Date: Sun, 20 Nov 2005 13:59:14 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Peter Jeremy <PeterJeremy@optushome.com.au> Cc: freebsd-current@freebsd.org, Anderson <anderson@centtech.com>, Eric, Brian Candler <B.Candler@pobox.com> Subject: Re: Logical volume management Message-ID: <20051120135914.5ac63e2d@Magellan.Leidinger.net> In-Reply-To: <20051119050216.GU39882@cirb503493.alcatel.com.au> References: <20051118114308.GA11281@uk.tiscali.com> <437DCB6D.6090400@centtech.com> <20051118125922.GA11684@uk.tiscali.com> <20051119050216.GU39882@cirb503493.alcatel.com.au>
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On Sat, 19 Nov 2005 16:02:16 +1100
Peter Jeremy <PeterJeremy@optushome.com.au> wrote:
> The other disadvantages I see are:
> - All the cylinder groups headers are pre-allocated. AFAIK, UFS2 avoids
> pre-allocating the inodes but still reserves the space for them. A
> large virtual filesystem will have significant overheads even if it
> only has a small amount of real data.
> - UFS assumes that all the space is physically available and allocates
> blocks so as to (hopefully) maximize performance. This is likely to
> lead to significant fragmentation with lots of partially utilised
> data chunks.
I think those are the reasons why Sun decided to integrate the "new" VM
and the new FS code into one black box called ZFS (to prevent someone
from using a plain UFS with the new VM and then moan because of the
non-optimal performance).
Bye,
Alexander.
--
Speak softly and carry a cellular phone.
http://www.Leidinger.net Alexander @ Leidinger.net
GPG fingerprint = C518 BC70 E67F 143F BE91 3365 79E2 9C60 B006 3FE7
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