Talk:LPIC-2 Objectives V4

Anonymous: Notes: on Device Mapper coverage

Based on reading through the current [1] and Wiki [2] developments, I have the following recommendation.

- Create a new, separate Objective in Section 204
- Suggested "Section 204.4 Device Mapper" follows [A]
- From other 204 Sections ...
  - Remove Device Mapper (e.g., /dev/mapper)
  - Remove WWID/WWN and SCSI ID (e.g., scsi_id)
  - NOTE:  Do not remove iSCSI** (although may belong in another section) 

• • NOTE: Given the details involved with iSCSI initiator (client), among other options, consider moving iSCSI initator (plus any other "network storage client" boot/config/init) to its own, separate Section 204 (204.5?). This e-mail only covers Device Mapper and its facilities, which I suggest for Section 204.4.

[1] http://www.lpi.org/linux-certifications/programs/lpic-2/exam-201/#section-203 [2] http://wiki.lpi.org/wiki/LPIC-2_Objectives#Topic_203:_Filesystem_and_Devices

[A] Objective "Suggestion" w/extra detail (beyond what would be published)

Objective 204.4 Device Mapper

Weight: 1 (as 204.2 Today) or 2 (as 204.2 Wiki/Future)

 NOTE:  1-2 is _less_ than other 204 Sections

Description: Candidates should be able to use DeviceMapper facilities and userspace to identify, filter, blacklist, whitelist and resolve presentation of block devices, including for virtualization guests, LVM mappings, multitarget mappings (SCSI/SAS) and multipath mappings (FC/SAN).

 NOTE:  This section is _not_ for things done with udev, but _only_ DeviceMapper-specific facilities and userspace.

- Command:  dmsetup
  E.g., dmsetup [info|ls]

- Command:  scsi_id
  E.g., scsi_id --page=0x8[0|3] --device=(device)

- Path(s):  /dev/disk/by-[id|label|path|uuid]/
  These should be self-explanatory ;)

- Path(s):  /dev/mapper/
  Moved from LVM Section, which is more for LVM operations

- Path(s):  /sys/block/
  Block device paths -- e.g., often symlinks to /sys/devices

- Path(s):  /sys/devices/
  Device bus/host/lun paths -- e.g., Bus/HBA as well as c:t:d:s

- Config*:  lvm.conf
  Limited to:  volume_list, filter, issue_discards

- Config*:  multipath.conf
  Limited to:  wwid and alias only

- Runtime:  /var/lib/multipath/bindings
  Limited to:  wwid-only

• lvm.conf _limited_ to:

- Section "activation" (VG/LV activation options)
  - Option "volume_list" (VG implicit whitelist)
- Section "device" (PV/device options)
  - Option "filter" (device blacklist and/or whitelist)
  - Option "issue_discards" (NAND EEPROM SSD lifespan/perf)
  - Option "preferred_names" (path order of preference)

LVM NOTE: Remember, "volume_list" and/or "filter" is often used to ensure virtualization hosts do _not_ access Physical Volumes (and active Volume Groups) for their virtualization guests.

• multipath.conf _limited_ to:

- Section "blacklist" (blacklist)
  - Option "wwid" (blacklist)
- Section "multipaths / multipath" (whitelist/alias in stanza) 
  - Option "wwid" (whitelist)
  - Option "alias" (label)

LVM NOTE: It's also important to "filter" Devices so they are only found on select devices for multitarget (SCSI/SAS) and multipath (FC/SAN).

213/214.4 Predict Future Resource Needs

Could anyone give good source to prepare courses for this topic? I could not for myself.

If this is too tricky to find source, i think we should avoid the topic.

--EricDeschamps 11:04, 5 April 2013 (EDT)