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authorHeiko Carstens <heiko.carstens@de.ibm.com>2019-07-25 03:21:47 -0400
committerVasily Gorbik <gor@linux.ibm.com>2019-08-21 06:41:42 -0400
commit8c72e0c85212df4e7c77fca55556e423fe17e801 (patch)
tree26fedaa9d519634d95ae58e7dc9b2f3bcdfde6ed
parent7c4e91c0959bf42a86ba4887425fc944d0d28595 (diff)
Documentation/s390: remove outdated dasd documentation
The contents of the file is completely outdated - just remove it. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
-rw-r--r--Documentation/s390/dasd.rst84
-rw-r--r--Documentation/s390/index.rst1
2 files changed, 0 insertions, 85 deletions
diff --git a/Documentation/s390/dasd.rst b/Documentation/s390/dasd.rst
deleted file mode 100644
index 9e22247285c8..000000000000
--- a/Documentation/s390/dasd.rst
+++ /dev/null
@@ -1,84 +0,0 @@
1==================
2DASD device driver
3==================
4
5S/390's disk devices (DASDs) are managed by Linux via the DASD device
6driver. It is valid for all types of DASDs and represents them to
7Linux as block devices, namely "dd". Currently the DASD driver uses a
8single major number (254) and 4 minor numbers per volume (1 for the
9physical volume and 3 for partitions). With respect to partitions see
10below. Thus you may have up to 64 DASD devices in your system.
11
12The kernel parameter 'dasd=from-to,...' may be issued arbitrary times
13in the kernel's parameter line or not at all. The 'from' and 'to'
14parameters are to be given in hexadecimal notation without a leading
150x.
16If you supply kernel parameters the different instances are processed
17in order of appearance and a minor number is reserved for any device
18covered by the supplied range up to 64 volumes. Additional DASDs are
19ignored. If you do not supply the 'dasd=' kernel parameter at all, the
20DASD driver registers all supported DASDs of your system to a minor
21number in ascending order of the subchannel number.
22
23The driver currently supports ECKD-devices and there are stubs for
24support of the FBA and CKD architectures. For the FBA architecture
25only some smart data structures are missing to make the support
26complete.
27We performed our testing on 3380 and 3390 type disks of different
28sizes, under VM and on the bare hardware (LPAR), using internal disks
29of the multiprise as well as a RAMAC virtual array. Disks exported by
30an Enterprise Storage Server (Seascape) should work fine as well.
31
32We currently implement one partition per volume, which is the whole
33volume, skipping the first blocks up to the volume label. These are
34reserved for IPL records and IBM's volume label to assure
35accessibility of the DASD from other OSs. In a later stage we will
36provide support of partitions, maybe VTOC oriented or using a kind of
37partition table in the label record.
38
39Usage
40=====
41
42-Low-level format (?CKD only)
43For using an ECKD-DASD as a Linux harddisk you have to low-level
44format the tracks by issuing the BLKDASDFORMAT-ioctl on that
45device. This will erase any data on that volume including IBM volume
46labels, VTOCs etc. The ioctl may take a `struct format_data *` or
47'NULL' as an argument::
48
49 typedef struct {
50 int start_unit;
51 int stop_unit;
52 int blksize;
53 } format_data_t;
54
55When a NULL argument is passed to the BLKDASDFORMAT ioctl the whole
56disk is formatted to a blocksize of 1024 bytes. Otherwise start_unit
57and stop_unit are the first and last track to be formatted. If
58stop_unit is -1 it implies that the DASD is formatted from start_unit
59up to the last track. blksize can be any power of two between 512 and
604096. We recommend no blksize lower than 1024 because the ext2fs uses
611kB blocks anyway and you gain approx. 50% of capacity increasing your
62blksize from 512 byte to 1kB.
63
64Make a filesystem
65=================
66
67Then you can mk??fs the filesystem of your choice on that volume or
68partition. For reasons of sanity you should build your filesystem on
69the partition /dev/dd?1 instead of the whole volume. You only lose 3kB
70but may be sure that you can reuse your data after introduction of a
71real partition table.
72
73Bugs
74====
75
76- Performance sometimes is rather low because we don't fully exploit clustering
77
78TODO-List
79=========
80
81- Add IBM'S Disk layout to genhd
82- Enhance driver to use more than one major number
83- Enable usage as a module
84- Support Cache fast write and DASD fast write (ECKD)
diff --git a/Documentation/s390/index.rst b/Documentation/s390/index.rst
index 4602312909d3..f8c01cb7fa37 100644
--- a/Documentation/s390/index.rst
+++ b/Documentation/s390/index.rst
@@ -15,7 +15,6 @@ s390 Architecture
15 vfio-ap 15 vfio-ap
16 vfio-ccw 16 vfio-ccw
17 zfcpdump 17 zfcpdump
18 dasd
19 common_io 18 common_io
20 19
21 text_files 20 text_files