1dkio(7I) Ioctl Requests dkio(7I)
2
6 dkio - disk control operations
7
9 #include <sys/dkio.h>
10 #include <sys/vtoc.h>
11
14 Disk drivers support a set of ioctl(2) requests for disk controller,
15 geometry, and partition information. Basic to these ioctl() requests
16 are the definitions in <sys/dkio.h>.
17
19 The following ioctl() requests set and/or retrieve the current disk
20 controller, partitions, or geometry information on all architectures:
21 DKIOCINFO
23 The argument is a pointer to a dk_cinfo structure (described
25 below). This structure tells the controller-type and attributes
26 regarding bad-block processing done on the controller.
27 /*
30 * Structures and definitions for disk I/O control commands
31 */
32 #define DK_DEVLEN 16 /* device name max length, */
33 /* including unit # and NULL */
34 /* Used for controller info */
35 struct dk_cinfo {
36 char dki_cname[DK_DEVLEN]; /* controller name */
37 /* (no unit #) */
38 ushort_t dki_ctype; /* controller type */
39 ushort_t dki_flags; /* flags */
40 ushort_t dki_cnum; /* controller number */
41 uint_t dki_addr; /* controller address */
42 uint_t dki_space; /* controller bus type */
43 uint_t dki_prio; /* interrupt priority */
44 uint_t dki_vec; /* interrupt vector */
45 char dki_dname[DK_DEVLEN]; /* drive name (no unit #) */
46 uint_t dki_unit; /* unit number */
47 uint_t dki_slave; /* slave number */
48 ushort_t dki_partition; /* partition number */
49 ushort_t dki_maxtransfer; /* maximum transfer size */
50 /* in DEV_BSIZE */
51 };
53 /*
54 * Controller types
55 */
56 #define DKC_UNKNOWN 0
58 #define DKC_CDROM 1 /* CD-ROM, SCSI or other */
59 #define DKC_WDC2880 2
60 #define DKC_XXX_0 3 /* unassigned */
61 #define DKC_XXX_1 4 /* unassigned */
62 #define DKC_DSD5215 5
63 #define DKC_ACB4000 7
64 #define DKC_XXX_2 9 /* unassigned */
65 #define DKC_NCRFLOPPY 10
66 #define DKC_SMSFLOPPY 12
67 #define DKC_SCSI_CCS 13 /* SCSI CCS compatible */
68 #define DKC_INTEL82072 14 /* native floppy chip */
69 #define DKC_MD 16 /* meta-disk (virtual-disk) */
70 /* driver */
71 #define DKC_INTEL82077 19 /* 82077 floppy disk */
72 /* controller */
73 #define DKC_DIRECT 20 /* Intel direct attached */
74 /* device (IDE) */
75 #define DKC_PCMCIA_MEM 21 /* PCMCIA memory disk-like */
76 /* type */
77 #define DKC_PCMCIA_ATA 22 /* PCMCIA AT Attached type */
78 /*
80 * Sun reserves up through 1023
81 */
82 #define DKC_CUSTOMER_BASE 1024
84 /*
86 * Flags
87 */
88 #define DKI_BAD144 0x01 /* use DEC std 144 */
90 /* bad sector fwding */
91 #define DKI_MAPTRK 0x02 /* controller does */
92 /* track mapping */
93 #define DKI_FMTTRK 0x04 /* formats only full
94 /* track at a time*/
95 #define DKI_FMTVOL 0x08 /* formats only full */
96 /* volume at a time*/
97 #define DKI_FMTCYL 0x10 /* formats only full */
98 /* cylinders at a time*/
99 #define DKI_HEXUNIT 0x20 /* unit number printed as */
100 /* 3 hexdigits */
101 #define DKI_PCMCIA_PFD 0x40 /* PCMCIA pseudo-floppy */
102 /* memory card */
103 DKIOCGAPART
106 The argument is a pointer to a dk_allmap structure (described
108 below). This ioctl() gets the controller's notion of the current
109 partition table for disk drive.
110 DKIOCSAPART
113 The argument is a pointer to a dk_allmap structure (described
115 below). This ioctl() sets the controller's notion of the partition
116 table without changing the disk itself.
