(no subject)

Jerry McAllister jerrymc at msu.edu
Tue Dec 2 08:26:04 PST 2008

On Tue, Dec 02, 2008 at 10:56:44AM +0100, Pieter Donche wrote:

> If one has a system with 7 500Gb SATA disks in a hardware RAID6
> (Areca Raid Controller), then (according to mail J.Chadwick 7
> Nov 2008) they will show up as da (following naming convention
> for scsi disks although they are not).
> RAID6 will allow about 2,5 Tb for the 'user' (roughly 1 Tb will
> be consumed by the parity information of RAID6).
> How will this 2,5 Tb space present itself at the time of initial
> install of FreeBSD?
> Will this be a single 'disk'  ad0 ? .. correct or not (then what)?

It will start out looking like a single large disk /dev/da0.

> If FreeBSD is to put on the system as only operating system (Fdisk:
> "A = Use Entire disk"), then will the BSD-partitions will show up as
> ad0a (/), ad0b (swap), ad0d (/var) etc... correct or not (then what)?
> Page 427 of the FreeBSD handbook states that due to the use of 32-bit
> integers to store the number of sectors is limited to 2^32 -1 
> sectors/disk = 2 TB. A layout could be 
> a / 1Gb, 
> b swap, 
> d /root 20 Gb, (a /root partition is from an example of someone who
> claims that at boot FreeBSD checks the partions in background except
> for the / partition, by keeping / as small as possible, the time to
> boot can be mimimized .. correct? but will /root ever be something
> big ??)

No, it will not.    Do not make /root a separate partition/filesystem.
Leave it in /

> e /tmp 20 Gb, 
> f /var 20 Gb, 
> g /usr 20 Gb
> this leaves 2420 Gb which is more than 2 Tb, so you can't put all 
> that in 1 filesystem h /home, you will need to split that in 2
> BSD-paritions, but since you can't have more that 8 BSD-partitions
> (highest BSD-partition letter is h), you need to give up at least
> one of d, e, f, g. ... correct or not (then what)?

If you really need this much disk, there must be a reason.
What do you intend to put in it?     My suggestion would be to
put a lot more in /var because that is where data base utilities
default to putting their data.

Then you can reduce the amount left over to what would fit in /home.

    a:    1 GB    /
    b:    4 GB    swap
    d:    7 GB    /tmp
    e:   20 GB    /usr    ports can just be left here then
    f: 1024 GB    /var    databases live here
    g: remainder  /home   (Approximately 1536 GB)

You can shift this around as you need.   
Maybe 2048 GB /home and 512 GB /var


> What is the best scheme of BSD-partitioning in this case?
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