操作環境

OS

CentOS Linux release 7.4.1708 (Core)
Linux centos7-nfstest 3.16.55 #1 SMP Sun Mar 4 23:15:32 EST 2018 x86_64 x86_64 x86_64 GNU/Linux

tgt

[[email protected] ~]# tgtadm --version
1.0.55

操作步驟

配置tgtd支援thin provision，tgtd後端必須使用檔案系統型別，不能是硬碟。並且檔案系統必須支援FALLOC_FL_PUNCH_HOLE，下面是支援FALLOC_FL_PUNCH_HOLE的檔案系統

  Not all filesystems support FALLOC_FL_PUNCH_HOLE; if a filesystem
       doesn't support the operation, an error is returned.  The operation
       is supported on at least the following filesystems:

       *  XFS (since Linux 2.6.38)

       *  ext4 (since Linux 3.0)

       *  Btrfs (since Linux 3.7)

       *  tmpfs(5) (since Linux 3.5)
 

本次實驗採用的xfs檔案系統。

1.安裝tgtd

[[email protected] ~]# yum -y install scsi-target-utils

2.建立backstore檔案，該檔案儲存在支援xfs檔案系統的裝置上。

[[email protected] ~]# tgtimg --op new --device-type disk --type disk --size 5120m --file /mnt/big_disc_file1.tgt

3.修改tgtd配置檔案

[[email protected] ~]# vi /etc/tgt/targets.conf 
# This is a sample config file for tgt-admin.
#
# The "#" symbol disables the processing of a line.

# Set the driver. If not specified, defaults to "iscsi".
default-driver iscsi

# Set iSNS parameters, if needed
#iSNSServerIP 192.168.111.222
#iSNSServerPort 3205
#iSNSAccessControl On
#iSNS On

# Continue if tgtadm exits with non-zero code (equivalent of
# --ignore-errors command line option)
ignore-errors yes
include /etc/tgt/conf.d/*.conf
 

4.在tgt的conf.d目錄下，修改sample.conf檔案，也可自行建立新conf檔案

<target iqn.2008-09.com.example:server.target1>
    backing-store /mnt/big_disc_file1.tgt
    verdor_id BobMake
</target>

5.檢視tgt資訊，此次我們檢視tgt資訊中Thin-provisioning選項為No狀態

[[email protected] ~]# tgtadm --mode target --op show
Target 1: iqn.2008-09.com.example:server.target1
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
        LUN: 1
            Type: disk
            SCSI ID: IET     00010001
            SCSI SN: beaf11
            Size: 5369 MB, Block size: 512
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: rdwr
            Backing store path: /mnt/big_disc_file1.tgt
            Backing store flags: 
    Account information:
    ACL information:
        ALL
 

6.配置tgtd支援Thin-Provisioning

[[email protected] ~]# tgtadm --lld iscsi --mode logicalunit --op update --tid 1 --lun 0 --params thin_provisioning=1
[[email protected] ~]# tgtadm --lld iscsi --mode logicalunit --op update --tid 1 --lun 1 --params thin_provisioning=1

再次檢視tgt資訊，Thin-provisionging為Yes狀態

[[email protected] ~]# tgtadm --mode target --op show
Target 1: iqn.2008-09.com.example:server.target1
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: Yes
            Backing store type: null
            Backing store path: None
            Backing store flags: 
        LUN: 1
            Type: disk
            SCSI ID: IET     00010001
            SCSI SN: beaf11
            Size: 5369 MB, Block size: 512
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: Yes
            Backing store type: rdwr
            Backing store path: /mnt/big_disc_file1.tgt
            Backing store flags: 
    Account information:
    ACL information:
        ALL

很奇怪在這裡必須用命令列才能配置tgtd支援thin-provisioning，在配置檔案裡面新增thin-provisioning如下，tgt資訊裡面thin-provisioning仍然顯示No狀態

<target iqn.2008-09.com.example:server.target1>
    backing-store /mnt/big_disc_file1.tgt
    verdor_id BobMake
    thin_provisioning 1
</target>

7.從客戶端連線該tgt，並檢視是否支援thin-provisioning

[[email protected] ~]# sg_vpd -p 0xb2 /dev/sdg
Logical block provisioning VPD page (SBC):
  Unmap command supported (LBPU): 1
  Write same (16) with unmap bit supported (LBWS): 1
  Write same (10) with unmap bit supported (LBWS10): 1
  Logical block provisioning read zeros (LBPRZ): 1
  Anchored LBAs supported (ANC_SUP): 0
  Threshold exponent: 0
  Descriptor present (DP): 0
  Provisioning type: 2

注意unmap command supportd值為1。

8.測試scsi unmap命令

在iscsi客戶端向sdg（iscsi target裝置）寫入資料塊

[[email protected] ~]# dd if=/dev/zero of=/dev/sdg bs=512 seek=1024 count=128
128+0 records in
128+0 records out
65536 bytes (66 kB) copied, 0.014353 s, 4.6 MB/s

檢驗塊是否對映

[[email protected] ~]# sg_get_lba_status -l 1024 /dev/sdg
descriptor LBA: 0x0000000000000400  blocks: 128  mapped

取消對映塊，這裡我們取消16個對映塊

[[email protected] ~]# sg_unmap -v -l 1024 -n 16 /dev/sdg
    unmap cdb: 42 00 00 00 00 00 00 00 18 00 

檢驗unmap是否執行

檢視是否已取消對映塊

[[email protected] ~]# sg_get_lba_status -l 1024 /dev/sdg
descriptor LBA: 0x0000000000000400  blocks: 16  deallocated

檢視之後未取消的對映塊

[[email protected] ~]# sg_get_lba_status -l 1040 /dev/sdg
descriptor LBA: 0x0000000000000410  blocks: 112  mapped