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From: Matthew Dillon <dillon@apollo.backplane.com>
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To: Mikhail Teterin <Mikhail.Teterin@murex.com>
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cc: freebsd-current@FreeBSD.org
cc: bde@zeta.org.au
Subject: Re: panic in ffs (Re: hangs in nbufkv)
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:[...]
:
:>    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.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>