Storage setup

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The storage utilized for measurements consisted of storage provided directly from a storage device for the block-based protocols and shares exported from a configured protocol server for the file-based protocols.

The same respective Logical Unit Number (LUN) is presented to either the KVM host server or the NFS/SMB protocol server.

On the server (that is, KVM host system or protocol server system) where a LUN is attached, Device Mapper Multipath (DMMP) is configured for the device. A default multipath.conf file is used with the addition of a blacklist_exceptions section as shown in Figure 1.

Figure 1. Multipath configuration file

$ cat /etc/multipath.conf
defaults {
         default_features "1 queue_if_no_path"
         user_friendly_names no
         path_grouping_policy multibus
}

blacklist {
         devnode "*"
}

blacklist_exceptions {
         devnode "^dasd[a-z]+[0-9]*"
         devnode "^sd[a-z]+[0-9]*"
}

A multipath output example is provided in Figure 2.

Figure 2. Example multipath output

$ multipath -ll
360050764008101929000000000000099 dm-1 IBM     ,2145            
size=45G features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=50 status=active
| |- 6:0:0:84          sdza  130:576  active ready running
| |- 7:0:0:84          sdzr  131:592  active ready running
| |- 9:0:0:84          sdabm 134:576  active ready running
| `- 8:0:0:84          sdabw 134:736  active ready running
`-+- policy='service-time 0' prio=10 status=enabled
  |- 3:0:0:84          sdxi  71:640   active ready running
  |- 4:0:0:84          sdxl  71:688   active ready running
  |- 2:0:0:84          sdyf  128:752  active ready running
  `- 5:0:0:84          sdxv  128:592  active ready running

Each LUN presented by the storage device is partitioned with a single partition, and then an XFS file system is created on this single partition. A QEMU raw image is created in the file system and prepared with a partition and a XFS file system prior to use by the KVM guest.