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--- howto:use_ldann_logical_disks [2018/10/23 22:30] – add some subheaders lricker
+++ howto:use_ldann_logical_disks [2018/10/23 22:38] – tweaks lricker
@@ Line 89: / Line 89: @@
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-This just creates a big file, with no actual contents other than whatever “junk data” was previously in the disk blocks allocated to this file.  Note that, although we've used .DSK as the file extension in this example, you can use whatever file extension you like, as there's no specific file-type enforced... However, stick to a filename and type that is conventional and “obvious.”
+This just creates a big file, with no actual contents other than whatever “junk data” was previously in the disk blocks allocated to this file.  Note that, although we've used .DSK as the file extension in this example, you can use whatever file extension you like, as there's no specific file-type enforced.  However, stick to a filename and type that is conventional and “obvious.”
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-On our CLASS8 training system here at PARSEC, we play with numerous Logical Disks, so we've got lots.  Your mileage will vary, and to begin with, you'll likely show no ''LDAnnn:'' devices on your system... This will be your first.  On a system with existing ''LDAnnn:'' devices, pick a totally new, unused unit number.
+On our CLASS8 training system here at PARSEC, we play with numerous Logical Disks, so we've got lots.  Your mileage will vary, and to begin with, you'll likely show no ''LDAnnn:'' devices on your system -- this will be your first.  On a system with existing ''LDAnnn:'' devices, pick a totally new, unused unit number.
-Because it's easy(er) to remember and type, let's use ''LDA77:'' for our experiments.  This will likely be a temporary use for this particular unit number ― if you ever decide to “go to production” or other regular, persistent use for a particular Logical Disk, be sure to more-or-less permanently allocate an ''LDAxxx:'' (unit number) to that LD-file; likely, you'll put all of that into a startup command file for consistency.
+Because it's easy(er) to remember and type, let's use ''LDA77:'' for our experiments.  This will likely be a temporary use for this particular unit number -- if you ever decide to “go to production” or other regular, persistent use for a particular Logical Disk, be sure to more-or-less permanently allocate an ''LDAxxx:'' (unit number) to that LD-file; likely, you'll put all of that into a startup command file for consistency.
   $ LD CONNECT /LOG DSA2:[LRICKER]SANDBOX.DSK LDA77: LDISK$SANDBOX
   %LD-I-CONNECTED, Connected $254$LDA77: to DSA2:[LRICKER]SANDBOX.DSK;1
-We're making consistent use of the ''/LOG'' qualifier for these LD-commands just to show what‟s happening... this qualifier is optional.
+We're making consistent use of the ''/LOG'' qualifier for these LD-commands just to show what's happening... this qualifier is optional.
-Note: Experience shows that the LD ''CREATE'' and ''CONNECT'' (and, by extension, the ''DISCONNECT'') commands are particular, picky even, about the colon “:” on the end of the LDAxxx: device name ― Don't omit that colon!
+Note: Experience shows that the LD ''CREATE'' and ''CONNECT'' (and, by extension, the ''DISCONNECT'') commands are particular, picky even, about the colon “:” on the end of the LDAxxx: device name -- Don't omit that colon!
-Now, ''LDA77:'' is a device that just happens to be “backed by” (or implemented as) a file. Since this file has just been created, it has no valid contents ― and certainly does notyet have a file system in it.  So this:
+Now, ''LDA77:'' is a device that just happens to be “backed by” (or implemented as) a file. Since this file has just been created, it has no valid contents -- and certainly does not yet have a file system in it.  So this:
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 ==== Initializing Your LDAnnn: Disk ====
-We do this next command ― not surprisingly, an INITIALIZE command ― once (per newly-created LD-device)... Note that this command does not initialize the file, it initialized the __device__.  Whenever we __create__ a new LD-container file and __connect__ it, we need to next initialize its file system (contents). Be sure to give the file system a meaningful volume label; you can choose //either// a Files-11 ODS-2 (default, or ''/STRUCTURE=2'') or ODS-5 (extended file system, ''/STRUCTURE=5'') file system:
+We do this next command -- not surprisingly, an INITIALIZE command -- once (per newly-created LD-device)... Note that this command does not initialize the file, it initialized the __device__.  Whenever we __create__ a new LD-container file and __connect__ it, we need to next initialize its file system (contents). Be sure to give the file system a meaningful volume label; you can choose //either// a Files-11 ODS-2 (default, or ''/STRUCTURE=2'') or ODS-5 (extended file system, ''/STRUCTURE=5'') file system:
   $ INITIALIZE /STRUCTURE=5 LDA77: SANDBOX
@@ Line 250: / Line 250: @@
 because that previous ''INITIALIZE'' command did not use the ''/SYSTEM'' qualifier, this LD-volume is owned by the __user__, not by ''[SYSTEM]'' (or ''[1,4]''). This may or may not be a problem for a particular use case, so just be aware of the options involved here, just like for any other disk/device/volume.
-Let's use this new volume ― exercise it with a few file commands:
+Let's use this new volume -- exercise it with a few file commands:
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-Dismounting an LD-disk is just dismounting a disk device. Read about the LD ''DISCONNECT /ABORT'' qualifier ― usually unneeded, unless there are pesky multi-user connections that won't “let go”.  The ''DELETE'' command makes the sandbox file good and truly gone. But easily recreated...
+Dismounting an LD-disk is just dismounting a disk device. Read about the LD ''DISCONNECT /ABORT'' qualifier -- usually unneeded, unless there are pesky multi-user connections that won't “let go”.  The ''DELETE'' command makes the sandbox file good and truly gone. But easily recreated...
 ==== Summary of Use Cases ====
-To summarize ― Logical Disks are good for:
+To summarize -- Logical Disks are good for:
-  * Practicing VMS file commands, etc. ― As a learning tool, having one or more sandbox disks available for users (and yourself) to practice in makes it easy and stress-free to learn (“No, you can‟t break anything... play to your heart's content...”).
+  * Practicing VMS file commands, etc. -- As a learning tool, having one or more sandbox disks available for users (and yourself) to practice in makes it easy and stress-free to learn (“No, you can‟t break anything... play to your heart's content...”).
-  * Containers for isolation, development and testing ― Need an ODS-5 disk structure without changing the underlying host-ODS-2 disk (or visa versa)?  Create a logical disk with the target file system structure.
+  * Containers for isolation, development and testing -- Need an ODS-5 disk structure without changing the underlying host-ODS-2 disk (or visa versa)?  Create a logical disk with the target file system structure.
   * Containers for installing a layered product or complete application suite into... without disrupting production use of the real/released-version of that software package. Do you see how the principles of rapid deployment might benefit from this tool/resource?
+  * Providing very-fine-grained security protection (protection masks, ACLs) both to the LD-container file itself, and to any/all files it contains.
   * Any other purpose where containers can be used to isolate, enclose and protect packages of software, project use, or other special-purpose scenarios.