[lug] writeable CD curiosity

David Anselmi anselmi at anselmi.us
Wed Feb 11 15:47:08 MST 2004

D. Stimits wrote:
> Another possibility that I wonder about only for curiosity, and not 
> necessarily for logging, is the concept of a RAID 1 where the partitions 
> being mirrored are (a) a ram-based filesystem and (b) a rewriteable CD 
> system...if power fails and ram is flushed, then the CD is used for 
> rebuilding the array; or while power runs, the CD could be ejected and 
> saved, a new CD added, and have it automatically rebuild the array via 
> copy from ram to CD-RW. What are the hardware limitations to this?

If you're going to write to the CD-RW as though it were a hard drive, 
why not use a hard drive?  What you describe seems to add nothing but 
poor performance and (relatively) short media life.

OTOH, if you log to a ramdisk it would be easy to hook cdrecord into 
your logrotate jobs so that current logs are kept on disk and old logs 
on CD.  Then use CD-R instead of CD-RW and they won't be erasable.

But do you really want to lose the most recent X minutes of logs when 
your machine crashes?

I think that what you want is a UDF filesystem.  There is some support 
for this in Linux, perhaps even more in the 2.6 kernel.  It probably 
doesn't work like you've described but it might be close enough.


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