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Old 17th August 2010
IronForge IronForge is offline
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Default Partitioning the LiveUSB drives.

Greetings, Gents:

Hope all is well. It's been awhile, so pardon the lack of retained knowlege here. I've been looking into making a LiveUSB myself (I'm running into USB drive only machines in some public places). I was contemplating a 4GB or 8GB Drive with 1GB partitioned as FAT32 (for M$ Machines) - which makes 3GB or 7GB available. I've been reviewing the documents; and have the following questions:

The FAQ Chapt 14 mentioned a few pointers regarding partitioning /swap and /var to accomodate the Machine's RAM (for core dumps). Am I correct in presuming (since the Live USB section didn't mention) that following the /swap and /var size guidelines are impractical? If so, are there any guidelines or precautions (read the minimal and most practical partition sizes) one should consider for sizing /swap and /var on LiveUSB installs? I once tried an install using the "Automated" partitioning option; and IIRC, it left a good portion of the drive unused.

If I go by the "/swap and /var = RAM of Machine most Accessed", I get
/ 250MB
/swap 2GB
/tmp 50MB
/var 2GB
/usr 2.7GB-ish
...with 1GB as FAT32

Doesn't look right - as in "Even if I do a backup of portable files from snapshot to snapshot, I don't think I can do a good number of pkg_adds and updates this way. I remember having a discussion on partitions; but can't recall it all.

Pls advise, thanks.

BTW, Congratulations, Ocicat!!!
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Old 17th August 2010
ocicat ocicat is offline
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Quote:
Originally Posted by IronForge View Post
Am I correct in presuming (since the Live USB section didn't mention) that following the /swap and /var size guidelines are impractical?
It is very easy to obsess & argue about partition sizing. The purpose of partitioning is to place an upper limit on runaway processes which might fill up the disk. By confining a process to a limited amount of the disk, it might fill up the partition, but hopefully not take the system down with it. Note that partitioning is not the same thing accomplished by chroot(8).

Note also that this is a classic interpretation of partitions -- running on a system which conceivably may be up for months at a time with a number of users connected running an unforeseen number of applications of even greater unforeseen quality.

Given that you are wanting to construct a USB system which may be up for only hours instead of months, you have more latitude in how the system "should" be partitioned, if it needs to be partitioned at all. After all, you are most likely going to be the only user.

jggimi will state that partitioning (especially for transient systems) may be unnecessary at all. Outside of swap, create one large "a" partition, & be done with it. You are already questioning the confinement provided by partitioning; with only one partition, growth is more fluid & not as constricted.

As for sizing swap & /var to the size of memory, the FAQ is focusing on retaining crash information for later diagnosis. It is up to you to decide whether you want to maintain such information. Yes, it can be educational, but you have also stated that the purpose of this USB install is to use public computers -- computers which aren't yours.

A controversial subject is whether swap is needed at all. Traditionally, swap was to be a backup for RAM which was very expensive at the time. Systems did not have hordes of RAM, so being able to use slower secondary storage (drive space) as overflow needed by hungry applications was seen as a reasonable compromise which allowed the system to keep running. Now that memory is abundant & cheap, it is questionable how useful swap is today. It can still be seen as insurance, but this comes out of what disk space is available -- which in this case is quite limited. You can watch how much swap is being used through applications such as systat(1) or top(1) I suspect that for systems sporting gigabytes of memory, swap is never used, but this is dependent upon what applications are being executed.

So given the limited amount of storage space available in a 4-8GB flash drive, I question whether you want to maintain space for crashes. I suspect you can get along just fine with setting swap to 32MB just to have some insurance. Going with no swap is simply gutsy.

When disk space becomes so important, you may also want to think about moving /tmp to RAM. Study mfs(8) & fstab(5) first. However, by moving /tmp into RAM within /etc/fstab, you are making an assumption that the configured amount of memory is available on all computers used. Think about this if you set this up in /etc/fstab.

Lastly with respect to having space for applications installed through packages, maximize the amount of space available to /usr if you are still creating individual partitions. I have one of the original 4GB Asus Eee netbooks, & although I have to think about what applications are really necessary, I have had OpenOffice (which is one of the largest applications in OpenBSD's ports tree...) installed.

