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Date: Sat, 3 Dec 2011 13:31:07 GMT
From: Eugen Konkov <kes-kes@yandex.ru>
To: freebsd-gnats-submit@FreeBSD.org
Subject: can not connect through ssh to server when /usr is 100% busy
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>Number:         163038
>Category:       misc
>Synopsis:       can not connect through ssh to server when /usr is 100% busy
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Dec 03 13:40:03 UTC 2011
>Closed-Date:    Fri Dec 09 12:40:12 UTC 2011
>Last-Modified:  Mon Dec 26 08:00:22 UTC 2011
>Originator:     Eugen Konkov
>Release:        9
>Organization:
ISP FreeLine
>Environment:
FreeBSD flux 9.0-CURRENT FreeBSD 9.0-CURRENT #4: Fri Jun 10 01:30:12 UTC 2011     :/usr/obj/usr/src/sys/PAE_KES  i386

>Description:
when hard drive is 100% busy and I/O operations on /usr slice
you can not connect to system until IO complete

dump -0L -f - /usr | gzip -2 | ssh -c blowfish u@u dd of=/usr/sharedzone/snap/dump-usr.gz

df -h
/dev/ad0s1f    1.8T     21G    1.6T     1%    /usr

It seems that dump lock slice while doing snapshot

tty also locked if I try to 'cd to /usr/.snap'
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: jh 
State-Changed-When: Fri Dec 9 12:38:52 UTC 2011 
State-Changed-Why:  
Unfortunately not much can be done to fix this. FFS snapshots require 
suspending all file system operations during the snapshot creation. 
Snapshot creation can take considerable long time on large file systems. 

ZFS offers quick snapshotting. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=163038 

From: KES <kes-kes@yandex.ua>
To: bug-followup@freebsd.org,kes-kes@yandex.ru
Cc:  
Subject: Re: misc/163038: can not connect through ssh to server when /usr is 100% busy
Date: Mon, 26 Dec 2011 10:00:00 +0200

 I am agree that you lock write operations, but why do you lock read operations too?
>Unformatted:
