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Date: Wed, 30 Jun 1999 20:54:30 +0400 (MSD)
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Subject: kern/12466: Fast system hangs under high FS load
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>Number:         12466
>Category:       kern
>Synopsis:       Fast system hangs under high FS load
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jun 30 10:00:01 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator:     Dmitry Flitmann
>Release:        FreeBSD 3.2-STABLE i386
>Organization:
National Electronic Library, Moscow, Russia
>Environment:

Intel Sc450NX, 2xXeon 500Mhz/512K cache, 1G RAM, SymBios/NCR 53c896 u2w SCSI
(also tried Adaptec 2940U2W), 3xSEAGATE ST318203LC (Cheetah) disks.

OS: FreeBSD 3.2-RELEASE, 3.2-STABLE, 4.0-CURRENT
(3.2 - with "Current" NCR driver)
either in SMP mode or not.

>Description:

System hangs while copying a large tree of small files between
two disks (~150Mb, 200'000 files).
No diagnostic is given.
No new processes can be created, already running ones - continue running 
until any disk operation attempt.

We tried different SCSI controllers (symbios 53c896 & adaptec 2940U2W),
different kernels (RELEASE/Current/Stable, with or without SMP).

ktrace shows last operation - "namei" while opening file for reading.

When we launch some serious background job, everything seems to work fine
(slower, of course).

We think it is a filesystem  problem with locking/delays/etc, which appears
only on a fast systems.

>How-To-Repeat:

Try copying a large tree of small files from one disk to another
on an idle system
(cp -RPp /ar/archive /ar1/ )

>Fix:
	
workaround - to slow down system by running a large background job.

>Release-Note:
>Audit-Trail:
>Unformatted:


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