Date: Wed, 28 May 1997 17:37:28 -0600 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: Jaye Mathisen <mrcpu@cdsnet.net> Cc: scsi@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: More ahc0 driver problems. Message-ID: <199705282240.QAA02847@pluto.plutotech.com> In-Reply-To: Your message of "Wed, 28 May 1997 13:11:39 PDT." <Pine.NEB.3.95.970528130940.15391K-100000@mail.cdsnet.net>
next in thread | previous in thread | raw e-mail | index | archive | help
>Under bonnie to a ccd of sd2, sd3 (WD 4.1GB Enterprise drives): ... >Reams and reams of them. WHen it gets to the rewriting phase, it quiets >down. This problem has been mentioned many times before on this list. You are doing sufficient I/O local to one area of the drives that the drive is "starving" transactions that would require a long seek to complete for as long as 10 second. That's the reason the ordered tagged transaction (which basically means complete everything else before you run me) clears up the condition. Some changes coming down the line that turn synchronous writes into async, ordered writes will help to mitigate this problem as there will be an occasional ordered tagged transaction in the stream being sent to the driver. Of course, if you mount your filesystem async, this wouldn't happen. The Linux Buslogic driver works around this problem by simply sending an ordered tag "every once in a while". I don't really like that solution much. >How do I turn on write caching in my drive? I assume I have to edit some >mode page, but heck if I know which one. man 8 scsi. You should also look at /usr/share/misc/scsi_modes. -- Justin T. Gibbs =========================================== FreeBSD: Turning PCs into workstations ===========================================
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199705282240.QAA02847>