*BSD News Article 47746


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From: tls@cloud9.net (Thor Lancelot Simon)
Newsgroups: comp.unix.bsd.netbsd.misc
Subject: Re: NetBSD Filesystems
Date: 1 Aug 1995 09:25:01 GMT
Organization: Cloud 9 Internet, White Plains, New York, USA
Lines: 40
Message-ID: <3vkrtd$hn5@news.cloud9.net>
References: <1995Jul26.123455.28242@lssec.bt.co.uk> <3ve9jk$11b8@info4.rus.uni-stuttgart.de> <MICHAELV.95Jul30182230@MindBender.HeadCandy.com> <3vjcve$mah@wolfe.wimsey.com>
NNTP-Posting-Host: cloud9.net

In article <3vjcve$mah@wolfe.wimsey.com>,
Curt Sampson <curt@cynic.portal.ca> wrote:
>In article <MICHAELV.95Jul30182230@MindBender.HeadCandy.com>,
>Michael L. VanLoon <michaelv@MindBender.HeadCandy.com> wrote:
>
>>In article <3ve9jk$11b8@info4.rus.uni-stuttgart.de> ralf@informatik.uni-koblenz.de (Ralf Baechle) writes:
>>
>>   I found ext2fs MUCH faster due to it's
>>   asynchronous updates of the fs meta information for that case.
>>
>>This has nothing to do with the filesystem.  NetBSD (and I believe
>>FreeBSD) supports a flag that will let you mount the filesystem
>>asynchronously (wrt metadata writes).  However, it is not the default,
>>and most unix-seasoned people consider it just asking for trouble.
>
>It is asking for trouble. If you really need fast writes on lots
>of small files (i.e., for a news filesystem or something like that)
>the proper thing is to use the log filesystem or something similar.

Keep in mind that with many log-structured filesystems, the result on a 
crash may be that you lose the last bunch of files written outright, 
along with their metadata.  (Though since the files are lost, the lack
of metadata for them is of course correct. :-)  UFS is slightly more 
resistant to this, though obviously not completely.  If you're running a 
news server that _must_ be consistent with its active and history files, 
you really, really want a big UPS, no matter what filesystem you're using.

>Is LFS working in NetBSD?

Not really.  And unlike its Sprite cousin, it probably needs a version of 
fsck to really be stable across crashes/power events.  That program 
doesn't exist.

The only thing that seems to make it likely that LFS might get worked on 
enough to be useful is that I hear a rumor that the "ccd" striping device 
works on all the ports in -current.  LFS is a big, big win on RAID.
-- 
Thor Lancelot Simon                                               tls@cloud9.net

Somewhere they're meeting on a pinhead, calling you an angel.