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Last update 2001/03/27
Mass-Storage Approach
Tracks A track is a lane on a disk (a harddisk may have 16+ disks), track 0 is usually the most outer, and track 1 the next inside and so forth.
Cylinders Since a harddisk is composed by multiple disks, each lane on a disk (a track) can be viewed as a cylinder which the heads on each disk can access. There isn't much difference of tracks and cylinders, a track is viewed just one disk, whereas a cylinder is a track on all disks.
Sectors Each track is split into several sectors which is in most cased 512 bytes. E.g. a track has 63 sectors.
Heads Every harddisk has usually more one disks (a floppy-disk has just one), and usually there is a read- and write-head for each disk, e.g. IBM 18LZX (18GB, 10krpm, 4.9ms) has 5 disks, and 10 heads therefore.
Query You can query the disk-geomertry under *BSD using disklabel:
% disklabel /dev/da1s1e ...... bytes/sector: 512 sectors/track: 63 tracks/cylinder: 255 sectors/cylinder: 16065 cylinders: 2230 sectors/unit: 35840952 .... The number of heads you may have to lookup from your datasheet.
CCD Under *BSD system you can use CCD to concate several disks together. Check FreeBSD-section about how to set it up.
VINUM Another improvded software raid approach for *BSD based systems.
The FreeBSD Diary: VINUM How to setup vinum
Linux RAID Since Kernel-2.4 Linux has now also Software RAID (beforeit required kernel-patches).
Linux 2.4: RAID How to setup software RAID
Another way to speed up disk-access is to copy the content into a memory-based filesystem (MFS or also RAMDISK called).
Linux: RAMDisk ramdisks under linux FreeBSD: Memory FS mfs under freebsd
StorageReview.Com many worthwhile tech background infos
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