Date: Wed, 31 Mar 1999 17:03:46 +0200 From: HERBELOT Thierry <Thierry.Herbelot@alcatel.fr> To: bmcgover@cisco.com Cc: questions@FreeBSD.ORG Subject: Re: MFS Sizes over 470MB? Can't seem to do it... Message-ID: <37023952.28B139D7@telspace.alcatel.fr> References: <199903311310.IAA01959@bmcgover-pc.cisco.com>
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Indeed, MFS is related to the swap partition of the machine (just have a look at the mount command you used) The "general" rule for *BSD is to allocate a swap space at least twice as large as the real main memory (2 Gigs in your case). Then, you'll be able to use an MFS partition as large as 2 G (minus 10% ?). Anyway, even not using MFS, the integrated VM / buffer cache system of FreeBSD should give you almost all benefits of a RAM disk, as FreeBSD allocates unused pages of physical memory to disk caching. TfH Brian McGovern wrote: > > Recently, I purchased a system with 1GB of memory, the hope being to take > 768MB of it, and make it a MFS file system for doing buildworlds and releases > on. Currently, I set it up with (this is all on 3.1-RELEASE): > > mount_mfs -s <size> /dev/da0s1b /mountpoint > > I calculate "size" with: > > (1024 * 1024 * desired MBs) / 512 > > The 1024s are to define the number of bytes in a MB, then I multiply by the > number of MBs desired (im my case 768 would be nice), and then devide by 512, > the number of bytes in a sector... This should then give me the number of > sectors I need to pass to mount_mfs. > > Unfortunately, for increasing sizes of "desired MBs", there is a point at > approximately 470MBs where the MFS filesystem will no longer grow. > > Now, another odd number that approaches this is that I have 512MB of swap > on the machine. I hope I'm not stretching too far to think that 512MB - some > amount of overhead (10%-ish) would create a magic number somewhere near > 470.... > > Anyhow, my question is, are MFS file systems limited by swap space? If no, > is there any way to get a larger one configured. If yes, is it just a matter > of making sure there is sufficient swap space to back the size of the MFS? > -Brian > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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