On Sunday, 24 October 1999 at 8:53:28 -0700, Dennis Glatting wrote:
>
> I just want to document some strangeness I see with vinum, in case it
> has been noticed before but not identified, or someone knows a cure.
You should read vinum(4). It tells you what kind of information I
need for resolving problems. It also tells you to send the message to
me personally so that I don't miss them.
> I have a Dell XPS D333 with two Adaptec 2940 Ultra SCSI adapters, one
> assigned to fast things and the other to slow things, generally. On
> the slow adapter I have two SEAGATE ST43400N disks I placed under
> vinum. Below is my config file.
>
> drive a device /dev/da3e
> drive b device /dev/da4e
> volume vol1
> plex org striped 16k
This is too small. Choose 257 kB unless you have a good reason not
to. But it has nothing to do with your problem.
> sd length 2777m drive a
> sd length 2777m drive b
>
> When I run "iozone -aR" against the volume the entire disks subsystem
> seems to take a pause from time to time when the file sizes get large
> (>= 32 MB).
You don't really want to run iozone. Use rawio instead. But of
course you shouldn't get this behaviour.
> By this I mean the pause encompasses both disk controllers.
> Specifically, if I enter a command in a window, such as "ls,"
> against a disk on the fast controller and my cwd is on that
> controller too, then there is a big delay before the disk is listed,
> on the order of 5-10 seconds. My PATH variable does not include any
> devices on the slow controller. The window system still runs fine as
> does the network.
We seem to have buffer management problems in the kernel. I suspect
what you're seeing here is some kind of yo-yo effect where the system
uses up all its buffers and doesn't recover until a large number have
been flushed. I've added some additional checks to -CURRENT, but
they're not in -STABLE yet.
> FreeBSD 3.3-STABLE #23: Sat Sep 25 08:27:04 PDT 1999
This isn't really a question for -CURRENT then, is it? But since
you're here, try the same tests with -CURRENT and see if it happens
there too.
Greg
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