Date: Tue, 12 Oct 2004 15:46:48 -0600 From: Scott Long <scottl@freebsd.org> To: Kris Kennaway <kris@obsecurity.org> Cc: bde@zeta.org.au Subject: Re: panic in ffs (Re: hangs in nbufkv) Message-ID: <416C50C8.9010903@freebsd.org> In-Reply-To: <20041012205105.GA76130@xor.obsecurity.org> References: <416AE7D7.3030502@murex.com> <200410112038.i9BKcCWt051290@apollo.backplane.com> <416C1B10.7030103@murex.com> <200410121818.i9CIIGRx092072@apollo.backplane.com> <20041012205105.GA76130@xor.obsecurity.org>
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Kris Kennaway wrote: > On Tue, Oct 12, 2004 at 11:18:16AM -0700, Matthew Dillon wrote: > >>:[...] >>: >>:> But to be absolutely safe, I would follow Bruce's original suggestion >>:> and increase BKVASIZE to 64K, for your particular system. >>:> >>:> >>:After doing this and testing our backup script, the machine panicked two >>:hours later (about half-way through the backup) with >>:"initiate_write_inodeblock_ufs2: already started" (in >>:ufs/ffs/ffs_softdep.c)... I guess, block sizes above 16Kb are just buggy >>:and newfs(8) should be honest about it... >>: >>: -mi >> >> Well, it's possible that UFS has bugs related to large block sizes. >> People have gotten bitten on and off over the years but usually it >> works ok if you leave the 8:1 blocksize:fragsize ratio intact. e.g. >> if you have a 64KB block size then you should use a 8K frag size. >> If you have a 32KB block size then you should use a 4K frag size. >> >> I think the buffer cache itself is is likely not the source of this >> particular bug. > > > FYI, I ran the package build cluster with 4:1 ratios for a few months > and did not have problems. If there are major bugs there I would have > expected to come across them. > > Kris IIRC, the fragment allocation code in FFS allocates in terms of bits withing a byte, so anything that is 8:1 or less should work. Scott
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