117 /*
120 * Partition map (part of dk_label)
121 */ struct dk_map {
122 daddr_t dkl_cylno; /* starting cylinder */
123 daddr_t dkl_nblk; /* number of blocks */
124 };
125 /*
126 * Used for all partitions
127 */
128 struct dk_allmap {
129 struct dk_map dka_map[NDKMAP];
130 };
131 DKIOCGGEOM The argument is a pointer to a dk_geom structure
134 (described below). This ioctl() gets the controller's
135 notion of the current geometry of the disk drive.
136 DKIOCSGEOM The argument is a pointer to a dk_geom structure
139 (described below). This ioctl() sets the controller's
140 notion of the geometry without changing the disk itself.
141 DKIOCGVTOC The argument is a pointer to a vtoc structure (described
144 below). This ioctl() returns the device's current volume
145 table of contents (VTOC.) For disks larger than 1TB,
146 DKIOCGEXTVTOC must be used instead.
147 DKIOCSVTOC The argument is a pointer to a vtoc structure (described
150 below). This ioctl() changes the VTOC associated with the
151 device. For disks larger than 1TB, DKIOCSEXTVTOC must be
152 used instead.
153 struct partition {
156 ushort_t p_tag; /* ID tag of partition */
157 ushort_t p_flag; /* permission flags */
158 daddr_t p_start; /* start sector of partition */
159 long p_size; /* # of blocks in partition */
160 };
161 If DKIOCSVTOC is used with a floppy diskette, the p_start field must be
165 the first sector of a cylinder. To compute the number of sectors per
166 cylinder, multiply the number of heads by the number of sectors per
167 track.
168 struct vtoc {
170 unsigned long v_bootinfo[3]; /* info needed by mboot
171 /* (unsupported)*/
172 unsigned long v_sanity; /* to verify vtoc */
173 /* sanity */
174 unsigned long v_version; /* layout version */
175 char v_volume[LEN_DKL_VVOL]; /* volume name */
176 ushort_t v_sectorsz;
177 sector size in bytes*/
178 ushort_t v_nparts;
179 number of partitions*/
180 unsigned long v_reserved[10]; /* free space */
181 struct partition v_part[V_NUMPAR]; /* partition headers */
182 time_t timestamp[V_NUMPAR]; /* partition timestamp */
183 /* (unsupported) */
184 char v_asciilabel[LEN_DKL_ASCII]; /* compatibility */
185 };
186 /*
188 * Partition permission flags
189 */
190 #define V_UNMNT 0x01 /* Unmountable partition */
192 #define V_RONLY 0x10 /* Read only */
193 /*
195 * Partition identification tags
196 */
197 #define V_UNASSIGNED 0x00 /* unassigned partition */
199 #define V_BOOT 0x01 /* Boot partition */
200 #define V_ROOT 0x02 /* Root filesystem */
201 #define V_SWAP 0x03 /* Swap filesystem */
202 #define V_USR 0x04 /* Usr filesystem */
203 #define V_BACKUP 0x05 /* full disk */
204 #define V_VAR 0x07 /* Var partition */
205 #define V_HOME 0x08 /* Home partition */
206 #define V_ALTSCTR 0x09 /* Alternate sector partition */
207 DKIOCGEXTVTOC
210 The argument is a pointer to an extvtoc structure (described
212 below). This ioctl returns the device's current volume table of
213 contents (VTOC). VTOC is extended to support a disk up to 2TB in
214 size. For disks larger than 1TB this ioctl must be used instead of
215 DKIOCGVTOC.
216 DKIOCSEXTVTOC
219 The argument is a pointer to an extvtoc structure (described
221 below). This ioctl changes the VTOC associated with the device.
222 VTOC is extended to support a disk up to 2TB in size. For disks
223 larger than 1TB this ioctl must be used instead of DKIOCSVTOC.
224 struct extpartition {
226 ushort_t p_tag; /* ID tag of partition */
227 ushort_t p_flag; /* permission flags */
228 ushort_t p_pad[2]; /* reserved */
229 diskaddr_t p_start; /* start sector no of partition */
230 diskaddr_t p_size; /* # of blocks in partition */
231 };
232 struct extvtoc {
235 uint64_t v_bootinfo[3]; /* info needed by mboot (unsupported) */
236 uint64_t v_sanity; /* to verify vtoc sanity */
237 uint64_t v_version; /* layout version */
238 char v_volume[LEN_DKL_VVOL]; /* volume name */
239 ushort_t v_sectorsz; /* sector size in bytes */
240 ushort_t v_nparts; /* number of partitions */
241 ushort_t pad[2];
242 uint64_t v_reserved[10];
243 struct extpartition v_part[V_NUMPAR]; /* partition headers */
244 uint64_t timestamp[V_NUMPAR]; /* partition timestamp (unsupported)*/
245 char v_asciilabel[LEN_DKL_ASCII]; /* for compatibility */
246 };
247 Partition permissions flags and identification tags
249 are defined the same as vtoc structure.
