Date: Mon, 11 Nov 1996 16:14:07 -0800 From: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> To: Karl Denninger <karl@Mcs.Net> Cc: andreas@klemm.gtn.com, acorreia@marlin.com.br, hackers@freebsd.org Subject: Re: Problems restoring Backups !!! Message-ID: <199611120014.QAA23601@freefall.freebsd.org> In-Reply-To: Your message of "Mon, 11 Nov 1996 17:45:17 CST." <199611112345.RAA10212@Jupiter.Mcs.Net>
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>Where can I find documentation on those AHC_* options, what they do, what >they might break, and when (or if) I should enable them? man 4 ahc >My problem with turning them on is that I've heard that some older disks >puke badly with them enabled. If your worried about data corruption (ie you don't have a server you can kick around to test this before deploying it), stay away from SCB paging. I think it works now, but it has not been tested by enough people yet. >On the other hand, I presume there are *serious* performance enhancements >available with them, specifically tagged-queueing. Tagged queueing offers a serios benefit and works just fine. The only reason it is an option (defaulting to off) is that some drives that say they can do tagged queuing can't. This is being remedied in the 'SCSI' branch by moving the tagged queueing stuff to the common layer and allowing quirk entries to be added for "losing" devices. SCB Paging is usefull because it allows more tags to be active at once. >-- >Karl Denninger (karl@MCS.Net)| MCSNet - The Finest Internet Connectivity >http://www.mcs.net/~karl | T1's from $600 monthly to FULL DS-3 Service > | 32 Analog Prefixes, 13 ISDN, Web servers $75/mo >Voice: [+1 312 803-MCS1 x219]| Email to "info@mcs.net" WWW: http://www.mcs.net >/ >Fax: [+1 312 248-9865] | 2 FULL DS-3 Internet links; 400Mbps B/W Interna >l -- Justin T. Gibbs =========================================== FreeBSD: Turning PCs into workstations ===========================================
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