Date: Thu, 01 Feb 2001 17:44:04 -0800 From: Randy Primeaux <randy@Cloudfactory.ORG> To: Tony Landells <ahl@austclear.com.au> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: installing onto vinum Message-ID: <200102020228.SAA04507@relay.ultimanet.com> In-Reply-To: Message from Tony Landells <ahl@austclear.com.au> of "Fri, 02 Feb 2001 09:38:52 %2B1100." <200102012238.JAA00291@tungsten.austclear.com.au>
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Tony,
It will be several hours before I can resume testing. In the
meantime, I have a question.
Per `man 8 vinum`:
vinum uses the first 265 sectors on each partition for configuration in-
formation, so the maximum size of a subdisk is 265 sectors smaller than
the drive.
My new interpretation is that I should reserve 265 sectors per subdisk
for configuration information. Following method one, where each
subdisk overlays a partition, I might choose to layout /var, /usr, and
/home initially 265s larger, then shrink each of them.
Part of my confusion stems from the fact that Greg's example provided
for two subdisks, and I chose to test with three.
Greg's example:
>
> 6. Carefully calculate the offsets and the lengths of the file
> systems. Create a Vinum configuration file something like this:
>
> drive root dev /dev/ad0s1d
> volume usr
> plex org concat
> sd length 256m
> volume home
> plex org concat
> sd length 8g driveoffset 524553s
>
> The lengths and offsets need to be exact, of course. The best way
> to get offset and length is from the last 8 lines of disklabel
> ouput.
My first interpretation for three subdisks:
>
> drive root dev /dev/ad4s1d
> volume var
> plex org concat
> sd length 256m driveoffset 265s
> volume usr
> plex org concat
> sd length 4g driveoffset 1048841s
> volume home
> plex org concat
> sd length 79574302s driveoffset 8913161s
So on to my query. Using this example, should my second vinum subdisk
actually be 8388608s - 265s = 8388343s, where the original 4.2BSD
partition was 8388608s, thereby reserving 265s per each subdisk?
If not, then why?
At this point, when I resume testing, I'll need to modify /vinum.cfg
and replace keyword `dev` with `device`, then try again.
BTW, I just read Greg's recent response, so I am taking that into
consideration as well. Thank you for the response. A few comments
follow, below.
Tony Landells writes:
> Hi Randy,
>
> Let's see if I can give Greg a break (having just been through this)...
>
> > It's not clear to me how to properly calculate the sector offset and
> > sizes, as I do not have a clear example to follow. Does the vinum
> > partition overlay all of the original var usr and home plus the last
> > 265 sectors of swap?
>
> Yes.
>
> Basically there are two ways to use your disk space with vinum. The
> first, not so good way, is to do all your partitioning, and then define
> each partition as a vinum drive. I assume this would then require 265
> sectors for vinums configuration data on each partition, which is pretty
> wasteful.
>
> The second method is just to give vinum a big slab of disk space, and
> then slice it up within vinum. This means that there is only one set
> of vinum configuration (for that space). The other advantage is that
> you can make more slices on a large disk because vinum isn't limited
> to the a through h stuff.
>
> Since sysinstall doesn't understand vinum, Greg's "cheat" does all the
> installs on "standard" slices, and then sets up the vinum configuration
> to match. But since vinum can only allocate space it controls, the
> vinum slice you create with disklabel needs to overlap the other slices
> you want to configure under vinum.
>
> So onto the specifics of what you've done...
>
> > I start out with the following disklabel:
> >
> > 8 partitions:
> > # size offset fstype [fsize bsize bps/cpg]
> > a: 524288 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 32*)
> > b: 1048841 524288 swap # (Cyl. 32*- 97*)
> > c: 90060327 0 unused 0 0 # (Cyl. 0 - 5605*)
> > e: 524288 1573129 4.2BSD 1024 8192 16 # (Cyl. 97*- 130*)
> > f: 8388608 2097417 4.2BSD 1024 8192 16 # (Cyl. 130*- 652*)
> > g: 79574302 10486025 4.2BSD 1024 8192 16 # (Cyl. 652*- 5605*)
> >
> >
> > This is a test layout, in which I want / and swap to be static, and
> > /var, /usr, /home to be on vinum, to be mirrored on ad5 when I am
> > done.
> >
> > My intended layout is as such:
> > ad4s1a / 256M
> > ad4s1b swap 1048841
> > ad4s1e /var 256M
> > ad4s1f /usr 4G
> > ad4s1g /home 79574302
>
> Well, this is actually the way you allocated it originally (you haven't
> taken the vinum space out of swap here), but I know what you meant. (I
> only mention it for others following the example.)
Yes, this example would be clearer if I showed this "Before" table,
and an "After" table.