As stated before, don't expect to get it all right the first time. Decide on what appears to be reasonable, & use it for awhile. After living with it, you will find nits that you want to change, & that is okay. Installation isn't that hard, & as long as you backup the important files, reinstalling shouldn't be very painful.
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Old 17th August 2010
IronForge IronForge is offline
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Default Will check out your references.

Thank a million, Ocicat.

Enjoy your day.
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Old 29th August 2010
IronForge IronForge is offline
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Default Mixed results

Greetings again:

I tried to go with the "/" partition only approach; but the resultant 8GB USB Drive wouldn't boot. I was successful in installing a Snapshot(Aug 24) a few days ago to a 4GB Drive I had (used the whole Drive and the automated partition arrangements. I traded in the 8GB (turns out it had some firmware I couldn't wipe) for a 16GB on sale.

I installed the Snapshot on the drive yesterday; and added some packages (OpenOffice, Mozilla-Firefox, etc). When I booted the USB this AM, Mozilla wouldn't remember the Search Engines I added(other add-ons were there); and the session froze completely.

Powering down and gave it another go; but it wouldn't boot - due to some partition problems...

I decided to reinstall and attempted to do so via ftp; but had some problems with the install process - kept dying when attempting to install the last set (Xserver). Burned another install48.iso image from today and had the same deal with the cd sets and the ftp derived sets. Burned cd48.iso and had the same results.

Various error codes include the term:
"fatal panic (6) in supervisor mode"

My questions are:
A1) Was today's snapshot a "bad build"?
A2) Could the USB have become faulty? I read Ocicat's comments regarding memtest - will look it up. I had some problems with several USB drives in the front of my old box with OBSD from time to time. IIRC, I modified the kernel (from an earlier thread - running out of time now to look up, gomen). Would it be prudent to do so?

Thanks.
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Old 29th August 2010
ocicat ocicat is offline
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Quote:
Originally Posted by IronForge View Post
Various error codes include the term:
"fatal panic (6) in supervisor mode"
You should take the time to study the crash(8) manpage if you want to delve into causes.
Quote:
Was today's snapshot a "bad build"?
I assume you are referring to the last August 24 i386 build. I have been using this snapshot intensely this weekend without issue.
Quote:
I had some problems with several USB drives in the front of my old box with OBSD from time to time.
So, there is some historic precedent here. You may want to consider adding a USB PCI card (~$25US) to see if this circumvents these problems.
Quote:
IIRC, I modified the kernel...


Installed on the USB drive? You need to fully disclose all details of customization. It is also advisable to keep a copy of the original snapshot kernel (I append the snapshot's date to a copy immediately after installing...) for testing/insurance reasons.

The etiquette of the official misc@ mailing list is to drop any discussion of systems found having custom kernels. Diagnosing such frankensystems is simply too involved to be worth the effort.

In short, it sounds you are having hardware compatibility issues. It is impossible to pinpoint the USB flash drive as the culprit given the known flaky nature of the computer's USB subsystem.
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Old 29th August 2010
IronForge IronForge is offline
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Clarification:

I modified the kernel on my old PC Workstation - months ago. My apologies for the confusion.

I'm trying to figure out why I was able to install on two separate USBs (4GB and 16GB) - yet one system that I added packages to freezes up; and I'm unable to reinstall OBSD onto that USB. With 16GBs (on sale this week(fri-thu) at 8GB prices (at a store chain that shares a name with a Futurama Character - in case anyone's interested) , there should be plenty of room.

Will read up on this - thank you.
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Old 29th August 2010
ocicat ocicat is offline
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Quote:
Originally Posted by IronForge View Post
I'm trying to figure out why I was able to install on two separate USBs (4GB and 16GB) - yet one system that I added packages to freezes up; and I'm unable to reinstall OBSD onto that USB.
I have heard/read stories about the wide variations in USB flash drive quality; anything from some being extremely slow, to others being incompatible, & yet others prematurely dying. However, some claim that their flash devices have been impervious even after being run through a washing machine -- sometimes several times.

As for my direct experience, I have yet to have issues with mine, but I also don't use them excessively or run them through washing machines.

With the information provided, it sounds like you have an item which should either be returned or thrown simply away. Given that the price of 4GB flash drives are now somewhere in the vicinity of ~$10US, I suspect most aren't going to bother finding root causes anymore.
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