Date: Tue, 06 Nov 2007 14:53:30 -0700 From: Scott Long <scottl@samsco.org> To: John Baldwin <jhb@freebsd.org> Cc: Dag-Erling Sm??rgrav <des@des.no>, freebsd-current@freebsd.org, Artem Kuchin <matrix@itlegion.ru>, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: BIO_FLUSH on twe driver. Why is it not there? Message-ID: <4730E25A.6030407@samsco.org> In-Reply-To: <200711061515.32551.jhb@freebsd.org> References: <0fbb01c81be1$37e698f0$0c00a8c0@Artem> <863avptzir.fsf@ds4.des.no> <20071102095506.GC24455@garage.freebsd.pl> <200711061515.32551.jhb@freebsd.org>
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John Baldwin wrote: > On Friday 02 November 2007 05:55:07 am Pawel Jakub Dawidek wrote: >> On Thu, Nov 01, 2007 at 10:41:00PM +0100, Dag-Erling Sm??rgrav wrote: >>> "Artem Kuchin" <matrix@itlegion.ru> writes: >>>> However, twe is working via scsi subsystem and the authour of gjournal >>>> said somewhere that he has had implemeneted BIO_FLISH for scsi and he >>>> specifically mentioned that he has tested twe and twa and they both >>>> support BIO_FLUSH. >>> twa(4) uses CAM, but twe(4) doesn't (and never has). >> That was my mistake. Someone told me (I think it was jhb@), that twe(4) >> turns off write cache automatically when there is no battery, so >> BIO_FLUSH isn't really needed and if there is a battery, it also isn't >> really needed. It would be nice to hide the warning in this case >> somehow, but for now you should be safe by simply ignoring the warning. > > I have no idea if twe(4) does this. I do know that both ciss(4) and mfi(4) > do this. Possibly amr(4) as well. > MFI can be overridden trivially, and so can AMR, so I don't consider them to be good examples. Scott
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