Tagged: tips

Fix “Find My Mac” not available problem


更新了 10.7.2 發現”Find My Mac”不能使用. 我重新安裝 Lion重新升級到 10.7.2 也是不行. 最後爬文爬到“Find My Mac” not available after Lion Recovery Update and 10.7.2 Update, “Find My Mac” not available after Lion Recovery Update and 10.7.2 Update 終於搞定. 下列是解決方法 :

1. 將電腦關機. 進入修復模式 (Recovery Mode). 按著 command + R, 然後開機.
2. 使用”Disk Utility” 進行 驗證磁碟(Verify Disk), 理論上會出現錯誤. 然後再修復磁碟(Repair Disk). 修好了之後重新開機
3. 重新安裝 Recovery HD Update. 到 RecoveryHDUpdate.dmg 下載. 安裝好了之後就修復了.


修復完成圖~ :D

ethX 辨識

在linux底下的 ethX 常常與主機板編號的順序不太一樣.

所以得用下列指令辨識哪個孔是哪個 ethX

# ethtool -p ethX
# ethtool --identify ethX

xfs error : “mount: Structure needs cleaning”

當我在掛載 xfs partition 時出現了”Structure needs cleaning”錯誤

# mount /dev/sdb1 /disk2
mount: Structure needs cleaning

我用了下列的指令解決了. 雖然我不太清楚什麼東西導致它有問題 :
# xfs_repair -n /dev/sdb1

上面指令還不能完全解決

# xfs_check /dev/sdb1
ERROR: The filesystem has valuable metadata changes in a log which needs to
be replayed. Mount the filesystem to replay the log, and unmount it before
re-running xfs_check. If you are unable to mount the filesystem, then use
the xfs_repair -L option to destroy the log and attempt a repair.
Note that destroying the log may cause corruption — please attempt a mount
of the filesystem before doing this.

用 xfs_check 指令. 它建議我用 “xfs_repair -L ”
# xfs_repair -L /dev/sdb1

這樣弄玩之後. 在用 xfs_check 檢查一次
# xfs_check /dev/sdb1

就可以掛載了
# mount /dev/sdb1 /disk2

在蘋果用命令掛載 .dmg 並遠端安裝 .pkg

在遠端管理mac的時候就需要這樣的技巧.

第一個步驟. 要先知道如何掛載 dmg 映像檔.
# hdiutil attach foo.dmg

Checksumming Driver Descriptor Map (DDM : 0)…
Driver Descriptor Map (DDM : 0): verified CRC32 $FEF30ABC
Checksumming (Apple_Free : 1)…
(Apple_Free : 1): verified CRC32 $00000000
Checksumming Apple (Apple_partition_map : 2)…
Apple (Apple_partition_map : 2): verified CRC32 $759BB202
Checksumming Macintosh (Apple_Driver_ATAPI : 3)…
Macintosh (Apple_Driver_ATAPI : 3): verified CRC32 $F1E8BA9E
Checksumming (Apple_Free : 4)…
(Apple_Free : 4): verified CRC32 $00000000
Checksumming disk image (Apple_HFS : 5)…
………………………………………………………………
disk image (Apple_HFS : 5): verified CRC32 $02C572A3
Checksumming (Apple_Free : 6)…
(Apple_Free : 6): verified CRC32 $00000000
verified CRC32 $31655A51
/dev/disk1 Apple_partition_scheme
/dev/disk1s1 Apple_partition_map
/dev/disk1s2 Apple_Driver_ATAPI
/dev/disk1s3 Apple_HFS /Volumes/foo Update

第二個步驟, 用 installer 指令安裝 . pkg 檔案
# sudo installer -pkg /Volumes/foo/bar.pkg -target “/”

installer: Package name is foo-bar
installer: Upgrading at base path /
installer: The upgrade was successful.

最後個步驟就是, 反掛載 .dmg 檔案
# hdiutil detach /Volumes/foo/

“disk1″ unmounted.
“disk1″ ejected.

