Date: Sun, 01 Feb 1998 13:45:58 -0600 From: mikk0022@maroon.tc.umn.edu To: Terry Lambert <tlambert@primenet.com> Cc: Matthew.Alton@anheuser-busch.com, fs@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: Filesystem hacking Message-ID: <199802011945.NAA18654@x115-105.reshalls.umn.edu> In-Reply-To: Your message of "Sun, 01 Feb 1998 00:49:17 GMT." <199802010049.RAA18732@usr06.primenet.com> References: <199802010049.RAA18732@usr06.primenet.com>
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On Sun, 1 Feb 1998 00:49:17 +0000 (GMT) Terry Lambert wrote >> What do you know about LFS for FreeBSD. I haven't used >> it, but from what I understand, it was an early implementation >> of a "log-structured filesystem" for BSD. Are "log-structured" >> and "journaling" synonymous? > >No, they are not. A log-structured FS logs data; a journalling >FS logs data and transactions in a transaction journal. > >A log structured FS can only roll transactions back to recover from >failures. A journalling FS can roll transactions forward. OK, let's see if I get this -- a log-structured filesystem stores file data and metadata only in its log. A journaling filesystem stores data, metadata, *and operations* in the log? >A Journalling FS also allows you to expose a transactioning interface >to allow you to group transactions. Is there a portable way to do this? >XFS internally seems to look a lot like NTFS internally. That is, >it seems to journal. I've only looked at images of small XFS's >snapshotted before and after transactions, I haven't really >snooped out the structure. You probably know more about both than I do. All I know about XFS is what I read in the "white paper" on SGI's web site... >> As far as Logical Volume Management, SGI's XLV is a good target >> (can you tell what kind of UNIXen I use at work yet? :-). In my >> understanding, the system marks each disk with its place in the >> volume, so the logical volume can be automagically composed on >> boot-up. This is nice, because there is no configuration file to >> worry about, and you can move around the disks on the >> SCSI chain without affecting the volume. > >CCD can do this as well. How? I thought CCD built the logical volumes from /etc/ccd.conf on bootup. Thus, moving around disks would require editing /etc/ccd.conf on bootup. XLV does this all automatically. Or has this been added in -current ? -- Chris Mikkelson mikk0022@maroon.tc.umn.edu Microsoft: We're the software company -- we don't care, 'cause we don't have to. --- Lily Tomlin, updated
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