Chris's AIX Blog

Q: Does alt_disk_copy convert JFS filesystems to JFS2?
A: Yes! Starting at 6100-04, a new flag was introduced that would convert JFS filesystems to JFS2. We now have the -T which does the conversion.

http://www-01.ibm.com/support/docview.wss?uid=isg3T1011055

 

Here’s an example of converting rootvg file systems from JFS to JFS2 using alt_disk_copy.

 

My lab system was migrated from AIX 5.3 to 7.1 via nimadm. Unfortunately, nimadm does not convert JFS file systems to JFS2 during the migration. So, in this case, even though I’ve migrated to AIX 7.1 (which is a good thing) I’m still left with legacy JFS file systems in rootvg.

                                                                        

And because the AIX 5.3 version of the alt_disk_copy command does not have the –T option, I can’t convert my JFS file systems to JFS2 before I migrate to AIX 7.1. So my best option is to migrate to AIX 7.1 then convert rootvg to JFS2 file systems. A few hops in the process but it’s good enough.

 

aixlpar1 : / # lsvg -l rootvg

rootvg:

LV NAME             TYPE       LPs     PPs     PVs  LV STATE      MOUNT POINT

hd5                 boot       1       1       1    closed/syncd  N/A

hd6                 paging     32      32      1    open/syncd    N/A

hd8                 jfslog     1       1       1    open/syncd    N/A

hd4                 jfs        4       4       1    open/syncd    /

hd2                 jfs        29      29      1    open/syncd    /usr

hd9var              jfs        20      20      1    open/syncd    /var

hd3                 jfs        164     164     1    open/syncd    /tmp

hd1                 jfs        4       4       1    open/syncd    /home

hd10opt             jfs        4       4       1    open/syncd    /opt

local               jfs        4       4       1    open/syncd    /usr/local

loglv               jfs        4       4       1    open/syncd    /var/log

hd7                 sysdump    9       9       1    open/syncd    N/A

hd71                sysdump    9       9       1    open/syncd    N/A

hd11admin           jfs        2       2       1    open/syncd    /admin

 

aixlpar1 : / # oslevel -s

7100-01-01-1141

 

I clone rootvg to a spare disk using alt_disk_copy and the –T flag (which will convert the file systems to JFS2). The process converts the file systems to JFS2, as shown in the section below (highlighted in green).

 

aixlpar1 : / # alt_disk_copy -d hdisk1 -T

Source boot disk is: hdisk2

jfs2j2: Current data file /image.data moved to /image.data.acct.save.3735802.

jfs2j2: Creating new data file (/image.data).

jfs2j2: Converting filesystems in data file (/image.data) from jfs to jfs2.

jfs2j2: Converted data file (/image.data) moved to /tmp/image.data.conv.3407932.

 

jfs2j2: Cleaning up.

jfs2j2: Moving previous data file /image.data.acct.save.3735802 to IDFILE.

jfs2j2: Successfully completed converting image.data to jfs2.

Checking disk sizes.

Creating cloned rootvg volume group and associated logical volumes.

Creating logical volume alt_hd5

Creating logical volume alt_hd6

Creating logical volume alt_hd8

Creating logical volume alt_hd4

Creating logical volume alt_hd2

Creating logical volume alt_hd9var

Creating logical volume alt_hd3

Creating logical volume alt_hd1

Creating logical volume alt_hd10opt

Creating logical volume alt_local

Creating logical volume alt_loglv

Creating logical volume alt_hd7

Creating logical volume alt_hd71

Creating logical volume alt_hd11admin

Creating /alt_inst/ file system.

/alt_inst filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/admin file system.

/alt_inst/admin filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/home file system.

/alt_inst/home filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/opt file system.

/alt_inst/opt filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/tmp file system.

/alt_inst/tmp filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/usr file system.

/alt_inst/usr filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/usr/local file system.

/alt_inst/usr/local filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/var file system.

/alt_inst/var filesystem not converted.

        Small inode extents are already enabled.

Creating /alt_inst/var/log file system.

/alt_inst/var/log filesystem not converted.

        Small inode extents are already enabled.

Generating a list of files

for backup and restore into the alternate file system...

Backing-up the rootvg files and restoring them to the

alternate file system...

Running user specified customization script /tmp/cust.script.conv.3407932...