250 DKIOCEJECT
254 If the drive supports removable media, this ioctl() requests the
256 disk drive to eject its disk.
257 DKIOCREMOVABLE
260 The argument to this ioctl() is an integer. After successful com‐
262 pletion, this ioctl() sets that integer to a non-zero value if the
263 drive in question has removable media. If the media is not remov‐
264 able, the integer is set to 0.
265 DKIOCHOTPLUGGABLE
268 The argument to this ioctl() is an integer. After successful com‐
270 pletion, this ioctl() sets that integer to a non-zero value if the
271 drive in question is hotpluggable. If the media is not hotplug‐
272 gable, the integer is set to 0.
273 DKIOCSTATE
276 This ioctl() blocks until the state of the drive, inserted or
278 ejected, is changed. The argument is a pointer to a dkio_state,
279 enum, whose possible enumerations are listed below. The initial
280 value should be either the last reported state of the drive, or
281 DKIO_NONE. Upon return, the enum pointed to by the argument is
282 updated with the current state of the drive.
283 enum dkio_state {
285 DKIO_NONE, /* Return disk's current state */
286 DKIO_EJECTED, /* Disk state is 'ejected' */
287 DKIO_INSERTED /* Disk state is 'inserted' */
288 };
289 DKIOCLOCK
293 For devices with removable media, this ioctl() requests the disk
295 drive to lock the door.
296 DKIOCUNLOCK
299 For devices with removable media, this ioctl() requests the disk
301 drive to unlock the door.
302 DKIOCGMEDIAINFO
305 The argument to this ioctl() is a pointer to a dk_minfo structure.
307 The structure indicates the type of media or the command set pro‐
308 file used by the drive to operate on the media. The dk_minfo struc‐
309 ture also indicates the logical media block size the drive uses as
310 the basic unit block size of operation and the raw formatted capac‐
311 ity of the media in number of logical blocks.
312 DKIOCGMEDIAINFOEXT
315 The argument to this ioctl() is a pointer to a dk_minfo_ext struc‐
317 ture. The structure indicates the type of media or the command set
318 profile used by the drive to operate on the media. The dk_minfo_ext
319 structure also indicates the logical media block size the drive
320 uses as the basic unit block size of operation, the raw formatted
321 capacity of the media in number of logical blocks and the physical
322 block size of the media.
323 /*
326 * Used for media info or profile info
327 */
328 struct dk_minfo {
329 uint_t dki_media_type; /* Media type or profile info */
330 uint_t dki_lbsize; /* Logical blocksize of media */
331 diskaddr_t dki_capacity; /* Capacity as # of dki_lbsize blks */
332 };
333 /*
335 * Used for media info or profile info and physical blocksize
336 */
337 struct dk_minfo_ext {
338 uint_t dki_media_type; /* Media type or profile info */
339 uint_t dki_lbsize; /* Logical blocksize of media */
340 diskaddr_t dki_capacity; /* Capacity as # of dki_lbsize blks */
341 uint_t dki_pbsize; /* Physical blocksize of media */
342 };
343 /*
346 * Media types or profiles known
347 */
348 #define DK_UNKNOWN 0x00 /* Media inserted - type unknown */
349 /*
351 * SFF 8090 Specification Version 3, media types 0x01 - 0xfffe are
352 * retained to maintain compatibility with SFF8090. The following
353 * define the optical media type.
