Bug 142263
Summary: | Only 16 EMC powerpath LUNs usable with LVM1 | ||||||||
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Product: | Red Hat Enterprise Linux 3 | Reporter: | Thomas Uebermeier <uthomas> | ||||||
Component: | lvm | Assignee: | Doug Ledford <dledford> | ||||||
Status: | CLOSED ERRATA | QA Contact: | Brian Brock <bbrock> | ||||||
Severity: | medium | Docs Contact: | |||||||
Priority: | medium | ||||||||
Version: | 3.0 | CC: | agk, coughlan, hgarcia, jrfuller, kanderso, peterm, petrides, poelstra, tao | ||||||
Target Milestone: | --- | ||||||||
Target Release: | --- | ||||||||
Hardware: | i686 | ||||||||
OS: | Linux | ||||||||
Whiteboard: | |||||||||
Fixed In Version: | RHSA-2005-663 | Doc Type: | Bug Fix | ||||||
Doc Text: | Story Points: | --- | |||||||
Clone Of: | Environment: | ||||||||
Last Closed: | 2005-09-28 14:34:44 UTC | Type: | --- | ||||||
Regression: | --- | Mount Type: | --- | ||||||
Documentation: | --- | CRM: | |||||||
Verified Versions: | Category: | --- | |||||||
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
Cloudforms Team: | --- | Target Upstream Version: | |||||||
Embargoed: | |||||||||
Bug Depends On: | |||||||||
Bug Blocks: | 156320 | ||||||||
Attachments: |
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Description
Thomas Uebermeier
2004-12-08 17:19:29 UTC
Thomas, I need to add a filter to the device discovery code in LVM1 in order to avoid access to the 'raw' devices in case PowerPath ones give access. The other issue about limited number of devices (16) needs tweeking in the same discovery code. Hopefully will get around to this before Christmas ;) Still no PowerPath copy here to be able to test myself (EMC claims they are pushing delivery). I'll push any fixes to you to test on the Bladecenter configuration first. Heinz, I just received some more informations from the customer, from which I would say, to put the "max 16 devices" issue to a hold, the devices do *not* show up in /proc/partitions, sorry for the confusion... The emcpower*/sd* device thing is still left (and much more nasty), shall I create a new bug for that, so we can track it separately ? Thomas, in lieu of the PowerPath /proc/partitions bug, yes please create a new bug in order to track the /dev/sd* filter issue seperately from this one. Background on the 16 max limit issue: ----- Forwarded message from "goggin, edward" <egoggin> ----- Assuming this is a 2.4 kernel ... the 16 device limit likely applies to emcpower whole device names which show up in /proc/partitions. Only 16 emcpower whole device names show up in this file due to the code in disk_name() in fs/partitions/check.c which both (1) enforces a very simplistic naming policy on all devices which are not (scsi,ide, and a few privileged others) and (2) assumes a driver can only manage a single major number. This single major number requirement is not met by the PowerPath driver since like the scsi class driver, it manages 16 major numbers. Given enough LUNs in your SAN, you will see the device name sequence (emcpowera, ... , emcpowerp) repeated multiple times in /proc/partitions, each time with a different major number, from 247-232 inclusive. Sixteen show up for each major number since, like scsi, PowerPath's dev_t uses 4 minor bits for indicating partition so there are but 4 bits left in each 8-bit minor to specify whole device instance. This is all done better in the 2.6 kernel since each driver is allowed to determine the name of the devices the driver manages and record the name in the gendisk entry (which is per minor not per major) for each device. SuSE has addressed this problem in its 2.4 based SLES 8 distribution by introducing a "driver name" callout in the per-major gendisk structure and calling this callout in disk_name(). We have been aware of this issue for over 2 1/2 years and have made Red Hat aware of the issue for that same length of time. My suspicion has been that due to Red Hat's goal to provide backward compatibility for kernel modules in its 2.4 based enterprise distributions, it was more difficult to fix this issue. Created attachment 108192 [details]
/proc/partitions
ok, that makes sense now. Isn't quite nice (the device naming from EMC admin
tools (you can get emcpowerq and above) compared to /proc/partitions))
though...
Is there any chance of ever getting this fixed within RHEL3 ?
Followup Bug for device filtering: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=142386 PM ACK for U6 *** This bug has been marked as a duplicate of 79086 *** A fix for this problem has just been committed to the RHEL3 U6 patch pool this evening (in kernel version 2.4.21-34.EL). Propagating acks from bug 79086. An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2005-663.html |