[mythtv-users] How does the diskless setup work?

Michael Carland mcarland at bitsgonewild.net
Wed Jun 8 00:05:09 UTC 2005


On Jun 7, 2005, at 3:30 PM, Egeekial wrote:

> I realized that was somewhat redundant. I forgot to throw in putting 
> the whole OS on the CF card read-only instead of booting off the 
> network.
>
> Egeekial wrote:
>
>> Has anyone tried using a compactflash card for a drive? They make 
>> IDE->Compactflash converters. This wouldn't exactly be "diskless", 
>> but it would be "hard drive-less".
>>
>>> On 6/7/05, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>>>
>>>> Michael Carland wrote:
>>>>
>>>>
>>>>> One idea if PXE doesn't work, or you don't have PXE, and you still
>>>>> want a silent machine, would be to boot from flash (or even 
>>>>> floppy). I
>>>>> have a CompactFlash to IDE adapter, that can be used to load a 
>>>>> kernel,
>>>>> and the rest could be loaded from network. If the motherboard 
>>>>> supports
>>>>> booting from a USB drive, this would do the same thing. You could 
>>>>> even
>>>>> load the kernel from a floppy, although when I used to do this the
>>>>> same floppy sitting in the same drive for months on end would need 
>>>>> to
>>>>> be replaced once or twice a year. Not exactly diskless in that 
>>>>> case,
>>>>> but other than 30 seconds at boot, there is no drive noise.

If the compact flash is large enough, you have a few options.

1) As already mentioned, just put the kernel on the CF. Once kernel is 
loaded, all disk is NFS.
2) Put the kernel and an initrd image on the flash. The kernel would 
load the image into a ramdisk, and the flash would not be used after 
that. What was not in flash would be mounted from NFS, if anything.
3) Same as 2, except there is an additional filesystem on the flash, 
that is mounted from the flash. So / , /dev , /var would be in  the ram 
disk, and /usr and such would be mounted from the CF. An advantage to 
this would be that would would save RAM by not loading all of /usr into 
memory. You don't want to mount directories such as /var on the CF, CF 
can only handle a certain number or writes (10s of thousands?) before 
it fails, and the constant writing of logs and such can quickly wear 
out the flash. It's not relevant for /usr, since it would be mounted 
RO.

-Michael



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