如此一來就可以偷偷幫使用者背景更新程式. 不為人知..搞得好像行善不為人知. Orz

Linux 開關 swap partitions 

# swapon –a

打開所有 swap partitions

# swapoff –a

關閉所有 swap partitions

# blkid
/dev/sda1: LABEL="/" UUID="dec5d8be-d75d-4440-a592-d12e837e90e6" TYPE="ext3"
/dev/sda2: LABEL="SWAP-hdc2" TYPE="swap"
/dev/sdb1: UUID="a84e9fa7-255e-435e-8d9f-e5b613895771" TYPE="xfs"

列出 UUID

# swapon –U 
# swapon –L

指定某 uuid 或某 label 開啟特定的 swap

Linux 硬碟簡單的測速 

# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   29992 MB in  1.99 seconds = 15061.91 MB/sec
 Timing buffered disk reads:  438 MB in  3.01 seconds = 145.69 MB/sec

這個是 SAS 15K 的速度

# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   20900 MB in  2.00 seconds = 10464.95 MB/sec
 Timing buffered disk reads:  896 MB in  3.00 seconds = 298.28 MB/sec

這個是 SAS 15K 兩顆做 RAID 0 的速度

# hdparm -tT /dev/md127

/dev/md127:
 Timing cached reads:   22506 MB in  2.00 seconds = 11269.49 MB/sec
 Timing buffered disk reads:  718 MB in  3.00 seconds = 239.31 MB/sec

這是 SATA 7.2K 兩顆做 RAID 0 的速度

# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   9284 MB in  2.00 seconds = 4647.05 MB/sec
 Timing buffered disk reads:  476 MB in  3.01 seconds = 158.34 MB/sec

這是 SSD 硬碟. 意外發現. 我好像沒有驅動好. T_T

#  hdparm -I /dev/sda | grep SATA
Transport: Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5
           *    SATA-I signaling speed (1.5Gb/s)
           *    SATA-II signaling speed (3.0Gb/s)

理論上 SATA II 可以達到 3.0Gb/s 也就是 384 MB/s 怪哉~

# hdparm -tT /dev/sdb

/dev/sdb:
 Timing cached reads:   11688 MB in  2.00 seconds = 5852.55 MB/sec
 Timing buffered disk reads:  1564 MB in  3.00 seconds = 521.01 MB/sec

這是磁碟陣列. XD

# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   25788 MB in  1.99 seconds = 12943.70 MB/sec
 Timing buffered disk reads:  376 MB in  3.00 seconds = 125.22 MB/sec

另外一個比較舊的磁碟陣列

查看 linux swap 使用狀況 

Mem:  16427616k total, 16374588k used,    53028k free,      872k buffers
top - 16:48:42 up 153 days,  6:12,  3 users,  load average: 1.90, 2.02, 2.04
Tasks: 1210 total,   2 running, 1208 sleeping,   0 stopped,   0 zombie
Cpu(s): 12.5%us,  1.2%sy,  0.0%ni, 85.9%id,  0.0%wa,  0.1%hi,  0.2%si,  0.0%st
Mem:  16427616k total, 16371592k used,    56024k free,      524k buffers
Swap: 16779884k total,      208k used, 16779676k free, 15398336k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
29369 root      25   0 94600 7904 2632 R 98.5  0.0 118:27.17 sshd

一般而言用 top 指令. 預設是看不到 swap. 所以要額外按一些按鈕. 進去 top 然後按 O 再按 p 最後按 enter 就可以看到 swap

top - 16:50:29 up 153 days,  6:14,  3 users,  load average: 1.80, 1.94, 2.00
Tasks: 1210 total,   3 running, 1207 sleeping,   0 stopped,   0 zombie
Cpu(s): 11.6%us,  2.1%sy,  0.0%ni, 85.8%id,  0.0%wa,  0.0%hi,  0.5%si,  0.0%st
Mem:  16427616k total, 16189080k used,   238536k free,      692k buffers
Swap: 16779884k total,      208k used, 16779676k free, 15218204k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  SWAP COMMAND
 8898 root      18   0  151m 6724  972 S  0.0  0.0   0:00.01 144m hpssd.py