354 */
355 #define DK_MO_ERASABLE 0x03 /* MO Erasable */
356 #define DK_MO_WRITEONCE 0x04 /* MO Write once */
357 #define DK_AS_MO 0x05 /* AS MO */
358 #define DK_CDROM 0x08 /* CDROM */
359 #define DK_CDR 0x09 /* CD-R */
360 #define DK_CDRW 0x0A /* CD-RW */
361 #define DK_DVDROM 0x10 /* DVD-ROM */
362 #define DK_DVDR 0x11 /* DVD-R */
363 #define DK_DVDRAM 0x12 /* DVD_RAM or DVD-RW */
364 /*
366 * Media types for other rewritable magnetic media
367 */
368 #define DK_FIXED_DISK 0x10001 /* Fixed disk SCSI or otherwise */
369 #define DK_FLOPPY 0x10002 /* Floppy media */
370 #define DK_ZIP 0x10003 /* IOMEGA ZIP media */
371 #define DK_JAZ 0x10004 /* IOMEGA JAZ media */
372 If the media exists and the host can obtain a current profile list, the
376 command succeeds and returns the dk_minfo structure with data repre‐
377 senting that media.
378 If there is no media in the drive, the command fails and the host
381 returns an ENXIO error, indicating that it cannot gather the informa‐
382 tion requested.
383 If the profile list is not available, the host attempts to identify the
386 media-type based on the available information.
387 If identification is not possible, the host returns media type
390 DK_UNKNOWN. See NOTES for blocksize usage and capacity information.
391 DKIOCSMBOOT
393 The argument is a pointer to struct mboot.
395 Copies the mboot information supplied in the argument to the abso‐
397 lute sector 0 of the device. Prior to copying the information, this
398 ioctl() performs the following checks on the mboot data:
399 o Ensures that the signature field is set to 0xAA55.
401 o Ensures that partitions do not overlap.
403 o On SPARC platforms, determines if the device is a remov‐
405 able media.
406 If the above verification fails, errno is set to EINVAL and the
407 ioctl() command fails.
408 x86 Platforms — Upon successful write of mboot, the partition map
410 structure maintained in the driver is updated. If the new Solaris
411 partition is different from the previous one, the internal VTOC ta‐
412 ble maintained in the driver is set as follows:
413 If _SUNOS_VTOC_8 is defined:
415 Partition: 0. Start: 0. Capacity = Capacity of device.
417 Partition: 2. Start: 0. Capacity = Capacity of device.
419 If _SUNOS_VTOC_16 is defined:
421 Partition: 2. Start: 0. Size = Size specified in mboot - 2 cylin‐
423 ders.
424 Partition: 8. Start: 0. Size = Sectors/cylinder.
426 Partition: 9. Start: Sectors/cylinder. Size = 2 * sectors/cylinder
428 To determine if the Solaris partition has changed:
430 If either offset or the size of the Solaris partition is different
432 from the previous one then it shall be deemed to have changed. In
433 all other cases, the internal VTOC info remains as before.
434 SPARC Platforms — The VTOC label and mboot both occupy the same
436 location, namely sector 0. As a result, following the successful
437 write of mboot info, the internal VTOC table maintained in the
438 driver is set as follows:
439 Partition: 0. Start: 0. Size = Capacity of device.
441 Partition: 2. Start: 0. Size = Capacity of device.
443 See the NOTES section for usage of DKIOCSMBOOT when modifying
445 Solaris partitions.
446 DKIOCGETVOLCAP
449 This ioctl provides information and status of available capabili‐
451 ties.
452 vc_info is a bitmap and the valid flag values are:
454 DKV_ABR_CAP - Capable of application-based recovery
456 DKV_DMR_CAP - Ability to read specific copy of data when
457 multiple copies exist. For example, in a two
458 way mirror, this ioctl is used to read each
459 side of the mirror.
460 vc_set is a bitmap and the valid flag values are:
462 DKV_ABR_CAP - This flag is set if ABR has been set on a device
464 that supports ABR functionality.
465 DKV_DMR_CAP - Directed read has been enabled.
466 These capabilities are not required to be persistent across a sys‐
468 tem reboot and their persistence depends upon the implementation.
469 For example, if the ABR capability for a DRL mirror simply clears
470 the dirty-region list and subsequently stops updating this list,
471 there is no reason for persistence because the VM recovery is a no-
472 op. Conversely, if the ABR capability is applied to a non-DRL mir‐
473 ror to indicate that the VM should not perform a full recovery of
474 the mirror following a system crash, the capability must be persis‐
475 tent so that the VM know whether or not to perform recovery.
476 Return Errors:
478 EINVAL Invalid device for this operation.
480 ENOTSUP Functionality that is attempted to be set is not sup‐
483 ported.
