On Mon, 2005-07-18 at 11:43 +0100, Kevanf1 wrote:

On 18/07/05, James Knott wrote:

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I think you always want your swap partition on high disk. One disk revolution moves more data on the outer part of the disk than on the inner part. Like being on the edge of a merry go-around instead of at the center, it's moving faster. For swapping in and out of memory, I would think that would be the best setup.

How does one know where on the platter "high disk" is?

I would imagine that is a job left to the operating system. Hence there being a specific 'swap' partition in Linux.

I always thought the track 0 was at the inner most part of the disk. Keep in mind that on older systems they had a problem if the boot partition was more than 1024 sectors, hence the reason most people got into the habit of creating a small boot partition at the beginning of the disk. As the OP stated this is an older system perhaps this is needed here. -- Ken Schneider UNIX since 1989, linux since 1994, SuSE since 1998 "The day Microsoft makes something that doesn't suck is probably the day they start making vacuum cleaners." -Ernst Jan Plugge

Kevan, On Monday 18 July 2005 03:43, Kevanf1 wrote:

On 18/07/05, James Knott wrote:

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I think you always want your swap partition on high disk. One disk revolution moves more data on the outer part of the disk than on the inner part. Like being on the edge of a merry go-around instead of at the center, it's moving faster. For swapping in and out of memory, I would think that would be the best setup.

How does one know where on the platter "high disk" is?

I would imagine that is a job left to the operating system. Hence there being a specific 'swap' partition in Linux.

No. the OS does not make such a determination. The disk partitions (the number in, e.g., /dev/hda0) represent contiguous portions of the disk in a strict order from inside to outside or vice versa. (I now forget which the convention is, but I think it's the opposite of CDs / DVDs. They start at the inside and go outward. Hard drives, if I'm not mistaken, start at the outside with partition 0 and move inward) The fact that a partition is labelled a swap partition is mostly redundant (not strictly necessary), but it prevents the system from swapping on a file systerm partition or one of the mkfs series of programs from creating a file system in a swap partition. But where the swap goes (which disk and which partition) is up to the person configuring the system.

-- Take care. Kevan Farmer

Randall Schulz

Greg, On Monday 18 July 2005 07:27, Greg Wallace wrote:

-----Original Message-----

On Monday, July 18, 2005 @ 5:40 AM, Randall Schulz wrote: ...

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The disk partitions (the number in, e.g., /dev/hda0) represent contiguous portions of the disk in a strict order from inside to outside or vice versa. (I now forget which the convention is, but I think it's the opposite of CDs / DVDs. They start at the inside and go outward. Hard drives, if I'm not mistaken, start at the outside with partition 0 and move inward)

I would have thought CDs and DVDs would work the same as hard drives (working from the outside in).

And yet, that's how it is. Look at some partially recorded CDs and you'll see that the recorded area is always at the center and proceeding varying distances out from there, depending on how much is recorded on the disc.

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The fact that a partition is labelled a swap partition is mostly redundant (not strictly necessary), but it prevents the system from swapping on a file systerm partition or one of the mkfs series of programs from creating a file system in a swap partition.

So the space is set aside for memory swapping, thus "swap", right? And, as you say, the os won't store any permanent files there. The os can then dump RAM buffers into it in whole, starting right at the beginning of the swap space and moving forward, without worrying about stepping on any files.

Yes. They're segregated. In fact, in the old days (and quite possibly on other, non-Linux, Unix-like systems, still today) swap area could share a partition with a file system. The file system would be formatted for less than the full capacity of the partition and the swap space would be created beginning after the end of the file system area).

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But where the swap goes (which disk and which partition) is up to the person configuring the system.

At installation time, where Nick (Nick being the guy who started this thread, back in the day) is right now, right?

True. And with a modicum of care, you can reconfigure later, too.

