Date: Thu, 16 May 1996 14:38:43 -0500 (CDT) From: Bob Willcox <bob@luke.pmr.com> To: jgreco@brasil.moneng.mei.com (Joe Greco) Cc: joerg_wunsch@uriah.heep.sax.de, kelly@fsl.noaa.gov, taob@io.org, jgreco@brasil.moneng.mei.com, freebsd-chat@freebsd.org, asami@cs.berkeley.edu Subject: Re: 3 terabytes on one server? (was Re: more than 32 scsi disks on a single machine ?) Message-ID: <199605161938.OAA10398@luke.pmr.com> In-Reply-To: <199605142258.RAA11250@brasil.moneng.mei.com> from Joe Greco at "May 14, 96 05:58:04 pm"
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Joe Greco wrote: > > As Sean Kelly wrote: > > > > > Yep. The sixth field is the fsck pass number. fsck runs in order of > > > pass number, entries with the same number are run in parallel. > > > > Only two distinct pass numbers are supported, however. The first is > > for the root f/s, the other one for the rest. > > Really?!?! That's a little alarming, for those of us who put multiple fs's > on the same disk... > > The Sun implementation allows me to do > > /dev/sd0a / 4.2 rw 1 1 > /dev/sd0b swap swap rw 0 0 > /dev/sd0g /usr 4.2 rw 1 2 > /dev/sd2b swap swap rw 0 0 > /dev/sd2g /usr/local 4.2 rw 1 2 > /dev/sd4d /var 4.2 rw 1 5 > /dev/sd3a /var/spool 4.2 quota,rw 1 3 > /dev/sd4a /tmp 4.2 quota,rw 1 4 > /dev/sd4b swap swap rw 0 0 > /dev/sd4f /usr/u1 4.2 rw 1 3 > /dev/sd4g /nfs 4.2 rw 1 2 > /dev/sd6a /usr/u0 4.2 quota,rw 1 2 > > Notice all the partitions on sd4, a heavily beat upon 660MB disk... I > set those up to fsck in order (note the pass #'s)... > > Now admittedly FreeBSD's fsck is a lot faster :-), but if this really is a > limitation, it is too bad.. maybe I will go look at it :-) I believe you don't understand the way FreeBSD actually handles this. (Heck, maybe I don't either, but this is what I actually observe happenning.) After fscking / (with a pass number of 1), it then fsck's all the other filesystems (with pass numbers of 2) by forking a process for each disk. These per-disk processes fsck their file systems in sequence. I have observed this behavior numerious times on my file server with 14 disks and 3 SCSI busses (with disks on them, I have a 4th with a CDROM drive & a couple of Exabyte tape drives that doesn't get to participate in the fun :-). It is *very* apparent that all 14 disks are being fscked at the same time. -- Bob Willcox bob@luke.pmr.com Austin, TX
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