[转载] strip 、 stripe 和chunk的概念

说句实话，对于存储里面 strip 和 stripe 这样基础的概念，一直都在术语层面有些混淆(英文拼写太相近了)，实在有些丢脸。好在看到了一个帖子，发现没有分清strip和stripe的还远远不止我一个，呵呵

http://bbs.doit.com.cn/viewthread.php?tid=63290

其实看看下面的图，就清楚两者的区别了. 从英语本意来讲，记住 stripe  比 strip  更"长"就不会弄混淆了。

strip是"条", 有一块的意思:

long narrow piece (of material, etc) or area (of land, etc)

Stripe 是条纹:

long narrow band (usu of the same width throughout its length) on a surface that is usu different from it in colour, material or texture

从我的理解而言：

stripe size = strip size * stripe depth

stripe = chunk / strip size = chunk size

block 基本上可以认为就是 sector

extent
1. [Storage System] A set of consecutively addressed FBA disk blocks that is allocated to consecutive addresses of a single file.
2. [Storage System] A set of consecutively located tracks on a CKD disk that is allocated to a single file.
3. [Storage System] A set of consecutively addressed disk blocks that is part of a single virtual disk-to-member disk array mapping.
A single disk may be organized into multiple extents of different sizes, and may have multiple (possibly) non-adjacent extents that are part of the same virtual disk-to-member disk array mapping. This type of extent is sometimes called a logical disk.
strip
[Storage System] The consecutively addressed blocks in a single extent.
A disk array‘s controller uses strips to map virtual disk block addresses to member disk block addresses. Also known as stripe element.
strip size
[Storage System] Synonym for stripe depth.
stripe
[Storage System] The set of strips at corresponding locations of each member extent of a disk array that uses striped data mapping.
The strips in a stripe are associated with each other in a way (e.g., relative extent block addresses) that allows membership in the stripe to be quickly and uniquely determined by a computational algorithm. Parity RAID uses stripes to map virtual disk block addresses to member extent block addresses.
stripe depth
1. [Storage System] The number of blocks in a strip in a disk array that uses striped data mapping.
2. [Storage System] The number of consecutively addressed virtual disk blocks mapped to consecutively addressed blocks on a single member extent of a disk array.
stripe element
[Storage System] Synonym for strip.
stripe size
[Storage System] The number of blocks in a stripe.
A striped array‘s stripe size is the stripe depth multiplied by the number of member extents. A parity RAID array‘s stripe size is the stripe depth multiplied by the number of member extents less the number of parity extents.
chunk
[Storage System] Synonym for strip.
chunk size
[Storage System] Synonym for stripe depth and strip size.
block
1. [Storage System] The unit in which data is stored and retrieved on disk and tape devices; the atomic unit of data recognition (through a preamble and block header) and protection (through a CRC or ECC).
2. [Fibre Channel] A unit of application data from a single information category that is transferred within a single sequence