Greg W

Randall Schulz

On Monday, July 18, 2005 @ 6:59 AM, Ken Schneider wrote:

On Mon, 2005-07-18 at 06:27 -0800, Greg Wallace wrote:

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-----Original Message----- On Monday, July 18, 2005 @ 5:40 AM, Randall Schulz wrote:

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Kevan,

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The disk partitions (the number in, e.g., /dev/hda0) represent contiguous portions of the disk in a strict order from inside to outside or vice versa. (I now forget which the convention is, but I think it's the opposite of CDs / DVDs. They start at the inside and go outward. Hard drives, if I'm not mistaken, start at the outside with partition 0 and move inward)

I would have thought CDs and DVDs would work the same as hard drives (working from the outside in).

No. Next time you burn a partial CD take a look at were it put the data. It starts at the inner most part and works toward the outside.

-- Ken Schneider UNIX since 1989, linux since 1994, SuSE since 1998

"The day Microsoft makes something that doesn't suck is probably the day they start making vacuum cleaners." -Ernst Jan Plugge

Sure enough. I had only payed casual attention to the surface of CDs before. As you say, you can see the area that has been burned (on the inside of the CD). Not sure what the rational would be for that, but maybe the speed at which it could pull and push data isn't a factor for CDs (or is so insignificant that other reasons for putting it on the inside would override them). Or maybe the data is packed tighter on the inside to offset the shorter tracks. Anyway, it seems counter-intuitive. Greg Wallace

On Monday, July 18, 2005 @ 9:06 PM, Randall Schulz wrote:

Greg,

On Monday 18 July 2005 16:34, Greg Wallace wrote:

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Sure enough. I had only payed casual attention to the surface of CDs before. As you say, you can see the area that has been burned (on the inside of the CD). Not sure what the rational would be for that, but maybe the speed at which it could pull and push data isn't a factor for CDs (or is so insignificant that other reasons for putting it on the inside would override them). Or maybe the data is packed tighter on the inside to offset the shorter tracks. Anyway, it seems counter-intuitive.

CDs are recorded at constant linear velocity, so the number of sectors per linear cm of recording is fixed, but the number of sectors per revolution is not (that would be constant angular velocity, formerly common among hard drives, but no longer so, I don't believe).

As such, it's irrelevant and arbitrary where recording starts.

On the other hand, damage to the surface is much more likely near the outer edge because that's where people handle them mostly, so by starting recording at the inside, only the fullest discs will experience the maximum likelihood of damage to recorded areas.

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Greg Wallace

Randall Schulz

Just to make sure I'm understanding this, are you saying that if I'm burning on the inside of a CD or DVD, the disk is actually rotating faster than if I'm burning on the outside? Greg W

On Monday, July 18, 2005 @ 10:13 PM, Randall Schulz wrote:

Greg,

On Monday 18 July 2005 22:42, Greg Wallace wrote:

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Just to make sure I'm understanding this, are you saying that if I'm burning on the inside of a CD or DVD, the disk is actually rotating faster than if I'm burning on the outside?

Indeed.

To learn more, search the Web for "CD DVD CLV CAV".

E.g.: http://a9.com/CD%20DVD%20CLV%20CAV

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Greg W

RRS

Interesting. I have no idea whether I have a CLV or CAV CD, but since it's several years old, it's probably CLV (sounds like CAV is somewhat new on the scene). Greg Wallace P. S.: Speaking of new technology, did you hear about the new TV's that show two programs simultaneously on the same screen? If you're sitting to the left of center, you see one program. If you're sitting to the right of center, you see another. I guess if two people were watching different programs they'd have to be wearing headphones so they could hear the audio for just the one they're seeing.

-----Original Message----- From: James Knott To: suse-linux-e@suse.com Date: Tue, 19 Jul 2005 05:55:19 -0400 Subject: Re: [SLE] swap space question in 9.3 install

Greg Wallace wrote:

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Just to make sure I'm understanding this, are you saying that if I'm burning on the inside of a CD or DVD, the disk is actually rotating faster than if I'm burning on the outside?

Assuming constant linear velocity, yes.

