BTW, I want to hammer one point home ... If you have _ever_ wondered why you get the message "duplicate PV" from LVM ... now you know. Just because you don't see DeviceMapper doesn't mean it doesn't need specific configurations.
Hence why I included things like "dmsetup info" and "dmsetup ls" as well as the LVM activate/filter and other things. I spend a _lot_ of time "cleaning up messes" from sysadmins who don't understand why such filtering is _required_. ;) -- bjs P.S. We should probably consider including the "kpartx" command in this Section as well, as it's tied to DeviceMapper. On Sat, Jun 15, 2013 at 1:31 AM, Bryan J Smith <[email protected]> wrote: > Per my prior e-mails and offering ... > > 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) > > -- bjs > > **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). > > > -- > Bryan J Smith - Professional, Technical Annoyance > b.j.smith at ieee.org - http://www.linkedin.com/in/bjsmith > > -- -- Bryan J Smith - Professional, Technical Annoyance b.j.smith at ieee.org - http://www.linkedin.com/in/bjsmith
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