partition order
I have a just a quick question about my partitions. I have setup like this:
Device ID System /dev/hda1 82 Swap /dev/hda2 5 Extended /dev/hda3 83 root /dev/hda4 83 user /dev/hda5 83 home So I wanted to know if having swap as the hda1 and then root on the extended (hda3) will cause me any trouble done the track? Should I reformat to have root as hda1? I have only just installed so a reformat should not be a problem, if I have to. |
Nope - that is no problem, and in fact there is no requirement for any primary partition(s) with Linux. Do it as you wish.
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great news, thanks
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No problem. Just a note, when you place the swap at the front of the disk, the access time should be better. If you place the swap at the end of the drive then the latency will increase. |
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I would have assumed that the time to access an arbitrary point on the disk would be random, but within a defined range. |
For 2.6 (well, actually 2.5+) kernels this is no longer an issue. If it ever was.
The I/O schedulers are asynchronous, and swap uses the same (disk) driver as normal I/O - this is also the reason swap datasets are no longer at a performance penalty as compared to swap partitions. Can't comment on 2.4 kernels - never looked at the code. |
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When speaking of the disk, the mechanical aspects of the subsystem still apply. We cannot get by the fact of the mechanical latency of a hard disk system. The only way around would be to use a ram based system. This would be cost prohibitive for the normal user. With the ram based (ramdisk) then you would be relying solely on the handler. As for the; Quote:
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If you have a modern system .. you probably don't need Swap either ...
A question btw, (probably should have started a new thread but what the hell) Isn't swap just some part of the memory stored onto the hardDisk. Then how come on my computer it shows that out of 1GB Ram , around 400MB RAM is used physical memory whereas 600 MB is swap? |
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Brian |
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1. It is far more complex than simply saying beginning or end of the drive. 2. It depends on the design of the drive 3. The normal user will never see the difference |
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[1] Yes it is. But to understand the basics of the HD subsystem for both electronics and mechanical does require a little background. Not everyone is up to speed with the designs of the HD. This Partitioning Primer is rather simplistic (plus old) but can be used to convey the basic idea. Another link with a HD, How fast is your disk? that test compares three type of HD. Mechanical is always going to be the limiting factor for HD subsystems, notice the rotation speeds for the above test link. Quote:
[3] Not necessarily so. That will depend on the age, design and even how the 'normal user' has the subsystem setup. Especially if the 'normal user' defaults to his/her distro defaults for the subsystem. The optimization for the drive should default to the drives abilities/configuration but not always true thus the 'normal user' may or may not see the performance difference. This could go on and on. I don't want to waste more time on the issue. There are loads of manufacture data for HD systems that can be used to understand the methods in detail that we have discussed generally. I would suggest for those interested to go to their drives manufacture website and read some of the white papers or technical data sheet(s). Real informative but can be lengthy as well as boring to some. |
Mmmm - let's say you put your swap on the "fastest" bit of the disk. On the same disk you have your mp3's, your logs, your shared executables ...
The heads are going to be all over the place - where's the benefit for swap ???. Besides which, calculate your I/O rate on your swap; on most systems it is so close to insignificant as to not even be worth worrying about. Not to mention the consolidation of (physical) I/O done by the I/O schedulers. I/O is not issued immediately, and it is also not issued in the order received. See the article on iostat on the site referenced above - note the comment (on the screenshots page) on the elevator (scheduler) doing its job. |
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