Actually this is pretty easy to see that CDs spin at different velocities. Back when I was in high school, I drove an old beater car (didn't we all?) and therefore couldn't afford an in-dash CD player. I had my handy portable unit (that I still have and it still works, go Pioneer!) connected through the tape deck to listen to music. The lid of the CD player was clear plastic. I know for a fact that if you start at track 1 (on the innermost portion of the disk) it spins much faster than if you progress to the last track on a disk. You can watch the spinning velocity change in this manner. I thought it was pretty neat when I discovered that 7 years ago, but that's far before I knew anything about computers or CDs for that matter. -Nick

Nick Jones wrote:

-----Original Message----- From: James Knott To: suse-linux-e@suse.com Date: Tue, 19 Jul 2005 05:55:19 -0400 Subject: Re: [SLE] swap space question in 9.3 install

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Greg Wallace wrote:

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Just to make sure I'm understanding this, are you saying that if I'm burning on the inside of a CD or DVD, the disk is actually rotating faster than if I'm burning on the outside? Assuming constant linear velocity, yes.

Actually this is pretty easy to see that CDs spin at different velocities.

While CDs generally spin at a constant linear velocity, the spec also allows for constant angular velocity. There is nothing to stop someone from making a CAV CD.

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Monday 2005-07-18 at 15:34 -0800, Greg Wallace wrote:

Sure enough. I had only payed casual attention to the surface of CDs before. As you say, you can see the area that has been burned (on the inside of the CD). Not sure what the rational would be for that, but maybe the speed at which it could pull and push data isn't a factor for CDs (or is so insignificant that other reasons for putting it on the inside would override them). Or maybe the data is packed tighter on the inside to offset the shorter tracks. Anyway, it seems counter-intuitive.

The reason is very simple: there are different CD sizes (diameter). You can put a mini CD in a big player and it works, because it starts reading at the center. - -- Cheers, Carlos Robinson -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFC4tdVtTMYHG2NR9URAgS5AJsGtA+n0gN4opwAHgj0Ndzer9TVSACZAUuQ Ud/ePBnYCZNRVO6VLmiGb54= =iJhu -----END PGP SIGNATURE-----

Greg Wallace wrote:

I would have thought CDs and DVDs would work the same as hard drives (working from the outside in).

No. CDs & DVDs start from the hub. You may recall the old vinyl records. The different sized disks had different start points, which made things more complex for turntables & changers. With all CDs & DVDs starting from the inside track, all disks, no matter what size, all start from the same point. With hard drives, it's irrelevant where "track 0" is.

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Monday 2005-07-18 at 16:53 -0800, Greg Wallace wrote:

It may be true that it's irrelevant where "track 0" is, but, physically, you can move data to and from a disk faster from the outside of it than from the inside. That's just pure physics at work.

That may be true. But...

Norton builds a utility called "Speed Disk" for Windows machines. That utility takes data that has been plopped toward the inside of a disk and moves it toward the outside of the disk. It significantly increases file access speed. I believe it actually also uses last access date, among maybe other factors, to decide the order in which to place the files on the outside of the disk. You can also tell it to move something to the inside of the disk if it's a file you use on a very infrequent basis, which leaves more available outer disk space for more frequently used files.

That utility (and similar uts) moved files not to place them near the edge or the center of the disk, but to have them near the start of the "logical disk" in dos/windows. The rationale is that the FAT table and the root directory are at that logical disk start, and that any file access needed first to access the directory tables and fat tables. Judiciously placing files on disk optimized head movement, that is the biggest time waster in disk access. Remember also that those tables were not cached by default (you could remove the floppy any time). - -- Cheers, Carlos Robinson -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFC4tm1tTMYHG2NR9URAjj6AJ4jmIQY4hxzxbryRrod7yuj51IvpQCfQEGc 3HCaW5aY/2WEwgwUmiiQpzA= =Sg4t -----END PGP SIGNATURE-----

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The first partition on my SuSE Linux box is a swap partition.

