Red Hat LINUX VIRTUAL SERVER 4.7 - ADMINISTRATION Guida di Installazione

LandmannRed Hat Enterprise Linux 4DM MultipathDM Multipath Configuration and AdministrationEdition 1.0

static int kvm_vm_ioctl_deassign_device(struct kvm *kvm, struct kvm_assigned_pci_dev * assigned_dev){ int r = 0; struc

Chapter 1. Device Mapper MultipathingDevice Mapper Multipathing (DM-Multipath) allows you to configure multiple I/O paths between servernodes and stor

Array controller port failureWith DM-Multipath configured, a failure at any of these points will cause DM-Multipath to switch to thealternate I/O path

Figure 1.3. Act ive/Active Multipath Configuration with One RAID Device1.2. Storage Array SupportBy default, DM-Multipath includes support for the mos

Table 1.1. DM-Multipath Component sComponent Descriptiondm -multipath kernel module Reroutes I/O and supports failover for paths and path groups.m ult

Chapter 2. Multipath DevicesWithout DM-Multipath, each path from a server node to a storage controller is treated by the system as aseparate device, e

If you want the system-defined user-friendly names to be consistent across all nodes in the cluster,set up all of the multipath devices on one machine

Chapter 3. Setting Up DM-MultipathThis chapter provides step-by-step example procedures for configuring DM-Multipath. It includes thefollowing procedu

If the SCSI devices do not appear, ensure that all SAN connections are set up properly.For further information on the m ultipath command and its outpu

[root@rh4cluster1 ~]# multipath -v2create: SIBM-ESXSST336732LC____F3ET0EP0Q000072428BX1[size=33 GB][features="0"][hwhandler="0"]\_

Red Hat Enterprise Linux 4 DM MultipathDM Multipath Configuration and AdministrationEdition [email protected] m

[root@rh4cluster1 ~]# multipath -F[root@rh4cluster1 ~]# multipath -v2create: 3600a0b80001327d80000006d43621677[size=12 GB][features="0"][hwh

Chapter 4. The DM-Multipath Configuration FileBy default, DM-Multipath provides configuration values for the most common uses of multipathing. Inaddit

devicesSettings for the individual storage controllers. T hese values overwrite what is specified in the defaults section of the configuration file. I

devnode_blacklist { devnode "^sd[a-z]"}You can use a devnode entry in the blacklist section of the configuration file to specify indiv

defaults { user_friendly_names yes path_grouping_policy m ultibus}Table 4.1, “Multipath Configuration Defaults” describes the att

Table 4 .1. Multipath Configuration Default sAttribute Description udev_dir Specifies the directory where udev device nodes are created. T hedefault

rr_min_io Specifies the number of I/O requests to route to a path beforeswitching to the next path in the current path group. The defaultvalue is 10

4.4. Multipaths Device Configuration AttributesTable 4.2, “Multipath Attributes” shows the attributes that you can set in the m ultipaths section of t

Table 4 .2. Multipath Attribut esAttribute Description wwid Specifies the WWID of the multipath device to which the m ultipath attributes apply. alia

flush_on_last_del (RHEL 4.7 and later) If set to yes, the m ultipathd daemon willdisable queueing when the last path to a device has been deleted.Th

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need to set the vendor and product parameters. You can find these values by looking at /sys/block/device_name/device/vendor and /sys/block/device_name

Table 4 .3. Device AttributesAttribute Description vendor Specifies the vendor name of the storage device to which the device attributes apply, for e

group. T he default value is 1000. rr_weight If set to priorities, then instead of sending rr_min_iorequests to a path before calling selector to cho

Chapter 5. DM-Multipath Administration and TroubleshootingThis chapter will provide information on administering DM-Multipath on a running system. It

NoteWhen a multipath device is being created or modified, the path group status and the dm statusare not known. Also, the features are not always corr

The following command displays all the device mapper devices and their major and minor numbers. T heminor numbers determine the name of the dm device.

Use the following procedure to resize an online multipath device.1. Resize your physical device.2. Resize your paths. For SCSI devices, writing a 1

Revision HistoryRevision 1.0-11.4 00 2013- 10-31 Rüdiger LandmannRebuild with publican 4.0.0Revision 1.0-11 2012-07-18 Anthony TownsRebuild for Public

- blacklist, Setting Up DM-Multipath, Configuration File Blacklist- bl_product parameter, Configuration File Devices- devnode_blacklist, Configuration

devices section- multipath.conf file, Configuration File Devicesdevnode_blacklist- configuration file, Configuration File BlacklistDM-Multipath- and L

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kpart x command , DM-Multipath ComponentsLlocal disks, ignoring, Ignoring Local Disks when Generating Mult ipath DevicesLVM physical volumes- multipat

Ppath_checker parameter, Configuration File Default s, Configuration File Devicespath_grouping_policy parameter, Configuration File Default s, Multipa

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Table of Contents 3

PrefaceThis book describes the Device Mapper Multipath (DM-Multipath) feature of Red Hat Enterprise Linux.1. AudienceThis book is intended to be used

Be sure to mention the manual's identifier:rh-MPIO(EN)-4.9 (2011-02-16T16:48)By mentioning this manual's identifier, we know exactly which v

labeled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example:Choose System → Preferences → Mouse from the main men