원문 : http://www.ischo.net -- 조인상 // 시스템 엔지니어

Writer : http://www.ischo.net -- ischo // System Engineer in Replubic Of Korea

+++++++++++++++++++++++++++++++++++++++++++++++++++++++

 

원문 : http://www.ischo.net -- 조인상 //시스템 엔지니어

 

출처 : IBM

           http://www-01.ibm.com/support/docview.wss?uid=isg3T1000459

+++++++++++++++++++++++++++++++++++++++++++++++++++++++

 

32KB 이상 파일 복사시 out of memory 에러 발생에 대한 복구(indirect segment 문제)

 

Recovery From ENOMEM Error When Copying Files Larger Than 32K (.indirect segment pblm)

 Technote (FAQ)
 
Question
Recovery From ENOMEM Error When Copying Files Larger Than 32K (.indirect segment pblm)
 
Answer
  • Environment
  • Background
  • The problem and the solution
  • Recommended fixes

  • Environment

    APAR IY13763 was created to correct the error and is intended for JFS only and no other filesystem types (JFS2, AFS, GPFS, etc). This fix applies to Standard/Large/Compressed JFS types on systems running AIX 4.3.3. At AIX 5.1 JFS and JFS2 filesystems by default are not affected by this problem.

    Background

    Here is a brief overview of the journaled file system geometry:
    • JFS uses direct, single indirect, and double indirect disk addressing. The disk inode contains 9 slots for disk addresses. The first 8 are used for the direct addressing, while the ninth is used for indirect addressing.

    • Direct addressing

      If the file is les than or equal to 32K, then the file will use direct addressing, which means the inode will point directly to the data blocks.

    • Single Indirect addressing

      If the file is too larger for direct addressing, it will use a form of indirect addressing. Single indirect addressing is called when the file's data blocks can be addressed by a single indirect block. In this case, the direct block addresses are unused and the indirect block address contains the disk address of the one and only indirect block. Each 4 byte entry in the indrect block refers to a data block; therefore, single indirect addressing is used for files greater than 32K yet less than 4MB.

    • Double Indirect addressing

      If the file is larger than 4 MB, double indirect addressing is used. In this case, the indirect field contains the block number of the double indirect block for the file. The double indirect block contains 512 pointers to the indirect blocks. As stated before, each indirect block contains 1024 block addresses for the data for the file.

      For more in-depth coverage of this subject, the following IBM publications are recommended:

      • AIX Logical Volume Manager, from A to Z: Introduction and Concepts
      • AIX V4 documentation library

      The problem and the solution

      The problem with the ENOMEM error occurs when the system has reached an architectural limit in AIX. The data read from the indirect blocks of the filesystem are cached in an indirect segment of virtual memory. Once the indirect data has been cached, it remains in virtual memory until the filesystem is unmounted. Once this segment is full, there is no more room to cache data and the result is the 'out of memory' error message.

      Note that the problem is with the indirect data and since a file that is less than 32K does not use indirect blocks, these smaller files are not affected by the problem.

      A temporary work-around for this problem is unmounting and remounting the filesystem, which clears out the .indirect cache. Here are the procedures for correcting the problem: APAR IY13763 (orginally IY11431) increases the number of 256MB indirect segments from one to eight. If this is not already applied to the system, it can either be downloaded from "Quick links to AIX fixes" website or ordered.

      First check to see if you may already have this APAR installed.

      # instfix -ik IY13763 
      
      If it is there you will receive the informational message:
      All filesets for IY13763 were found 
      
      If you do receive this message, proceed with the procedures provided below. If you do not receive this message, first apply the fix and then complete the following steps for the filesystem(s) affected:

      1. # umount /fsname 
        

      2. # chfs -a options=rw,mind /fsname 
        
        This step will not only update /etc/filesystems, but will place the information in the LVCB (logical volume control block). The "mind" (Multi INDirect) option, will allow that filesystem to use the eight .indirect segments instead of one.

      3. # mount /fsname 
        
      4. Verify the filesystem is mounted with the correct options:
        # mount 
        
        You should see something similar to the following:
         
        /dev/lvname      /fsname               jfs    Jun 27 14:40 
        rw,mind,log=/dev/loglv05 
        
         
      5. Other than implementing these procedures, updating the operating system to 5.1 is the only other option.

        Recommended fixes

        APAR             DESCRIPTION                            AIX LEVEL 
        IY13763          MULTI-SEGMENT .INDIRECT FOR JFS        4.3.3. 
        
 
 
Historical Number
isg1pTechnote0777

번호 제목 글쓴이 날짜 조회 수
공지 [공지] 게시자료 열람자유. 불펌금지입니다. 조인상 2010.12.07 109880
151 AIX 6 VM관련 OS parameter secret 조인상 2010.08.26 1
150 AIX 6.1 aio 설정법 조인상 2010.07.06 24228
149 IBM x시리즈 드라이버 업데이트 팩 file 조인상 2010.07.01 15776
148 IBM p시리즈 ASM/시리얼접속방법 조인상 2010.07.01 30995
147 IBM xSeries 펌웨어 업데이트를 위한 BoMC(Bootable Media Center) 사용법 file 조인상 2010.06.29 31504
146 Optimizing AIX 5L performance - AIX 5L시리즈 메모리 튜닝 조인상 2010.06.22 29366
145 ODM에 남아있는 Default Gateway 정보 삭제하기 조인상 2010.06.21 21160
144 Command is Respawning Too Rapidly. 3A30359F 조인상 2010.06.17 18774
143 pSeriese 온도 확인 방법 조인상 2010.06.17 21006
142 LPAR의 Memory Overhead (Hypervisor Memory) 사용량에 대하여 secret 조인상 2010.06.11 0
» 32KB 이상 파일 복사시 out of memory 에러 발생에 대한 복구(indirect segment 문제) 조인상 2010.06.10 19646
140 AIX에서 dump 강제로 받는 방법 file 조인상 2010.06.09 19414
139 AIX 환경에서 NFS port번호 range 지정방법 조인상 2010.06.04 37868
138 IBM 문서용 폰트 file 조인상 2010.06.04 16773
137 000-104 information secret 조인상 2010.06.02 1
136 신규시험 정보 Test 000-104: AIX 6.1 Administration 조인상 2010.06.02 24823
135 서버측HMC port ip확인하기 [3] 조인상 2010.05.14 27726
134 [매뉴얼] IBM p시리즈 머신에 레드햇리눅스 설치하기 file 조인상 2010.05.12 18300
133 BC & x시리즈 전력량 계산기 file 조인상 2010.05.11 17899
132 c 컴파일러 설치하기 조인상 2010.05.11 23265
서버에 요청 중입니다. 잠시만 기다려 주십시오...