一台文件存储服务器单目录下子目录已经突破31998数限制，造成无法继续创建子目录，服务器系统环境为CentOS5.4 内核版本为2.6.18。解决方案只能是升级到ext4文件系统，首先到https://ext4.wiki.kernel.org/index.php/Ext4_Howto查了一下资料，文中的第一句便是“Ext4 was released as a functionally complete and stable filesystem in Linux 2.6.28”。难道只能升级内核一条路了吗？当然不是：）呵呵，下面总结本人实施/www分区从ext3升级至ext4步骤供大家参考。
一、升级前状态
[root@USER-SERVER ~]# dfFilesystem 1K-blocks Used Available Use% Mounted on/dev/sda2 20315844 2342008 16925196 13% //dev/sda5 129863460 192192 122968152 1% /www/dev/sda1 194442 17798 166605 10% /boottmpfs 1029680 0 1029680 0% /dev/shm
无任何信息返回，说明/dev/sda5的ext4特征没有激活
[root@USER-SERVER ~]# tune2fs -l /dev/sda5 | grep extent[root@USER-SERVER ~]#
安装所需包源码安装：
wget http://ftp.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/e2fsprogs-1.41.14.tar.gztar zxvf e2fsprogs-1.41.14.tar.gz; cd e2fsprogs-1.41.14./configuremake;make install
二、制作引导镜像查找并加载相应的模块，如只需ext4支持，可将--with=ext3去掉
[root@USER-SERVER boot]# mv /boot/initrd-`uname -r`.img /boot/initrd-`uname -r`.img.old[root@USER-SERVER boot]# mkinitrd -v --with=ext4 --with=ext3 /boot/initrd-`uname -r`.img `uname -r`Creating initramfsLooking for deps of module ehci-hcdLooking for deps of module ohci-hcdLooking for deps of module uhci-hcdLooking for deps of module ext3: jbd Looking for deps of module jbdFound root device sda2 for LABEL=/Looking for driver for device sda2Looking for deps of module pci:v00008086d00002680sv000017AAsd00006B7Cbc01sc01i8f: scsi_mod libata ata_piix Looking for deps of module scsi_modLooking for deps of module sd_mod: scsi_mod Looking for deps of module libata: scsi_mod Looking for deps of module ata_piix: scsi_mod libata Looking for driver for device sda3Looking for deps of module pci:v00008086d00002680sv000017AAsd00006B7Cbc01sc01i8f: scsi_mod libata ata_piix Looking for deps of module usb-storage: scsi_mod Looking for deps of module ide-diskLooking for deps of module dm-mem-cacheLooking for deps of module dm-region_hash: dm-mod dm-log Looking for deps of module dm-modLooking for deps of module dm-log: dm-mod Looking for deps of module dm-messageLooking for deps of module dm-raid45: dm-message dm-mod dm-mem-cache dm-log dm-region_hash Looking for deps of module ext4: crc16 jbd2 Looking for deps of module crc16Looking for deps of module jbd2Using modules: /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/ehci-hcd.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/ohci-hcd.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/uhci-hcd.ko /lib/modules/2.6.18-164.15.1.el5/kernel/fs/jbd/jbd.ko /lib/modules/2.6.18-164.15.1.el5/kernel/fs/ext3/ext3.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/scsi/scsi_mod.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/scsi/sd_mod.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/ata/libata.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/ata/ata_piix.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/storage/usb-storage.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-mem-cache.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-mod.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-log.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-region_hash.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-message.ko /lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-raid45.ko /lib/modules/2.6.18-164.15.1.el5/kernel/lib/crc16.ko /lib/modules/2.6.18-164.15.1.el5/kernel/fs/jbd2/jbd2.ko /lib/modules/2.6.18-164.15.1.el5/kernel/fs/ext4/ext4.ko/sbin/nash -> /tmp/initrd.qO3680/bin/nash/sbin/insmod.static -> /tmp/initrd.qO3680/bin/insmodcopy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/ehci-hcd.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/ehci-hcd.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/ohci-hcd.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/ohci-hcd.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/host/uhci-hcd.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/uhci-hcd.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/fs/jbd/jbd.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/jbd.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/fs/ext3/ext3.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/ext3.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/scsi/scsi_mod.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/scsi_mod.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/scsi/sd_mod.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/sd_mod.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/ata/libata.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/libata.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/ata/ata_piix.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/ata_piix.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/usb/storage/usb-storage.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/usb-storage.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-mem-cache.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-mem-cache.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-mod.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-mod.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-log.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-log.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-region_hash.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-region_hash.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-message.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-message.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/drivers/md/dm-raid45.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/dm-raid45.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/lib/crc16.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/crc16.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/fs/jbd2/jbd2.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/jbd2.ko' [elf64-x86-64]copy from `/lib/modules/2.6.18-164.15.1.el5/kernel/fs/ext4/ext4.ko' [elf64-x86-64] to `/tmp/initrd.qO3680/lib/ext4.ko' [elf64-x86-64]/sbin/dmraid.static -> /tmp/initrd.qO3680/bin/dmraid/sbin/kpartx.static -> /tmp/initrd.qO3680/bin/kpartxAdding module ehci-hcdAdding module ohci-hcdAdding module uhci-hcdAdding module jbdAdding module ext3Adding module scsi_modAdding module sd_modAdding module libataAdding module ata_piixAdding module usb-storageAdding module dm-mem-cacheAdding module dm-modAdding module dm-logAdding module dm-region_hashAdding module dm-messageAdding module dm-raid45Adding module crc16Adding module jbd2Adding module ext4
重启[root@USER-SERVER ~]# reboot三、格式转换[root@USER-SERVER ~]# umount /dev/sda5[root@USER-SERVER ~]# tune2fs -O has_journal,extents,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize /dev/sda5
tune2fs 1.41.12 (17-May-2010)Please run e2fsck on the filesystem.
四、修改转换文件系统错误并挂载[root@USER-SERVER ~]# e2fsck -fDC0 /dev/sda5 -y[root@USER-SERVER ~]# mount -t ext4 /dev/sda5 /www五、修改文件系统信息(重要！否则重启后会还原为ext3)将LABEL=/www /www ext3 defaults 1 2修改为LABEL=/www /www ext4 defaults 1 2[root@USER-SERVER ~]# vi /etc/fstab
root@USER-SERVER ~]# vi /etc/fstabLABEL=/ / ext3 defaults 1 1LABEL=/www /www ext4 defaults 1 2LABEL=/boot /boot ext3 defaults 1 2tmpfs /dev/shm tmpfs defaults 0 0devpts /dev/pts devpts gid=5,mode=620 0 0sysfs /sys sysfs defaults 0 0proc /proc proc defaults 0 0LABEL=SWAP-sda3 swap swap defaults 0 0
六、升级后状态ext4的特征全激活了：）#[root@USER-SERVER ~]# tune2fs -l /dev/sda5 | grep extent
Filesystem features: has_journal resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
[root@USER-SERVER ~]# df -T
Filesystem Type 1K-blocks Used Available Use% Mounted on/dev/sda2 ext3 20315844 2310764 16956440 12% //dev/sda1 ext3 194442 20563 163840 12% /boottmpfs tmpfs 1029672 0 1029672 0% /dev/shm/dev/sda5 ext4 129863460 192192 122968152 1% /www
参考文献http://fedorasolved.org/Members/rasker/converting-an-ext3-root-partition-to-ext4-in-fedora-10http://kernelnewbies.org/Ext4#head-3891522e0601162aab24c73c1f148a1e28c6a9d4
转载:http://blog.liuts.com/post/211/
