On 04/01/2013 02:20 AM, Dan Egli wrote: > *Hey folks,* > > * * > > *Something that was mentioned a week or two back and I meant to follow up > but never did was changing cache mode for Linux's disk writes. How does one > accomplish that and can it be done on an individual drive basis? I.e. > Suppose I am using a set of hard disks in USB3 or eSATA enclosures to > backup my home system. If I backup the entire raid (i.e. dd if=/dev/md0 > of=/dev/md1) then how do I make sure that all the data was properly written > to the drives in md1 before I disconnect the drives and turn them off > (since they're in enclosures I can simply turn the enclosures off)? I don't > want to write that way, only to assume that everything is OK and find out > later that something didn't get written right. And yes, I know I could > simply do an individual file backup, and that's on the agenda too. But even > then, unless unmounting the md1 would force all cached data to be written > immediately anyway. But I am considering both options. So I would > appreciate it if someone could explain to me (since I've never tried > before) how you can go about disabling write caching to an individual drive. > * > > * * > > *Thanks!* > > *--- Dan* >
hdparm -W will let you read and set the drive's write-cache enable flag (assuming the drive actually obeys it, I've heard rumor some don't). As I recall, you will need to turn off the write-cache each time you boot. Grazie, ;-Daniel Fussell /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