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Greg Wallace

I think you always want your swap partition on high disk. One disk revolution moves more data on the outer part of the disk than on the inner part. Like being on the edge of a merry go-around instead of at the

On Monday, July 18, 2005 @ -----Original Message----- From: James Knott [mailto:james.knott@rogers.com] Sent: Monday, July 18, 2005 1:55 AM To: suse-linux-e@suse.com Subject: Re: [SLE] swap space question in 9.3 install Greg Wallace wrote: center,

it's moving faster. For swapping in and out of memory, I would think that would be the best setup.

How does one know where on the platter "high disk" is?

I was under the impression that installation started at the outside of the disk and worked inward. Based on the order in which you specify them in your initial partitioning at installation time, I recall seeing offsets under partitioning that indicated the partitions started at low numbers for partition 1 and went up for each subsequent partition. Surely Linux would not, by default, start installing on the inside of the disk and work outward(?)! Isn't that the way all operating systems are installed, starting on the outside of the disk? If I am not correct here, I would be interested in knowing about it. Greg Wallace

On Monday, July 18, 2005 @ 4:47 AM, Jerry Feldman wrote:

I always try to allocate my sawp partition to try to minimize head movement. While, the disk geometry is relevant, head movement is a very significant factor. Most home users are going to allocate 1 partition for swap and 1 partition for Linux. In this case, placing swap before the Linux partition might be better.

But, if you want to do an analysis, take a look at where your busiest partition is. That could be /var because /var contains all the log files and spools.

If you have 2 drives, and one is a Linux drive and the other is a Windows drive, placing the swap on the Windows drive will have the advantage of not

affecting head movement on the Linux drive, and if it is on a separate IDE channel, swap I/O can be overlapped.

However, if your system is swapping excessively, then you need to add more memory.

-- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

From above -- While, the disk geometry is relevant, head movement is a very significant factor. Most home users are going to allocate 1 partition for swap and 1 partition for Linux. In this case, placing swap before the Linux partition might be better.

That was really the point I was trying to get across; i. e., that it does make a difference where you put swap. Linux defaults swap to the first partition and there is actually a reason for putting it there. Greg Wallace

On Monday 18 July 2005 15:12, Greg Wallace wrote:

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While, the disk geometry is relevant, head movement is a very significant factor. Most home users are going to allocate 1 partition for swap and 1 partition for Linux. In this case, placing swap before the Linux partition might be better.

That was really the point I was trying to get across; i. e., that it does make a difference where you put swap. Linux defaults swap to the first partition and there is actually a reason for putting it there.

Greg Wallace

On Monday, July 18, 2005 @ 4:28 PM, Nick Jones wrote:

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That was really the point I was trying to get across; i. e.,

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does make a difference where you put swap. Linux defaults swap to

that it the

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first partition and there is actually a reason for putting it there.

Greg Wallace

On this particlar machine, it wanted the boot partition as the first partition on the disk because the BIOS was four years old and it needed it there for booting purposes (or at least that's the way I interpret the messages that it spit out at me, I should have written them down, whoops). Also, for some reason, it wanted 900+MB of swap for a machine with 128mb of RAM. Who am I to argue? I went ahead with the reccomended setup and all went just fine. This box is only a test machine anyway for some web development work. Chances are it'll be reformatted and reinstalled many times over it's remaining lifetime.

Thanks -Nick

If your machine does indeed requires the first boot partition to be the first one on the disk, then I guess you have no choice. In any event, the setup you said you used "-Delete partition /dev/hda1 509.9 MB (Linux Swap) -Create boot partition 64.4 MB (/dev/hda1 with ext2) -Create swap partition 901.1 MB on /dev/hda2 -Create root partition 73.6 GB (/dev/hda3 with reiser)" should be fine. You only have swap offset 64.4 MB from the beginning, and that's a pretty insignificant offset from the beginning of the disk. You just want to, all other things being equal, try to keep swap toward the top of the disk. By the way, why did you use ext2 for boot and reiser for root? Just curious. Can you not have two reiser partitions on one system? Greg Wallace

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Monday 2005-07-18 at 17:27 -0800, Greg Wallace wrote:

By the way, why did you use ext2 for boot and reiser for root? Just curious. Can you not have two reiser partitions on one system?