Modifying ODM on cloned disk.

Building boot image on cloned disk.

forced unmount of /alt_inst/var/log

forced unmount of /alt_inst/var

forced unmount of /alt_inst/var

forced unmount of /alt_inst/usr/local/chksys

forced unmount of /alt_inst/usr/local

forced unmount of /alt_inst/usr

forced unmount of /alt_inst/tmp

forced unmount of /alt_inst/opt

forced unmount of /alt_inst/home

forced unmount of /alt_inst/admin

forced unmount of /alt_inst

Changing logical volume names in volume group descriptor area.

Fixing LV control blocks...

Fixing file system superblocks...

Bootlist is set to the boot disk: hdisk1 blv=hd5

 

Before I reboot the system on the alternate rootvg I verify that the cloned volume group now contains JFS2 file systems only. I “wake up” the altinst_rootvg and run the lsvg command to confirm the file system is correct. I then put the altinst_rootvg to “sleep”, reboot the system and verify all rootvg file systems are mounted as jfs2.

 

aixlpar1 : / # alt_rootvg_op -W -d hdisk1

Waking up altinst_rootvg volume group ...

 

aixlpar1 : / # lsvg -l altinst_rootvg

altinst_rootvg:

LV NAME             TYPE       LPs     PPs     PVs  LV STATE      MOUNT POINT

alt_hd5             boot       1       1       1    closed/syncd  N/A

alt_hd6             paging     32      32      1    closed/syncd  N/A

alt_hd8             jfs2log    1       1       1    open/syncd    N/A

alt_hd4             jfs2       4       4       1    open/syncd    /alt_inst

alt_hd2             jfs2       29      29      1    open/syncd    /alt_inst/usr

alt_hd9var          jfs2       20      20      1    open/syncd    /alt_inst/var

alt_hd3             jfs2       164     164     1    open/syncd    /alt_inst/tmp

alt_hd1             jfs2       4       4       1    open/syncd    /alt_inst/home

alt_hd10opt         jfs2       4       4       1    open/syncd    /alt_inst/opt

alt_local           jfs2       4       4       1    open/syncd    /alt_inst/usr/local

alt_loglv           jfs2       4       4       1    open/syncd    /alt_inst/var/log

alt_hd7             sysdump    9       9       1    closed/syncd  N/A

alt_hd71            sysdump    9       9       1    closed/syncd  N/A

alt_hd11admin       jfs2       2       2       1    open/syncd    /alt_inst/admin

 

aixlpar1 : / # alt_rootvg_op -S altinst_rootvg

Putting volume group altinst_rootvg to sleep ...

forced unmount of /alt_inst/var/log

forced unmount of /alt_inst/var

forced unmount of /alt_inst/usr/local

forced unmount of /alt_inst/usr

forced unmount of /alt_inst/tmp

forced unmount of /alt_inst/opt

forced unmount of /alt_inst/home

forced unmount of /alt_inst/admin

forced unmount of /alt_inst

Fixing LV control blocks...

Fixing file system superblocks...

aixlpar1 : / #

 

; Reboot on the alternate rootvg hdisk

 

aixlpar1 : / # uptime

  10:18AM   up 1 min,  1 user,  load average: 0.32, 0.09, 0.03

 

aixlpar1 : / # lspv

hdisk1          00c342c637f21a59                    rootvg          active

hdisk2          00c342c6161c6b47                    old_rootvg

 

aixlpar1 : / # df

Filesystem    512-blocks      Free %Used    Iused %Iused Mounted on

/dev/hd4          524288    411568   22%     3040     7% /

/dev/hd2         3801088    537176   86%    34089    35% /usr

/dev/hd9var      2621440   2413520    8%     3554     2% /var

/dev/hd3        21495808  21476312    1%      110     1% /tmp

/dev/hd1          524288    522456    1%       90     1% /home

/proc                  -         -    -         -     -  /proc

/dev/hd10opt      524288    266560   50%     5133    15% /opt

/dev/local        524288    495320    6%      249     1% /usr/local

/dev/loglv        524288    522040    1%       49     1% /var/log

/dev/hd11admin     262144    261384    1%        7     1% /admin

 

aixlpar1 : / # lsvg -l rootvg

rootvg:

