Date: Sat, 6 Jul 2002 16:42:22 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Bernd Walter <ticso@cicely5.cicely.de> Cc: Terry Lambert <tlambert2@mindspring.com>, Darren Pilgrim <dmp@pantherdragon.org>, ticso@cicely.de, freebsd-hackers@FreeBSD.ORG Subject: Re: How does swap work address spacewise? Message-ID: <200207062342.g66NgMri063859@apollo.backplane.com> References: <20020705113532.GA11273@atrbg11.informatik.tu-muenchen.de> <20020705133515.GA295@HAL9000.wox.org> <20020705133837.GA513@HAL9000.wox.org> <20020705234126.GA12183@atrbg11.informatik.tu-muenchen.de> <3D2640A7.3EA2236B@pantherdragon.org> <20020706020656.GL48977@cicely5.cicely.de> <3D2762FE.9D9E0378@pantherdragon.org> <20020706220720.GG23704@cicely5.cicely.de> <3D277274.B5F3CE58@pantherdragon.org> <3D2776BE.A39A1110@mindspring.com> <20020706231346.GJ23704@cicely5.cicely.de>
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Negative block numbers are used by UFS to represent the indirect blocks
associated with a file, while positive block numbers represent the
contents of the file.
These are logical block numbers, which are fragment-sized (1K typically).
So, 2^31 x 1K = 2TB.
Physical block numbers are 512-byte sized, with a range of 2^32
in -stable. This also winds up being 2TB. So increasing the fragment
size does not help in -stable.
In -current physical block numbers are now 64 bits, removing the 2TB
limit, and UFS2 uses 64 bit block numbers, removing the filesystem-imposed
2TB limit. I'm not sure how much more work there is to go in this
area, you could ask Poul or Kirk.
-Matt
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