Soft updates and power failure

Pete French pete at twisted.org.uk
Tue Feb 8 12:10:06 GMT 2005


> You can disable caching on SCSI drives using camcontrol to alter the
> approrpiate modepage, though I cant remember which page it is.

Found it - modepage 8. Try the following (assuming yoir drive is da0)

	camcontrol modepage da0 -m 8

I get:

	IC:  0
	ABPF:  0
	CAP:  0
	DISC:  1
	SIZE:  0
	WCE:  0
	MF:  0
	RCD:  0
	Demand Retention Priority:  0
	Write Retention Priority:  0
	Disable Pre-fetch Transfer Length:  65535
	Minimum Pre-fetch:  0
	Maximum Pre-fetch:  0
	Maximum Pre-fetch Ceiling:  65535

But I bet yours has WCE set to 1.  If you add a -e to the end of that
line you can edit it and set it to 0 so that it is not doing any
write caching. That way when FreeBSD and Softupdates tell it to
write a block to the disc it will really write a block to the disc
so it will be consistent if the power goes.

-bat.




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