Oracle Solaris ZFS 管理指南

在存储池中指定热备件

借助热备件功能，可以在一个或多个存储池中确定能用来替换发生故障或失败的磁盘。指定一个设备作为热备件意味着该设备不是池中的活动设备，但如果池中的某一活动设备发生故障，热备件将自动替换该故障设备。

可通过以下方式将设备指定为热备件：

使用 zpool create 命令创建池时。
使用 zpool add 命令创建池之后。

以下示例说明创建池时如何将设备指定为热备件：

# zpool create trinity mirror c1t1d0 c2t1d0 spare c1t2d0 c2t2d0
# zpool status trinity
  pool: trinity
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        trinity     ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c1t1d0  ONLINE       0     0     0
            c2t1d0  ONLINE       0     0     0
        spares
          c1t2d0    AVAIL   
          c2t2d0    AVAIL   

errors: No known data errors

以下示例说明创建池之后如何通过向池中添加设备来指定热备件：

# zpool add neo spare c5t3d0 c6t3d0
# zpool status neo
  pool: neo
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        neo         ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c3t3d0  ONLINE       0     0     0
            c4t3d0  ONLINE       0     0     0
        spares
          c5t3d0    AVAIL   
          c6t3d0    AVAIL   

errors: No known data errors

可使用 zpool remove 命令从存储池中删除热备件。例如：

# zpool remove zeepool c2t3d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        zeepool     ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c1t1d0  ONLINE       0     0     0
            c2t1d0  ONLINE       0     0     0
        spares
          c1t3d0    AVAIL   

errors: No known data errors

如果存储池当前正在使用热备件，则不能将其删除。

使用 ZFS 热备件时，请考虑以下几点：

目前，zpool remove 命令只能用来删除热备件、高速缓存设备和日志设备。
要添加磁盘作为热备件，热备件的大小必须等于或大于池中最大磁盘的大小。允许向池中添加更小的磁盘作为备件。但是，当自动激活或使用 zpool replace 命令激活较小的备用磁盘时，操作将失败，并显示类似以下内容的错误：
cannot replace disk3 with disk4: device is too small

在存储池中激活和取消激活热备件

可通过以下方式激活热备件：

手动替换－通过 zpool replace 命令用热备件替换存储池中的故障设备。
自动替换－检测到故障后，FMA 代理将检查池中是否有任何可用的热备件。如果有，将使用可用备件替换故障设备。

如果当前正在使用的热备件发生故障，FMA 代理将分离该备件，从而取消替换。然后，代理将尝试用另一个热备件（如果有）替换该设备。目前，由于 ZFS 诊断引擎仅在设备从系统中消失时才会产生故障信息，因此此功能受到限制。

如果将故障设备物理替换为活动备件，则可以使用 zpool detach 命令分离该备件，从而重新激活原设备。如果将 autoreplace 池属性设置为 on，则在插入新设备并完成联机操作后，该备件会自动分离并回到备件池。

通过 zpool replace 命令可以用热备件手动替换设备。请参见示例 4–8。

如果热备件可用，将自动替换故障设备。例如：

# zpool status -x
  pool: zeepool
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
        the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
   see: http://www.sun.com/msg/ZFS-8000-2Q
 scrub: resilver completed after 0h0m with 0 errors on Mon Jan 11 10:20:35 2010
config:

        NAME          STATE     READ WRITE CKSUM
        zeepool       DEGRADED     0     0     0
          mirror-0    DEGRADED     0     0     0
            c1t2d0    ONLINE       0     0     0
            spare-1   DEGRADED     0     0     0
              c2t1d0  UNAVAIL      0     0     0  cannot open
              c2t3d0  ONLINE       0     0     0  88.5K resilvered
        spares
          c2t3d0      INUSE     currently in use

errors: No known data errors

目前，取消激活热备件的方法有以下几种：

从存储池中删除热备件。
物理替换有故障的磁盘后，分离热备件。请参见示例 4–9。
临时或永久性换入热备件。请参见示例 4–10。

示例 4–8 用热备件手动替换磁盘

本例使用 zpool replace 命令将磁盘 c2t1d0 替换为热备件 c2t3d0。

# zpool replace zeepool c2t1d0 c2t3d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Wed Jan 20 10:00:50 2010
config:

