Hi guys!
I have a server whith CentOS 5.2,it's filesystem become read-only yesterday.

in single mode,enter:
#mount -o rw,remount /dev/sda3 /
#reboot

after all , everything ok.
but It becomes read-only again in this morning!

enter single mode, then:
#mount -o rw,remount /dev/sda3 /
#reboot

It becomes ok. - -||


info:
[root@rednet ~]# fdisk -l
Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 60801 488279610 8e Linux LVM

[root@rednet ~]# df -lh
/dev/mapper/VolGroup00-LogVol00
450G 134G 293G 32% /
/dev/sda1 99M 12M 83M 13% /boot
tmpfs 2.0G 0 2.0G 0% /dev/shm

[root@rednet ~]# cat /etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0

[root@rednet ~]# cat /var/log/messages
........
........
Mar 10 12:43:40 rednet kernel: Descriptor sense data with sense descriptors (in hex):
Mar 10 12:43:40 rednet kernel: 72 0b 14 00 00 00 00 0c 00 0a 80 00 00 00 00 00
Mar 10 12:43:40 rednet kernel: 27 06 e0 e5
Mar 10 12:43:40 rednet kernel: end_request: I/O error, dev sda, sector 654762213
Mar 10 12:43:40 rednet kernel: printk: 118 messages suppressed.
Mar 10 12:43:40 rednet kernel: Buffer I/O error on device dm-0, logical block 81819123
Mar 10 12:43:40 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:40 rednet kernel: ata2: EH complete
Mar 10 12:43:40 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:40 rednet kernel: sda: Write Protect is off
Mar 10 12:43:40 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:42 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:42 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:42 rednet kernel: ata2.00: cmd 25/00:00:cd:5b:19/00:02:25:00:00/e0 tag 0 dma 262144 in
Mar 10 12:43:42 rednet kernel: res 51/40:00:cd:5b:19/40:02:25:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:42 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:42 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:42 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:42 rednet kernel: ata2: EH complete
Mar 10 12:43:42 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:42 rednet kernel: sda: Write Protect is off
Mar 10 12:43:42 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:42 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:42 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:42 rednet kernel: ata2.00: cmd 25/00:08:05:78:d6/00:00:25:00:00/e0 tag 0 dma 4096 in
Mar 10 12:43:42 rednet kernel: res 51/40:08:05:78:d6/40:00:25:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:42 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:42 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:42 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:42 rednet kernel: ata2: EH complete
Mar 10 12:43:42 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:42 rednet kernel: sda: Write Protect is off
Mar 10 12:43:42 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:42 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:42 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:42 rednet kernel: ata2.00: cmd 35/00:00:65:a5:02/00:04:27:00:00/e0 tag 0 dma 524288 out
Mar 10 12:43:42 rednet kernel: res 51/10:00:65:a5:02/10:04:27:00:00/e0 Emask 0x81 (invalid argument)
Mar 10 12:43:42 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:42 rednet kernel: ata2.00: error: { IDNF }
Mar 10 12:43:42 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:42 rednet kernel: sd 1:0:0:0: SCSI error: return code = 0x08000002
Mar 10 12:43:42 rednet kernel: sda: Current [descriptor]: sense key: Aborted Command
Mar 10 12:43:42 rednet kernel: Add. Sense: Recorded entity not found
Mar 10 12:43:42 rednet kernel:
Mar 10 12:43:42 rednet kernel: Descriptor sense data with sense descriptors (in hex):
Mar 10 12:43:42 rednet kernel: 72 0b 14 00 00 00 00 0c 00 0a 80 00 00 00 00 00
Mar 10 12:43:42 rednet kernel: 27 02 a5 65
Mar 10 12:43:42 rednet kernel: end_request: I/O error, dev sda, sector 654484837
Mar 10 12:43:42 rednet kernel: printk: 127 messages suppressed.
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784451
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784452
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784453
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784454
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784455
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784456
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784457
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784458
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784459
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81784460
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: ata2: EH complete
Mar 10 12:43:42 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:42 rednet kernel: sda: Write Protect is off
Mar 10 12:43:42 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:42 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:42 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:42 rednet kernel: ata2.00: cmd 25/00:08:4d:31:1f/00:00:27:00:00/e0 tag 0 dma 4096 in
Mar 10 12:43:42 rednet kernel: res 51/40:08:4d:31:1f/40:00:27:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:42 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:42 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:42 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:42 rednet kernel: ata2: EH complete
