sd 5.6 KB

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  1. .TH SD 3
  2. .SH NAME
  3. sd \- storage device interface
  4. .SH SYNOPSIS
  5. .nf
  6. .B bind #S /dev
  7. .sp 0.4v
  8. .B /dev/sdctl
  9. .BI /dev/sd Cu /ctl
  10. .BI /dev/sd Cu /raw
  11. .BI /dev/sd Cu /data
  12. \&...
  13. .fi
  14. .SH DESCRIPTION
  15. The storage device interface serves a two-level directory
  16. giving access to multiple storage units,
  17. typically ATA(PI) or SCSI discs.
  18. Each unit
  19. is accessed via files in the directory named by the controller
  20. to which it is attached,
  21. .IR C ,
  22. and by its unit number
  23. .IR u .
  24. The controller naming convention for ATA(PI) units starts
  25. with the first controller being named
  26. .LR C ,
  27. the second
  28. .LR D ,
  29. etc. up to a maximum of 4 controllers
  30. .RB ([ C-F ]);
  31. legacy controllers are always 'C' and 'D'.
  32. There can be a maximum of 2 units per ATA(PI) controller
  33. .RB ([ 01 ]).
  34. The controller naming convention for SCSI units starts with
  35. the first controller being named
  36. .LR 0 ,
  37. the second
  38. .LR 1 ,
  39. etc. up to a maximum of 16 controllers
  40. .RB ([ 0-9a-f ]).
  41. There can be a maximum of 16 units per SCSI controller
  42. .RB ([ 0-9a-f ]).
  43. .PP
  44. Units are not accessed before the first attach.
  45. Units may be individually attached using the attach specifier,
  46. for example
  47. .IP
  48. .EX
  49. bind -a '#SsdD0' /dev
  50. .EE
  51. .PP
  52. An attach without a specifier will cause the driver to scan for all possible
  53. units before processing the rest of the name.
  54. .PP
  55. The subdirectory for each unit contains two files,
  56. .I ctl
  57. and
  58. .IR raw .
  59. In addition,
  60. if the unit is a direct-access disc of some type
  61. it may be split into partitions and
  62. the subdirectory may contain a file per partition.
  63. By default,
  64. the partition
  65. .I data
  66. will exist for such media.
  67. .SS "\fIctl\fP and partitions
  68. Partitions are added and deleted by writing to the
  69. .I ctl
  70. file
  71. .IP
  72. .EX
  73. part \f2name start-sector end-sector\fP
  74. delpart \f2name\fP
  75. .EE
  76. .PP
  77. The default
  78. .I data
  79. partition may be deleted.
  80. A partition cannot be deleted if a process has it open.
  81. If a change of removable media is detected,
  82. the new media cannot be opened until all open partitions
  83. on the old media are closed.
  84. .PP
  85. Partitions are usually created using
  86. .I fdisk
  87. and
  88. .IR prep (8);
  89. the convention is to name non-Plan 9 partitions after their corresponding operating systems
  90. (e.g.,
  91. .BR /dev/sdC0/dos )
  92. and Plan 9 partitions according to their function
  93. (e.g.,
  94. .BR /dev/sdC0/swap ).
  95. The example in
  96. .IR prep (8)
  97. shows how.
  98. .PP
  99. Reading the
  100. .I ctl
  101. file returns at least one line of textual information about
  102. the unit.
  103. The first line will always be prefixed by
  104. .L inquiry
  105. and will give a manufacturer and model number if possible.
  106. A line prefixed by
  107. .L config
  108. will be returned for appropriate media,
  109. e.g. for ATA(PI) units the remainder of the line contains
  110. configuration information from the device's
  111. .I identify
  112. command (config and capabilities)
  113. and also the available I/O transfer options;
  114. this is a diagnostic aid.
  115. A line prefixed by
  116. .L geometry
  117. will be returned for appropriate media;
  118. at least two numbers will follow,
  119. the first being the number of sectors contained in the unit
  120. and the second the sector size in bytes.