> > I booted a release CD, then operated the fixit floppy so I had vi
> > available without mounting /usr. I then changed the disklabel as follows.
>
> A safe way to go, though I found that you can do pretty much everything
> in single user mode after executing "mount -a". Really.
Ok, Tony, I'll try that. I feared hitting this error again, based
upon a mis-interpretation on my part:
disklabel: ioctl DIOCWDINFO: open partition would move or shrink
As an aside, I had commented out partitions e, f, and g on my first
attempt. On my second attempt I left them intact, and added d:.
> > 8 partitions:
> > # size offset fstype [fsize bsize bps/cpg]
> > a: 524288 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 32*)
> > b: 1048576 524288 swap # (Cyl. 32*- 97*)
> > c: 90060327 0 unused 0 0 # (Cyl. 0 - 5605*)
> > d: 88487463 1572864 vinum # (Cyl. 97*- 5605*)
> > e: 524288 1573129 4.2BSD 1024 8192 16 # (Cyl. 97*- 130*)
> > f: 8388608 2097417 4.2BSD 1024 8192 16 # (Cyl. 130*- 652*)
> > g: 79574302 10486025 4.2BSD 1024 8192 16 # (Cyl. 652*- 5605*)
>
> So far so good. I assume you confirmed that this was the label on the disk?
>
> > I modified /etc/fstab following your example above, with
> > /dev/vinum/var added.
> >
> > I then ran `vinum create vinum.cfg`
> > I got:
> >
> > vinum: loaded
> > 3: drive root dev /dev/ad4s1d
> > **3 Drive root, invalid keyword: dev: Invalid argument
> >
> >
> > vinum.cfg:
> > drive root dev /dev/ad4s1d
> > volume var
> > plex org concat
> > sd length 256m driveoffset 265s
> > volume usr
> > plex org concat
> > sd length 4g driveoffset 1048841s
> > volume home
> > plex org concat
> > sd length 79574302s driveoffset 8913161s
> >
> >
> > does "drive root dev /dev/ad0s1d" need to be `device` ?
>
> Yes.
>
> Some other comments... Given that you specified all the sizes in
> "user friendly" form when you did the initial slicing, I tend to
> use the (final) disklabel as the basis for my vinum config and specify
> all the lengths in sectors. It's really just paranoia, so from:
>
> 8 partitions:
> # size offset fstype [fsize bsize bps/cpg]
> a: 524288 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 32*)
> b: 1048576 524288 swap # (Cyl. 32*- 97*)
> c: 90060327 0 unused 0 0 # (Cyl. 0 - 5605*)
> d: 88487463 1572864 vinum # (Cyl. 97*- 5605*)
> e: 524288 1573129 4.2BSD 1024 8192 16 # (Cyl. 97*- 130*)
> f: 8388608 2097417 4.2BSD 1024 8192 16 # (Cyl. 130*- 652*)
> g: 79574302 10486025 4.2BSD 1024 8192 16 # (Cyl. 652*- 5605*)
>
> I'd have:
>
> drive root device /dev/ad0s1d
>
> volume var
> plex org concat
> sd length 524288s
> volume usr
> plex org concat
> sd length 8388608s
> volume home
> plex org concat
> sd length 79574302s
>
> The "driveoffset 265s" for the first sub-disk is the default, and for
> all the following sub-disks the space is allocated sequentially, so
> unless there is an error creating one of the sub-disks, things will
> be allocated correctly. Since home extends to the end of the partition
> you could specify the length as "0" (zero).
>
> A couple of other points:
>
> 1. If you mess up after you've started doing the vinum stuff
> and want to start again, I've found that occasionally vinum
> gets confused by old data on the disk. If you're starting
> again (including the fdisk and disklabel stuff), you may
> also want to nuke any old vinum information after you've
> finished the disklabel setup with
>
> "dd if=/dev/zero of=/dev/ad0s1d count=265"
>
> 2. When you create and attach the second plex for a mirror
> (assuming that's where you're going), it (and its sub-disks)
> will come up as (apparently) faulty. This only indicates that
> it doesn't have current data on and can't be used. Once you
> "start" the sub-disks they will copy the data from the first
> plex, and when that's finished the plex will come up.
>
> Hang in there, it gets easier!
>
> Tony
> --
> Tony Landells <ahl@austclear.com.au>
> Senior Network Engineer Ph: +61 3 9677 9319
> Australian Clearing Services Pty Ltd Fax: +61 3 9677 9355
> Level 4, Rialto North Tower
> 525 Collins Street
> Melbourne VIC 3000
> Australia
>
--
Randy Primeaux
randy@cloudfactory.org http://cloudfactory.org/~randy/
tranze@hyperreal.org http://hyperreal.org/~tranze/
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