From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@9fans.net
Subject: Re: [9fans] Venti install trouble
From: "Russ Cox" <rsc@swtch.com>
Date: Mon, 19 May 2008 12:23:33 -0400
In-Reply-To: <20080516194257.GA7653@companion-cube>
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> The Venti has a data log of 1.4 TB across four arena partitions and 44GB
> in indexes across four index partitions. All the
> fmtarena/fmtisect/fmtindex commands suceeded without incident, but when I
> try to start the Venti for the first time, I get:
>
> venti: can't init server: illegal number of elements in /9/dev/sda2/isect
>
> What causes this error? Do I need more index space? Is there anything
> else I should try?

Venti imposes a limit of 2048 arenas in a venti system.
The constant is defined in /sys/src/cmd/venti/srv/dat.h
(or $PLAN9/src/cmd/venti/srv/dat.h) as MaxAMap:

	MaxAMap			= 2*1024,	/* max. allowed arenas in an address mapping; must be < 32*1024 */

If you recompile with this set to 30*1024, your system
will work just fine.

I am embarrassed to admit that I have no idea what
the purpose of this constant is (its only use is the check
that you are tripping over) or why it ``must be < 32*1024.''
I tripped over this a month ago setting up a 7 TB venti
and just bumped it to 30*1024 to get the system running.
I have been meaning to investigate further but haven't
had time.

Russ