484 DKIOCSETVOLCAP
488 This ioctl sets the available capabilities for the device. If a
490 capability flag is not set in vc_set, that capability is cleared.
491 vc_info flags are ignored
493 vc_set valid flags are:
495 DKV_ABR_CAP - Flag to set application-based recovery. A device can
497 successfully support ABR only if it is capable.
498 DKV_DMR_CAP - Flag to set directed read.
499 int
502 ioctl(int , DKIODMR, vol_directed_rd *);
503 DKIODMR
507 This ioctl allows highly available applications to perform round-
509 robin reads from the underlying devices of a replicated device.
510 vdr_offset - offset at which the read should occur.
512 vdr_nbytes - number of bytes to be read
513 vdr_bytesread - number of bytes successfully read by the kernel.
514 vdr_data - pointer to a user allocated buffer to return the
515 data read
516 vdr_side - side to be read. Initialized to DKV_SIDE_INIT
517 vdr_side_name - The volume name that has been read.
518 Valid vdr_flags are:
520 DKV_DMR_NEXT_SIDE (set by user)
521 DKV_DMR_DONE (return value)
522 DKV_DMR_ERROR (return value)
523 DKV_DMR_SUCCESS(return value)
524 DKV_DMR_SHORT(return value)
525 The calling sequence is as follows: The caller sets the vdr_flags
527 to DK_DMR_NEXT_SIDE and vdr_side to DKV_SIDE_INIT at the start.
528 Subsequent calls should be made without any changes to these val‐
529 ues. If they are changed the results of the ioctl are indetermi‐
530 nate.
531 When DKV_SIDE_INIT is set, the call results in the kernel reading
533 from the first side. The kernel updates vdr_side to indicate the
534 side that was read, and vdr_side_name to contain the name of that
535 side. vdr_data contains the data that was read. Therefore to per‐
536 form a round-robin read all of the valid sides, there is no need
537 for the caller to change the contents of vdr_side.
538 Subsequent ioctl calls result in reads from the next valid side
540 until all valid sides have been read. On success, the kernel sets
541 DKV_DMR_SUCCESS. The following table shows the values of vdr_flags
542 that are returned when an error occurs:
543 vdr_flags | vdr_side | Notes
545 -------------|-------------------|----------------------------
546 DKV_DMR_ERROR| DKV_SIDE_INIT | No valid side to read
547 DKV_DMR_DONE | Not Init side | All valid sides read
548 DKV_DMR_SHORT| Any value | Bytes requested cannot
549 be read. vdr_bytesread
550 set to bytes actually
551 read.
552 Typical code fragment:
555 enable->vc_set |= DKV_ABR_SET;
557 retval = ioctl(filedes, DKIOSETVOLCAP, enable);
558 if (retval != EINVAL || retval != ENOTSUP) {
559 if (info->vc_set & DKV_DMR_SET) {
560 dr->vdr_flags |= DKV_DMR_NEXT_SIDE;
561 dr->vdr_side = DKV_SIDE_INIT;
562 dr->vdr_nbytes = 1024;
563 dr->vdr_offset = 0xff00;
564 do {
565 rval =ioctl(fildes, DKIODMR, dr);
566 if (rval != EINVAL) {
567 /* Process data */
568 }
569 } while (rval != EINVAL || dr->vdr_flags &
570 (DKV_DMR_DONE | DKV_DMR_ERROR | DKV_DMR_SHORT)
571 }
572 }
573 RETURN VALUES
577 Upon successful completion, the value returned is 0. Otherwise, -1 is
578 returned and errno is set to indicate the error.
579 x86 Only
581 The following ioctl() requests set and/or retrieve the current disk
582 controller, partitions, or geometry information on the x86 architec‐
583 ture.
584 DKIOCG_PHYGEOM
586 The argument is a pointer to a dk_geom structure (described below).
588 This ioctl() gets the driver's notion of the physical geometry of
589 the disk drive. It is functionally identical to the DKIOCGGEOM
590 ioctl().
591 DKIOCG_VIRTGEOM
594 The argument is a pointer to a dk_geom structure (described below).
596 This ioctl() gets the controller's (and hence the driver's) notion
597 of the virtual geometry of the disk drive. Virtual geometry is a
598 view of the disk geometry maintained by the firmware in a host bus
599 adapter or disk controller. If the disk is larger than 8 Gbytes,
600 this ioctl fails because a CHS-based geometry is not relevant or
601 useful for this drive.