  121. Any remaining information on the
  122. .B geometry
  123. line is unit-dependent,
  124. for instance, head,
  125. cylinder and sector counts for ATA discs.
  126. If any partitions are defined for the media,
  127. their name, start-sector and end-sector will be returned,
  128. prefixed by
  129. .LR part .
  130. .IP
  131. .EX
  132. % cat /dev/sdD0/ctl
  133. inquiry KENWOOD CD-ROM UCR-421 208E10/20/99 7.39 2 M0
  134. config 85C0 capabilities 0F00 dma 00550004 dmactl 00000000
  135. geometry 242725 2352
  136. part data 0 242725
  137. %
  138. .EE
  139. .PP
  140. The use of DMA and multi-sector read/write commands may be
  141. enabled and disabled on ATA(PI) units by writing to the
  142. .B ctl
  143. file
  144. .B dma
  145. and
  146. .B rwm
  147. respectively followed by
  148. .B on
  149. or
  150. .BR off .
  151. For example, to enable DMA on a unit that supports it:
  152. .IP
  153. .EX
  154. % echo 'dma on'>/dev/sd00/ctl
  155. .EE
  156. .PP
  157. If supported by the unit,
  158. the standby timer may be enabled:
  159. .IP
  160. .EX
  161. % echo 'standby \f2T\fP'>/dev/sdC0/ctl
  162. .EE
  163. .PP
  164. where
  165. .I T
  166. is the standby timer period in seconds.
  167. .I T
  168. must be between 30 and 1200,
  169. or can be 0 to disable the timer.
  170. .SS \fIraw\fP
  171. The
  172. .I raw
  173. file is used to execute an arbitrary command on the unit at
  174. a low level.
  175. This is used by programs such as
  176. .IR scuzz (8)
  177. to manipulate devices that do not fit the simple storage model
  178. or for maintenance purposes.
  179. The following steps may be taken to execute a command
  180. .IP \- 3
  181. Write the command to the
  182. .I raw
  183. file;
  184. .IP \-
  185. Read or write data associated with the command, according to the direction of the transfer.
  186. .IP \-
  187. Read the
  188. .I raw
  189. file to retrieve the status of the command,
  190. returned as a text integer.
  191. .SS sdctl
  192. Reading
  193. .B /dev/sdctl
  194. yields information about each controller,
  195. one line per controller.
  196. Writing `\fLconfig\fI message\fR' to
  197. .B /dev/sdctl
  198. passes
  199. .I message
  200. to the legacy configuration machinery,
  201. used to set attributes such as IRQ, port and size.
  202. Writing `\fIctltype message\fR' to
  203. .B /dev/sdctl
  204. passes
  205. .I message
  206. to
  207. .IR ctltype 's
  208. .B wtopctl
  209. function with a nil
  210. .B sdev
  211. argument,
  212. where
  213. .I ctltype
  214. is a known controller type such as
  215. .B ata
  216. or
  217. .BR scsi .
  218. Writing `\c
  219. .BI sd "ctlletter message\fR'
  220. to
  221. .B /dev/sdctl
  222. passes
  223. .I message
  224. to
  225. .BI sd ctlletter\fR's
  226. .B wtopctl
  227. function with an
  228. .B sdev
  229. argument corresponding to the named controller,
  230. where
  231. .I ctlletter
  232. is a known controller letter such as
  233. .B C
  234. or
  235. .BR 0 .
  236. .SH SOURCE
  237. .B /sys/src/9/port/devsd.c
  238. .br
  239. .B /sys/src/9/*/sd*.[hc]
  240. .SH SEE ALSO
  241. .IR scuzz (8)
  242. .SH BUGS
  243. LUNs (logical unit numbers) are not implemented.
  244. For (S)ATA drives,
  245. LUNs are not merely ignored but are actively
  246. prevented from working except for INQUIRY commands.
  247. .PP
  248. The 4 controller limit for ATA(PI) is not enforced.
  249. .PP
  250. No account is taken of some buggy ATA PCI controllers
  251. such as the CMD640.
  252. .PP
  253. ATA(PI) units come up with DMA and multi-sector read/write
  254. capability disabled.