LV NAME             TYPE       LPs     PPs     PVs  LV STATE      MOUNT POINT

hd5                 boot       1       1       1    closed/syncd  N/A

hd6                 paging     32      32      1    open/syncd    N/A

hd8                 jfs2log    1       1       1    open/syncd    N/A

hd4                 jfs2       4       4       1    open/syncd    /

hd2                 jfs2       29      29      1    open/syncd    /usr

hd9var              jfs2       20      20      1    open/syncd    /var

hd3                 jfs2       164     164     1    open/syncd    /tmp

hd1                 jfs2       4       4       1    open/syncd    /home

hd10opt             jfs2       4       4       1    open/syncd    /opt

local               jfs2       4       4       1    open/syncd    /usr/local

loglv               jfs2       4       4       1    open/syncd    /var/log

hd7                 sysdump    9       9       1    open/syncd    N/A

hd71                sysdump    9       9       1    open/syncd    N/A

hd11admin           jfs2       2       2       1    open/syncd    /admin

 

===

The message “filesystem not converted” (below) is not related to the JFS to JFS2 conversion. This messge refers to whether or not the file system needs to be changed to use Variable Inode Extents (VIX). This is the default setting for JFS2 file systems.

 

Creating /alt_inst/ file system.

/alt_inst filesystem not converted.

        Small inode extents are already enabled.

 

aixlpar1 : / # lsfs -q /

Name            Nodename   Mount Pt               VFS   Size    Options    Auto Accounting

/dev/hd4        --         /                      jfs2  524288  --         yes  no

  (lv size: 524288, fs size: 524288, block size: 4096, sparse files: yes, inline log: no, inline log size: 0, EAformat: v1, Quota: no, DMAPI: no, VIX: yes, EFS: no, ISNAPSHOT: no, MAXEXT: 0, MountGuard: no)

aixlpar1 : / #

 

Please refer to the following link for more information on VIX in AIX.

 

Use of Variable Inode Extents (VIX) in AIX

http://www-01.ibm.com/support/docview.wss?uid=isg3T1010368

===

 

Why would I want to convert rootvg to JFS2 anyway? Well for starters, it’s generally considered best practice to use JFS2 as it offers several performance & scalability enhancements over JFS. For example, you cannot create files greater than 2GB on JFS, unless the file system was created as “large (big) file” enabled; jfs file systems in rootvg were never created as large file enabled.

 

Another reason…..eventually JFS will be retired.

 

Here’s an example of a potential problem with JFS in rootvg. You try to create a file of a size greater than 2GB in /tmp (type jfs). Even though the ulimit settings are not restricting the creation of a file of this size, the JFS file system will not allow it. The file creation process fails. The bf attribute for the /tmp file system is set to false. This indicates the file system is not “large file” enabled.

 

aixlpar1 : /tmp # df -g .

Filesystem    GB blocks      Free %Used    Iused %Iused Mounted on

/dev/hd3          10.25      6.94   33%      117     1% /tmp

 

aixlpar1 : /tmp # cat 1gbfile 1gbfile 1gbfile > 3gbfile

cat: 0652-054 Cannot write to output.

Error 0

 

aixlpar1 : /tmp # ulimit -a

time(seconds)        unlimited

file(blocks)         unlimited

data(kbytes)         unlimited

stack(kbytes)        unlimited

memory(kbytes)       unlimited

coredump(blocks)     2097151

nofiles(descriptors) unlimited

threads(per process) unlimited

processes(per user)  unlimited

 

aixlpar1 : /tmp # lsfs -q /tmp

Name            Nodename   Mount Pt               VFS   Size    Options    Auto Accounting

/dev/hd3        --         /tmp                   jfs   21495808 --         yes  no

  (lv size: 21495808, fs size: 21495808, frag size: 4096, nbpi: 4096, compress: no, bf: false, ag: 8)

 

OK, so creating files greater than 2GB in rootvg is probably not a big problem for most AIX shops. But why risk it! My advice is to always use JFS2 (even in rootvg).

 

Keep this in mind when migrating from AIX 5.3 to 6.1 or 7.1 via nimadm.

 

The following link provides an overview and comparison of both JFS and JFS2 file systems.

 

http://pic.dhe.ibm.com/infocenter/aix/v7r1/topic/com.ibm.aix.baseadmn/doc/baseadmndita/fs_jfs_jfs2.htm