Date: Thu, 29 Apr 1999 10:37:30 -0500 From: David Kelly <dkelly@hiwaay.net> To: freebsd-questions@freebsd.org Subject: Re: BSD Software RAID 0 and 1? Journaling file system? Message-ID: <199904291537.KAA53587@nospam.hiwaay.net> In-Reply-To: Message from Alfred Perlstein <bright@rush.net> of "Wed, 28 Apr 1999 22:38:03 CDT." <Pine.BSF.3.96.990428222303.10204k-100000@cygnus.rush.net>
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Alfred Perlstein writes: > On Thu, 29 Apr 1999, Greg Lehey wrote: > > You may have misunderstood the question. When a journaling/logging > > file system crashes, you don't need to run fsck: you replay the log. > > It makes up for the faster fsck by slower performance all the time. > > This is probably why nobody has been too concerned about it in the > > past. > > Er.... when you have a logging filesystem you can have an in place > log, since the superblock points to the last sucessful checkpoint > you just need to examine all partial segements after the last > sucessful checkpoint verifying thier completeness. > > I don't think you have to sacrifice speed at all as segments > written out can contain both metadata and data blocks, in fact > 4.4 BSD's LFS is superior at writing isn't it? I haven't measured it but having spent much of the last couple of years using Irix systems with XFS filesystems and FreeBSD, I believe both systems can do file I/O at about the same rate on identical HD's but XFS is much faster at metadata than even softupdates. Systems are an SGI O2 R5000 180 MHz with 64MB, FreeBSD 3.0 on a P-II 233 MHz with 64MB. Disks are identical Seagate 9G, ST19173W (if memory serves). A good example benchmark would be to extract the FreeBSD ports directory. Thousands of little files and directories. Another example would be "du -sk" on a directory with about 40,000 files. -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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