        NAME          STATE     READ WRITE CKSUM
        zeepool       ONLINE       0     0     0
          mirror-0    ONLINE       0     0     0
            c1t2d0    ONLINE       0     0     0
            spare-1   ONLINE       0     0     0
              c2t1d0  ONLINE       0     0     0
              c2t3d0  ONLINE       0     0     0  90K resilvered
        spares
          c2t3d0      INUSE     currently in use

errors: No known data errors

然后分离磁盘 c2t1d0。

# zpool detach zeepool c2t1d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Wed Jan 20 10:00:50 2010
config:

        NAME        STATE     READ WRITE CKSUM
        zeepool     ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c1t2d0  ONLINE       0     0     0
            c2t3d0  ONLINE       0     0     0  90K resilvered

errors: No known data errors

示例 4–9 替换故障磁盘后分离热备件

本例使用 zpool replace 命令物理替换磁盘 (c2t1d0) 并通知 ZFS。

# zpool replace zeepool c2t1d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Wed Jan 20 10:08:44 2010
config:

        NAME          STATE     READ WRITE CKSUM
        zeepool       ONLINE       0     0     0
          mirror-0    ONLINE       0     0     0
            c1t2d0    ONLINE       0     0     0
            spare-1   ONLINE       0     0     0
              c2t3d0  ONLINE       0     0     0  90K resilvered
              c2t1d0  ONLINE       0     0     0
        spares
          c2t3d0      INUSE     currently in use

errors: No known data errors

然后，您可以使用 zpool detach 命令使热备件回到备件池。例如：

# zpool detach zeepool c2t3d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed with 0 errors on Wed Jan 20 10:08:44 2010
config:

        NAME               STATE     READ WRITE CKSUM
        zeepool            ONLINE       0     0     0
          mirror           ONLINE       0     0     0
            c1t2d0         ONLINE       0     0     0
            c2t1d0         ONLINE       0     0     0
        spares
          c2t3d0           AVAIL

errors: No known data errors

示例 4–10 分离故障磁盘并使用热备件

如果想临时或永久性换入用于替换的热备件，以此替换故障磁盘，则应分离原（故障）磁盘。故障磁盘完成替换后，可以将其再添加到存储池用作备件。例如：

# zpool status zeepool
  pool: zeepool
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
        the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
   see: http://www.sun.com/msg/ZFS-8000-2Q
 scrub: resilver in progress for 0h0m, 70.47% done, 0h0m to go
config:

        NAME          STATE     READ WRITE CKSUM
        zeepool       DEGRADED     0     0     0
          mirror-0    DEGRADED     0     0     0
            c1t2d0    ONLINE       0     0     0
            spare-1   DEGRADED     0     0     0
              c2t1d0  UNAVAIL      0     0     0  cannot open
              c2t3d0  ONLINE       0     0     0  70.5M resilvered
        spares
          c2t3d0      INUSE     currently in use

errors: No known data errors
# zpool detach zeepool c2t1d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Wed Jan 20 13:46:46 2010
config:

        NAME        STATE     READ WRITE CKSUM
        zeepool     ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c1t2d0  ONLINE       0     0     0
            c2t3d0  ONLINE       0     0     0  70.5M resilvered

errors: No known data errors
(Original failed disk c2t1d0 is physically replaced)
# zpool add zeepool spare c2t1d0
# zpool status zeepool
  pool: zeepool
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Wed Jan 20 13:48:46 2010
config:

        NAME        STATE     READ WRITE CKSUM
        zeepool     ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            c1t2d0  ONLINE       0     0     0
            c2t3d0  ONLINE       0     0     0  70.5M resilvered
        spares
          c2t1d0    AVAIL   

errors: No known data errors