磁带机压缩工作不正常

适用机型:
所有xSeries 225; 所有xSeries 226; 所有xSeries 235; 所有xSeries 236; 所有xSeries 345; 所有xSeries 346

文档内容：
故障现象：
当用x系列磁带机备份的时候，文件备份可能要花很长时间备份，磁带压缩工作不正常

受影响的系统：
an xSeries 346, Type 8840, any Model.
an xSeries 345, Type 8670, any Model.
an xSeries 236, Type 8841, any Model.
an xSeries 235, Type 8671, any Model.
an xSeries 226, Type 8648, any Model.
an xSeries 225, Type 8649, any Model.
an xSeries 225, Type 8647, any Model.
a ServeRAID-5i Controller,
Option p/n25P3492, FRU p/n32P0016.
a ServeRAID-6i Controller,
Option p/n71P8595, FRU p/n71P862

Adaptec AIC-7899 Wide Ultra160 SCSI controller
Adaptec AIC-7902 Ultra320 SCSI controller
LSI Logic 53C1020 Ultra320 SCSI controller
LSI Logic 53C1030 Ultra320 SCSI controller
SATA 150 SCSI controller

BM 20/40GB DDS/4 4-mm Internal SCSI Tape Drive,
Option p/n09N0730, FRU p/n48P7038
a IBM 20/40GB DDS/4 4-mm Internal SCSI Tape Drive,
Option p/n00N7991, FRU p/n48P7040
a IBM 40/80GB DLTVS Internal SCSI Tape Drive
Option p/n24P2398, FRU p/n24P2424
a IBM 40/80GB DLTVS Internal SCSI Tape Drive
Option p/n59P6719, FRU p/n24P2424
a IBM VXA-2 Tape Drive,
Option p/n59P6746, FRU p/n19P4898
a IBM 80/160GB DLTVS Internal SCSI Tape Drive,
Option p/n59P6745, FRU p/n71P9180
a IBM 100/200GB LTO Tape Drive,
Option p/n00N8016, FRU p/n37L5799
a IBM 100/200GB LTO Half-High Tape Drive,
Option p/n24P2396, FRU p/n24P2400
a IBM 100/200GB LTO Half-High Tape Drive,
Option p/n59P6717, FRU p/n24P2400
a IBM 110/220GB SDLT Internal SCSI Tape Drive,
a IBM 120/240GB DDS/4 Tape Autoloader,
Option p/n00N7992, FRU p/n24P2413
Option p/n00N8015, FRU p/n24P2418
a IBM 160/320GB SDLT Tape Drive,
Option p/n59P6736, FRU p/n59P6737
a IBM 200/400GB LTO (FH) Tape Drive,
Option p/n59P6744, FRU p/n71P9141
a 2U SDLT Tape Autoloader, Type 3607, Model 16X
a 2U LTO GEN1 Tape Autoloader, Type 3607, Model 26X
a 2U SDLT Tape Autoloader, Type 3623, Model 2SX
a 2U LTO GEN2 Tape Autoloader, Type 3623, Model 2LX
a SDLT/LTO Modular Tape Library, Type 4560, Model SLX

Windows 2000 Server, with Service Pack 4 applied.

Windows 2000 Advanced Server, with Service Pack 4 applied.

Windows Server 2003, Standard Edition, with Service Pack 1
applied.

Windows Server 2003, Enterprise Edition, with Service Pack
1 applied.
解决办法：
1.把备份软件的压缩功能禁用
2.用磁带诊断工具作压缩测试，如果可以测试通过，说明压缩工作正常，排除磁带机问题，多数跟软件有关
为了达到最好的备份效果最好禁用软件压缩
背景：
所有的xserver的磁带压缩功能是由磁带机的微码来控制的，而且默认是启用的
改变磁带机的跳线开关设置或者改变备份软件的压缩设置或者scsi控制器设置都
对硬件微码设置没有影响
对于大多数磁带诊断程序，压缩测试是由磁带机决定是否压缩可以正常工作
如果测试通过，说明磁带机问题不大，而多数是软件问题

大多数情况下，当硬件已经进行了压缩的时候，客户软件又进行压缩必然会导致压缩的速度的减慢