Jon Dama <[EMAIL PROTECTED]> writes: > softupdates is perfectly safe with SCSI. > > its well known that ide and sata w/wo ncq fails to provide suitable > semantics for softupdates > > however, journaling fairs no better, and request barriers do nothing to > solve the problem.
I had assumed that the sequence of operations in a journal would be idempotent. Is that a reasonable design criterion? [If it is, then it would make up for the fact that you can't build a reliable transaction gate. That is, you would just have to go back far enough that you *know* all of the needed journal is within the range you will replay. But even then, the journal would need to be on a separate medium, one that doesn't have the "lying to you about transaction completion" problem.] > On Thu, 14 Jul 2005, Matthias Buelow wrote: > > > Kevin Oberman wrote: > > > > >SCSI or ATA? If it's ATA, turn off write cache with (atacontrol(8) or > > >the sysctl. > > > > You do NOT want to do that. Not only will performance drop brutally > > (example: drop to 1/5th of normal write speed for sequential writes, > > probably worse for random writes) but it will also significantly > > reduce the lifetime of your disk. Modern disks are designed to be > > used with the write-back cache enabled, so don't turn it off. I have no idea what "designed to be used with the write-back cache enabled" could affect the operating life of the disk. _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
