If the disk is constant angular velocity (ie there is no shear between the inside and outside of the disk) then all portions of the platter go through the same amount of revolutions.

In the case of a 5400 rpm drive, every particle on the plater rotates about the axis 10800pi radians every minute.

The linear speed varies in a constant angular drive, so ideally you’d want the swap to be on the outside so it’s real fast. You might also want to have the /boot on the outside too.

One needs to be careful however, since sectors are indexed starting from the outside on constant angular velocity drives. Sector 0 /is/ the outside of the disk. This is different than constant linear velocity drives like cds and dvds where the first sector is actually on the inside of the disk. I hope that helps.

Isn’t it the other way around? The disk is round so the center turns faster. You’d want swap at the begining or center of the hard disk.

I was looking into nodiratime, and it looks like if you flag ext2/3(/4?) with noatime, you automatically get nodiratime too. I’m going by the discussion here, where the source code seems to show as much.

http://lwn.net/Articles/244829/

From my own experimenting, my boot and access times are almost identical with noatime, and then with noatime and nodiratime. But it’s useful nonetheless.

I’m still looking at the other two tweaks, since I don’t have an ext3 partition built right now. Thanks again!

Thanks for this great Howto and summarising all these tweaks. Did you know, that beside the “noatime”-Option, there’s also “nodiratime” and further more “nobh” for ext2/3/4-filesystems.

“noatime” disables, that every last access time for files is stored, and “nodiratime” does that for directories, as far as I know. For non-Server or home-use-system there are, imho, no disadvantages only improvements, when using this options.

“nobh” (also for /etc/fstab) I found in the kernel documentation, it says:
(found in /(kernel)/Documentation/filesystems/ext3.txt)

“bh (*) ext3 associates buffer heads to data pages to

nobh (a) cache disk block mapping information
(b) link pages into transaction to provide
ordering guarantees.
“bh” option forces use of buffer heads.
“nobh” option tries to avoid associating buffer
heads (supported only for “writeback” mode).
”

I guess it means some improvement when using data=writeback.

By the way, I read that ext2 is thus old much faster than ext3, because of no journal function. So maybe it’s a good idead, to make e.g. /tmp as an extra ext2-partition. (directories with non-important data)

Also excited about ext4dev with its “extents” feature.

One last thing I found:
For ext3/ext4dev there’s the “commit=(seconds)” option. In default it’s 5 seconds (commit=5), you can change that to commit=100 e.g. It’s not good for unstable systems, because with a crash, you maybe have more data loss. But I thingk it improves performance. There’s also a paragragh in the ext3-Kernel-documentation.

Thanks again for this howto! I guess you can add safely the “nodiratime” option. Have a look at the other options.

@Sindhudweep Sarkar: I know very well how to calculate it.

I don’t know how to understand the output of tcpdump: it writes as an intro something like ‘link-type EN10MB (Ethernet)’. Shouldn’t it be EN100MB or am i wrong?