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Looking at Fedora 14 and Ubuntu 10.10

Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 8, 2010 21:12 UTC (Wed) by cjwatson (subscriber, #7322)
In reply to: Looking at Fedora 14 and Ubuntu 10.10 by Frej
Parent article: Looking at Fedora 14 and Ubuntu 10.10

I'm afraid that isn't accurate.

The Ubuntu installer has always been based on the Debian installer ("d-i"), and given our heritage as a distribution it makes a lot of sense to take that route. While the version you see on Ubuntu desktop CDs has a customised frontend, much of the backend code is shared with d-i, and this is particularly so for the partitioner - partitioning code is sufficiently delicate that we have no desire to maintain two entirely separate versions of it!

d-i's partitioner is called partman, and it's been used in all versions of Debian since 2004 or so, and in all versions of Ubuntu. We have contributed extensively to d-i over the years, and I'm one of the primary developers of partman among other things. (I guess it isn't fashionable to regard Debian as an upstream or something, but in this case it certainly is.) Like many partitioners, partman uses libparted, one of whose maintainers indeed works for Red Hat.

If you select "Specify partitions manually (advanced)" in the current Ubuntu graphical partitioner, you'll get something that's essentially a graphical rendering of partman's dialogs (though there are a couple of features missing). I wrote that graphical frontend for Ubuntu, and it has not been changed much in 10.10. The big changes are in the automatic partitioner, whose job it is to supply a small number of clear common-case options; Michael Forrest gave us a new design for that, and Evan Dandrea implemented it. Those changes, the ones mentioned in the main article, can and should be credited to Ubuntu.


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Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 8, 2010 21:58 UTC (Wed) by jspaleta (subscriber, #50639) [Link]

Credited to Ubuntu? Or Credited to Canonical?

-jef

Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 8, 2010 22:21 UTC (Wed) by cjwatson (subscriber, #7322) [Link]

Whichever you prefer.

Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 21, 2010 10:07 UTC (Tue) by Wol (guest, #4433) [Link]

I hope you haven't repeated the mistake in the SuSE partitioner ...

On a 2Gb ram machine it gave me a default 2Gb swap. This machine dual-boots gentoo, and I *need* 10Gb usable memory (to compile OOo). Would SuSE let me increase the size of the swap partition? No it wouldn't! Even shrinking another partition to make room it refused to give me more swap :-( It seems all are capped at whatever SuSE thinks is the best default, and all you can do is free up space, not reuse it elsewhere :-(

And my default rule for swap anyway is (given that disk is cheap) is "twice max ram" which on my mobo is 32Gb. People have been saying "the twice ram rule is obsolete" since before linux was born ... then 2.4 proved they were wrong! I haven't seen anything (yes I know there's been some major rewrite since then) that says the actual underlying algorithm has changed, so I still stick to the rule. If it still holds it means there's some (minor) performance hit if you have less ram.

Cheers,
Wol

Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 24, 2010 12:55 UTC (Fri) by nix (subscriber, #2304) [Link]

Well, it all depends on what you're using it for. On my desktop (a 12Gb Nehalem), I'm using twice RAM simply because I'm suspending to swap when not in use, and I'd rather like to find I can suspend even if I happen to have launched a monster 20Gb compilation, thank you very much. On the server holding my home directory, though, I don't bother: the machine runs good few VMs, so it has 24Gb RAM, and the max RAM on that motherboard is 128Gb. I'm not configuring 256Gb swap, thanks! I configured 24Gb swap and I think that was probably too much: I've never seen more than 6Gb in use.

The rule for swap is really 'configure as much as you need'. Swap partitions aren't much faster than swapfiles these days, so adding swap as needed isn't penalized anymore.

Looking at Fedora 14 and Ubuntu 10.10

Posted Sep 25, 2010 20:24 UTC (Sat) by gvy (guest, #11981) [Link]

> And my default rule for swap anyway is (given that disk is cheap)
> is "twice max ram" which on my mobo is 32Gb.
So I should do 48G swap on an 1U server by that rule, and have done only 2G given 4G RAM. Ouch.

Did you consider multiple swap partitions, or emergency swap files (which aren't as nice as swap partitions/spindles but hey, if you need that much virtual memory actively you should go after more RAM)?

> People have been saying "the twice ram rule is obsolete" since before
> linux was born ...
I'm not to cry "prooflink!!11" but for 4, 8, 16, 32M RAM it was perfectly the rule. Somewhere near 64M RAM things became less apparent for desktop as working set more or less got into that plus 1x swap.

> then 2.4 proved they were wrong!
There were quite a few VM managers for 2.4.x, and at some time a bug has caused the "need" in 2x swap which is probably what you heard and recall when it was long fixed.

My main reasons for large swap these days are tmpfs for hasher package builds (with swap on 15kRPM SAS drives, and not heavily used -- rather "just to free up memory before having to clean up") and hiberation (where again, I have a hard time filling up RAM to get all of the RAM+VRAM+tinybit swap used by hibernation alone).

My, and probably yours either, main reason *not* to do uselessly large swaps is the time needed to write or read it all. If you're not going to wait for minutes, that is -- hdparm -t/-T will help to estimate both hard disk's and RAM read speed, and bc -l to turn that into full swap read time.


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