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MFS_DEVICE and Mormon marriages

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Posted by: HTH

In the thread Blessing original MFS partition, there were these bits of information:

quote:
Originally posted by Tiger:
momstart (What I believe handles locking and MFS access in general) is hardcoded to use the /dev/hda10-/dev/hda11 pair and the /dev/hdb2-/dev/hdb3 pair. No way to add a third.


quote:
Originally posted by cramer:
Wrong. "momstart" is not hardcoded; it looks for an environment variable (MFS_DEVICE) to tell it where to find a volume set (pair of partitions.) You can point it to any pair of partitions that are part of a valid MFS volume. Each "application region" partition holds something like a superblock or signature pointing out the structure of the entire MFS filesystem.

While I've not figured out how to get FsVolume::AddDisk() to extend more than once, MFS can be composed of many more than two pairs -- I've gone as high as six before I got bored and stopped.


quote:
Originally posted by cc:
You can't [extend more than once]. However, you can add more than 1 pair of disks the first time. But once you perform a blessing, you can't extend MFS any further.

So instead of trying to get a 3 pair MFS volume by starting with one, adding one, then attempting to add another one, do it by starting with one, and then adding 2 pair all at once.


quote:
Originally posted by IronHelix:
Has anyone tried this [to make a 160 GB TiVo]? Successfully? Unsuccessfully?


quote:
Originally posted by pschum:
[A]bove there is talk about MFS_DEVICE having something to do with multiple MFS partitions. I blessed a drive and allowed the marriage to occur, but the value in MFS_DEVICE never changed from '/dev/hda10'. What am I missing here?

Tiger says 'momstart' and cramer says 'FsVolume::AddDisk()' (this is a method in which program???), but it appears that mfsadd is responsible for performing the marriage, and it IS hard-coded to hdb2 and hdb3. I'm confused.


It appears that, while it is hard coded for those, it won't use them if MFS_DEVICE defines something else. It is typical for applications to have some values hard-coded but allow them to be overridden by environment variables. For example, the tin newsreader could be compiled to use a specific news server, but could be overridden with the NNTPSERVER environment variable.

I'd really like to try this out. I have two 30hr TiVos with 45 GB brides to be married to 60 GB grooms. I'd like to make use of the remaining 15 GB of the brides. I originally thought I'd just make them extra /hack space, but other ideas like imaging an active 14hr partition in there or performing this Mormon marriage (reverse-Mormon?) have me intrigued.

But so far we seem to be short on some details. I'm assuming that MFS_DEVICE would have to be defined before marriage to point to the new partitions via the shell rather than just installing the drives and hoping it finds everything and running, what, mfsadd? How does one appropriately define MFS_DEVICE?

Yes, I could have bumped the thread, but there wasn't much response to the last bump it received and with this more-descriptive subject it should gain more attention. Let's make some 163.3 GB (152.1 GiB) TiVos! By the estimation of 1.28 Basic-hrs/additional-GB, that would be somewhere from 196 to 201 hrs at Basic.

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http://www.war-of-the-worlds.org/tivo/HTH.gif

[This message has been edited by HTH (edited 12-18-2000).]


Posted by: Tiger

I believe all MFS_DEVICE does is tell it where to look for the first partition (/dev/hda10) The first partition then has the device names for all partitions involved in the MFS set. So I'm not sure I agree with all the above messages.

Also, in mine I said momstart, I meant mfsadd.. Though it could also be in libmfs or libmom.

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TMNBT Special Forces
Are we not men? We are TiVo!


Posted by: cramer

quote:
Originally posted by Tiger:
I believe all MFS_DEVICE does is tell it where to look for the first partition (/dev/hda10)


Correct. That's basically "where MFS is." It does appear to have to be the first application region, tho' it may also work for the second application region in cases where MFS was initialized with two sets. (And YES I can extend those creatures as well now. So you two drive TiVo owners, your salvation is at hand -- ok, so it'll be a bit messy as I cannot provide a new copy of mfsadd [that's tivo's property] but I can give you instruction on what to do to the v1.3.0 mfsadd to make the new mfsadd. http://www.avsforum.com/ubbtivo/biggrin.gif)

quote:

The first partition then has the device names for all partitions involved in the MFS set. So I'm not sure I agree with all the above messages.


Technically, all the application regions hold a complete list. TiVo obviously isn't going to tell us anything at all, so we're left guessing why.

quote:

Also, in mine I said momstart, I meant mfsadd.. Though it could also be in libmfs or libmom.



Yes, mfsadd is hardcoded. You can see the devices with 'strings':


HOWEVER the extension is added to MFS_DEVICE despite these checks as that's how libmfs works. I can provide a detailed description of what mfsadd does if there's interest. (No, this won't reveal any secrets of MFS. Sorry.)



Posted by: pschum

quote:
Originally posted by cramer:

Yes, mfsadd is hardcoded. You can see the devices with 'strings':


HOWEVER the extension is added to MFS_DEVICE despite these checks as that's how libmfs works. I can provide a detailed description of what mfsadd does if there's interest. (No, this won't reveal any secrets of MFS. Sorry.)


I "hacked" a copy of mfsadd to look for a different volume pair and I was successful (the marriage worked but it's the "traditional" kind -- no Mormons!), but that seems to be the difficult way to do what Tiger has already done with a one-disk expansion. So I, for one, would be interested in your detailed description of mfsadd.

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Paul Schumann
"Share and Enjoy"


Posted by: janedoe4997

quote:
Originally posted by HTH:
...I'd really like to try this out. I have two 30hr TiVos with 45 GB brides to be married to 60 GB grooms. I'd like to make use of the remaining 15 GB of the brides.


My 45gb bride and 60gb groom are in the same 'family-way' and I look forward to their new arrival (of an extra 15gb).

To: Tiger, pschum, Bill Parker and others...

Why couldn't we just use the pdisk command on our Tivo's to wipe out partitions 10 and 11, and recreate
them larger in size (up to the full remaining size of our drive A's)???

I believe I read that the system checks the size of p10 and
p11 upon booting, and uses those numbers, so why should it care if we enlarged those partitions, and then rebooted?



[This message has been edited by janedoe4997 (edited 12-18-2000).]


Posted by: MikeLaw

Add me to the list of people who be very interested in the details of the mfsadd operation.

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....mike


Posted by: Tiger

The reason is that partition 10 is has the size of partition 11 in it, with allocation tables only so large. Creating a bigger partition doesn't do any good.

And cramer, the first block, where the list of partitions would be, is blank on my mfsadded drive. It may not be the case for factory dual drives, but for mfsadd it is.

------------------
TMNBT Special Forces
Are we not men? We are TiVo!




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