The /boot partition is almost always ext2 because reiserfs requires at least 100MB. Also, the journal takes size, and it is pointless for a partition so small (it is always one or two tracks, 10 or 20 Mb or roundabouts). For the same reason, it is not ext3. - -- Cheers, Carlos Robinson -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFC4twTtTMYHG2NR9URApq2AJ4qAHpI8p98rgMAOrXoTOGDez/p/ACgiQBN zqto+B1Z8Vf4p20gAZh7HLw= =t+k+ -----END PGP SIGNATURE-----

-----Original Message----- From: Michael James To: suse-linux-e@suse.com Date: Tue, 19 Jul 2005 15:00:25 +1000 Subject: Re: [SLE] swap space question in 9.3 install

YOU want more than 128M of RAM. IT was just allowing for the day you get it. ;^)

Eh, I'm not keen on spending nearly $200 to bring it up to it's 512mb max. I think this machine can just sit headless in the closet and serve out MP3s and be a test web server for development work. I installed a minimal 9.3 system with Apache and Samba, and that's all I need it for. Thanks! -Nick

On Monday 18 July 2005 15:12, Greg Wallace wrote:

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While, the disk geometry is relevant, head movement is a very significant factor. Most home users are going to allocate 1 partition for swap and 1 partition for Linux. In this case, placing swap before the Linux

On Monday, July 18, 2005 @ 4:02 PM, Anders Johansson wrote: partition

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might be better.

That was really the point I was trying to get across; i. e., that it does make a difference where you put swap. Linux defaults swap to the first partition and there is actually a reason for putting it there.

If your disk starts swapping so much that you can tell the difference between one location on the disk and another, it will be the least of your worries.

Your system will be basically useless.

Swap is good in three cases

1. An application uses so much memory that you need to go in to swap to be able to let it run. Some multimedia editing programs are like that. There, speed of swap is almost totally irrelevant

2. To make room for cache. The kernel will move parts of memory that haven't been accessed in a long time to swap, so that more internal memory can be used to cache disk accesses. The speed of the swap is again almost totally irrelevant

3. To store memory images when you suspend to disk. Here you will want to make sure you have enough swap available to fit your memory image. But the speed

is relatively insignificant, since the access is on boot with nothing else running, there will be no massive seeking back and forth, and the relative difference in speed between inner and outer cylinders I seriously doubt will make much of an impact

But swap used for the general running of the system? Forget it. If it gets that far, you might as well give up

All true, but is there any reason to purposely move swap down during installation? If you move it down after your regular Linux partitions and that ends up putting it 40, 50, 60 G further down, I think that might make a noticeable difference in some cases. Of course, other factors will be at play, such as the speed of your connection (if you're moving data to an external device), etc., but why not set up you partitions in the best possible manner to begin with. Greg Wallace

Greg Wallace wrote:

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How does one know where on the platter "high disk" is?

I was under the impression that installation started at the outside of the disk and worked inward. Based on the order in which you specify them in your initial partitioning at installation time, I recall seeing offsets under partitioning that indicated the partitions started at low numbers for partition 1 and went up for each subsequent partition. Surely Linux would not, by default, start installing on the inside of the disk and work outward(?)! Isn't that the way all operating systems are installed, starting on the outside of the disk? If I am not correct here, I would be interested in knowing about it.

My point is, that the average user does not know which tracks correspond to the inner or outer areas of the disk. The manufacturer can have track 1 closest to the hub or to the outside. Add logical sector addressing, and a sector could theoretically be anywhere. I have even seen disks, where every other track, going into the hub was skipped, and then when the heads reached the inner track, the track count continued on the previously skipped tracks, so that the last track was physically right next to the first and the "middle" tracks, were actually right near the hub. I have also worked on "head per track" drives, where the tracks were not in sequential order.