602 /*
605 * Definition of a disk's geometry
606 */
607 */struct dk_geom {
608 unsigned shor dkg_ncyl; /* # of data cylinders */
609 unsigned shor dkg_acyl; /* # of alternate cylinders */
610 unsigned short dkg_bcyl; /* cyl offset (for fixed head */
611 /* area) */
612 unsigned short dkg_nhead; /* # of heads */
613 unsigned short dkg_obs1; /* obsolete */
614 unsigned short dkg_nsect; /* # of sectors per track*/
615 unsigned short dkg_intrlv; /* interleave factor */
616 unsigned short dkg_obs2; /* obsolete */
617 unsigned short dkg_obs3; /* obsolete */
618 unsigned short dkg_apc; /* alternates per cylinder */
619 /* (SCSI only) */
620 unsigned short dkg_rpm; /* revolutions per min*/
621 unsigned short dkg_pcyl; /* # of physical cylinders */
622 unsigned short dkg_write_reinstruct; /* # sectors to skip, writes*/
623 unsigned short dkg_read_reinstruct; /* # sectors to skip, reads*/
624 unsigned short dkg_extra[7]; /* for compatible expansion*/
625 };
626 DKIOCADDBAD
629 This ioctl() forces the driver to re-examine the alternates slice
631 and rebuild the internal bad block map accordingly. It should be
632 used whenever the alternates slice is changed by any method other
633 than the addbadsec(1M) or format(1M) utilities. DKIOCADDBAD can
634 only be used for software remapping on IDE drives; SCSI drives use
635 hardware remapping of alternate sectors.
636 DKIOCPARTINFO
639 The argument is a pointer to a part_info structure (described
641 below). This ioctl() gets the driver's notion of the size and
642 extent of the partition or slice indicated by the file descriptor
643 argument.
644 /*
646 * Used by applications to get partition or slice information
647 */
648 struct part_info {
649 daddr_t p_start;
650 int p_length;
651 };
652 DKIOCEXTPARTINFO
656 The argument is a pointer to an extpart_info structure (described
658 below). This ioctl gets the driver's notion of the size and extent
659 of the partition or slice indicated by the file descriptor argu‐
660 ment. On disks larger than 1TB, this ioctl must be used instead of
661 DKIOCPARTINFO.
662 /*
664 * Used by applications to get partition or slice information
665 */
666 struct extpart_info {
667 diskkaddr_t p_start;
668 diskaddr_t p_length;
669 };
670 DKIOCSETEXTPART
674 This ioctl is used to update the in-memory copy of the logical
676 drive information maintained by the driver. The ioctl takes no
677 arguments. It causes a re-read of the partition information and
678 recreation of minor nodes if required. Prior to updating the data
679 structures, the ioctl ensures that the partitions do not overlap.
680 Device nodes are created only for valid partition entries. If there
681 is any change in the partition offset, size or ID from the previous
682 read, the partition is deemed to have been changed and hence the
683 device nodes are recreated. Any modification to any of the logical
684 partitions results in the recreation of all logical device nodes.
685
688 addbadsec(1M), fdisk(1M), format(1M), ioctl(2), cdio(7I), cmdk(7D),
689 fdio(7I), hdio(7I), sd(7D)
690
692 Blocksize information provided in DKIOCGMEDIAINFO is the size (in
693 bytes) of the device's basic unit of operation and can differ from the
694 blocksize that the Solaris operating environment exports to the user.
695 Capacity information provided in the DKIOCGMEDIAINFO are for reference
696 only and you are advised to use the values returned by DKIOCGGEOM or
697 other appropriate ioctl for accessing data using the standard inter‐
698 faces.
699 For x86 only: If the DKIOCSMBOOT command is used to modify the Solaris
702 partitions, the VTOC information should also be set appropriately to
703 reflect the changes to partition. Failure to do so leads to unexpected
704 results when the device is closed and reopened fresh at a later time.
705 This is because a default VTOC is assumed by driver when a Solaris par‐
706 tition is changed. The default VTOC persists until the ioctl DKIOCSVTOC
707 is called to modify VTOC or the device is closed and reopened. At that
708 point, the old valid VTOC is read from the disk if it is still avail‐
709 able.
710SunOS 5.11 3 Aug 2009 dkio(7I)