no clue, I remember the "RAD:" The Recoverable RAM Disk. That has a mount entry in the mountlist (pre 2.0) and it's own Mount script in Dosdrivers since. But Ram disk... That just appears?

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Answers and clarifications will be much appreciated!

[Hodgkinson]

I had a odd issue back when I was using a 4MB add-on to my A1200 and I tried to boost the RAM a wee bit more with a 1MB PCMCIA SRAM card (Yes, I know its slllooow but emulation - PCx - Chews through ram). Despite tweaking the priority settings with MemPri the system totally ignored the SRAM RAM and decided to eat everything else, despite the SRAM definitely being present and adding to the total memory visible.

Maybe theres some limitation with regards to how or when SRAM can be used by the system as RAM:?

I know im posing more questions here, but I figured that they're relevant ;-)

Hodgkinson.

[smoorke]

1: I'm not sure as i havn't really experimented with SFS. But i guess you are correct in assuming filenames will get trucnated when copying from SFS to FFS
2: Size of ram disk is equal to it's contents plus a small filesystem overhead and adjusts dynamicly. Don't have any technical details on the operation of the reserving/releasing of memory but i know they are out there.
3: Ramdisk is automagicaly created upon first access. There are patches whom install diffrent handler and/or filesystem for the ram disk but with not having any first hand experience with them i can't tell you how they operate.

[Piru]

1) What filesystem does "Ram Disk" use, aka RAM:

Ram Disk has a custom filesystem. In fact, Ram Disk is the filesystem. It doesn't have a device at all. IIRC at least AmigaOS 1.x-3.x had filename/dirname length limit of 30 chars.

2) ) What size does "Ram Disk" have?
2: I assume that it grows dynamically? That it eats chunks of Ram, and frees RAM as it needs to store it's contents. And that it uses FAST RAM first, then Chip?

Ram Disk allocates memory in 1KB chunks, and it grows/shrinks dynamically. Memory type is MEMF_ANY, so highest priority memory is used first (fast > chip and so on).

3) How is "Ram Disk" created?

KS 2.0+: System initialization adds Ram Drive to the system automagically. First use of it starts the handler. The handler is located inside the kickstart ROM.

KS 1.x: ram-handler was on floppy disk (L:), and if it didn't exist accessing RAM: would fail.

[EDIT] Fixed my 1.x nonsense [/EDIT]

[Thomas]

there was a mountlist entry. Mount command had to be issued before the Ram Disk could be used. Regular Workbench (at least 1.3.x) startup-sequence did this.

That's not true. At least in 1.2 and 1.3 the same mechanism as in 2.0 was used. With the only difference that ram-handler was loaded from disk and if it was not there, the attempt to access RAM: failed. But you didn't need to mount it explicitely.

The same is true for SER: and PAR: and port-handler. And for PRT: and printer.device. Only OS4.0 introduced external mount files for SER, PAR and PRT.

Bye,
Thomas

[rkauer]

 Just confirming in reproduceable way:

 1- copy a file with long name (transfer it via Aexplorer, Dopus, or compressed in an archive). Put it directly on RAMDISK: ;

 2- See it via Workbench: the name will appear truncated;

 3- But in Dopus 4.18, the name appear just like the original, generated by a peecee with Win XP or other (better) OS. You can rename it to whatever you like.

[Piru]

@Thomas

Ah, true.

I think I mixed it with shell-seg or something. :-)

[SamOS39]

Ive never really understood what RAM disk is for..?

Maybe im missing something .. but what is the use of it?

[bloodline]

SamOS39 wrote:
Ive never really understood what RAM disk is for..?

Maybe im missing something .. but what is the use of it?

For temporary work... remember it was a time before Harddrives.

[krize]

I still like to use it for temp storage

[smerf]

Hi,

@Piru

You know for being so young you sure are one smart cookie,
I have been reading your posts lately, and if you are the
age as your picture depicts, you sure know a lot about the
Amiga. Don't let Thomas get your goat, by his picture he
was born before noah made the ark, so he should know a
little more than you.

smerf

[Piru]

@smerf

That picture is something like 23 years old :-)

[smerf]

Hi,

@Thomas

Hey, I was just going through some of my old Amiga disks and
found one named kickstart ram, I put it in my old 1000 and
it loaded it in to workbench, after I saw no difference, I
rebooted the 1000 by using the keyboard keys cntrl amiga amiga
the darn thing rebooted back into workbench, I didn't have
to put in my kickstart disk, tried rebooting back to
workbench again, shut off power than it disappeared.


smerf

[rkauer]

SamOS39 wrote:
Ive never really understood what RAM disk is for..?

Maybe im missing something .. but what is the use of it?

 RAM disk is used for other things than temporary storage:

 - definition of icons datatypes;
 - clipboard;
 - program definitions and libraries.

[davideo]

smerf wrote:
Hi,

@Thomas

Hey, I was just going through some of my old Amiga disks and
found one named kickstart ram, I put it in my old 1000 and
it loaded it in to workbench, after I saw no difference, I
rebooted the 1000 by using the keyboard keys cntrl amiga amiga
the darn thing rebooted back into workbench, I didn't have
to put in my kickstart disk, tried rebooting back to
workbench again, shut off power than it disappeared.


smerf

That's the other thing that Ram can be used for a RAD drive. This allows you to load anything into Ram and reboot your Amiga with it still there. You can do this with any Amiga - not just the A1000.

It was handy if you hadn't got a hard drive as you could do what you just did  :idea:

Dave G  8-)