Mar 10 12:43:42 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:42 rednet kernel: sda: Write Protect is off
Mar 10 12:43:42 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:42 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:42 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:42 rednet kernel: ata2.00: cmd 35/00:00:ad:bc:03/00:04:27:00:00/e0 tag 0 dma 524288 out
Mar 10 12:43:42 rednet kernel: res 51/10:00:ad:bc:03/10:04:27:00:00/e0 Emask 0x81 (invalid argument)
Mar 10 12:43:42 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:42 rednet kernel: ata2.00: error: { IDNF }
Mar 10 12:43:42 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:42 rednet kernel: sd 1:0:0:0: SCSI error: return code = 0x08000002
Mar 10 12:43:42 rednet kernel: sda: Current [descriptor]: sense key: Aborted Command
Mar 10 12:43:42 rednet kernel: Add. Sense: Recorded entity not found
Mar 10 12:43:42 rednet kernel:
Mar 10 12:43:42 rednet kernel: Descriptor sense data with sense descriptors (in hex):
Mar 10 12:43:42 rednet kernel: 72 0b 14 00 00 00 00 0c 00 0a 80 00 00 00 00 00
Mar 10 12:43:42 rednet kernel: 27 03 bc ad
Mar 10 12:43:42 rednet kernel: end_request: I/O error, dev sda, sector 654556333
Mar 10 12:43:42 rednet kernel: printk: 118 messages suppressed.
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793388
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793389
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793390
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793391
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793392
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793393
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:42 rednet kernel: Buffer I/O error on device dm-0, logical block 81793394
Mar 10 12:43:42 rednet kernel: lost page write due to I/O error on dm-0
Mar 10 12:43:43 rednet kernel: ata2: EH complete
Mar 10 12:43:43 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:43 rednet kernel: sda: Write Protect is off
Mar 10 12:43:43 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:45 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:45 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:45 rednet kernel: ata2.00: cmd 25/00:00:35:3f:b1/00:02:31:00:00/e0 tag 0 dma 262144 in
Mar 10 12:43:45 rednet kernel: res 51/40:00:35:3f:b1/40:02:31:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:45 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:45 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:45 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:45 rednet kernel: ata2: EH complete
Mar 10 12:43:45 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:45 rednet kernel: sda: Write Protect is off
Mar 10 12:43:45 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:45 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:45 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:45 rednet kernel: ata2.00: cmd 25/00:48:05:89:b0/00:00:27:00:00/e0 tag 0 dma 36864 in
Mar 10 12:43:45 rednet kernel: res 51/40:48:05:89:b0/40:00:27:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:45 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:45 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:45 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:45 rednet kernel: ata2: EH complete
Mar 10 12:43:45 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:45 rednet kernel: sda: Write Protect is off
Mar 10 12:43:45 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:45 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:45 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:45 rednet kernel: ata2.00: cmd 25/00:00:1d:98:d6/00:02:25:00:00/e0 tag 0 dma 262144 in
Mar 10 12:43:45 rednet kernel: res 51/40:00:1d:98:d6/40:02:25:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:45 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:45 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:45 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:45 rednet kernel: ata2: EH complete
Mar 10 12:43:45 rednet kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Mar 10 12:43:45 rednet kernel: sda: Write Protect is off
Mar 10 12:43:45 rednet kernel: SCSI device sda: drive cache: write back
Mar 10 12:43:45 rednet kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 10 12:43:45 rednet kernel: ata2.00: BMDMA stat 0x25
Mar 10 12:43:45 rednet kernel: ata2.00: cmd 25/00:00:45:8d:b1/00:02:31:00:00/e0 tag 0 dma 262144 in
Mar 10 12:43:45 rednet kernel: res 51/40:00:45:8d:b1/40:02:31:00:00/e0 Emask 0x9 (media error)
Mar 10 12:43:45 rednet kernel: ata2.00: status: { DRDY ERR }
Mar 10 12:43:45 rednet kernel: ata2.00: error: { UNC }
Mar 10 12:43:45 rednet kernel: ata2.00: configured for UDMA/133
Mar 10 12:43:45 rednet kernel: ata2: EH complete

...............
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PS:I am very sorry that my English is so bad!

Off hand, I would guess that the disk is going. If you don't have a back up of the data on it, I'd suggest taking one now. With a back-up in place, you might want to run the SMART drive selftests (assuming the drive has SMART capabilities). The commands are "smartctl -t short /dev/sda" and "smartctl -t long /dev/sda" -- see the results with "smartctl -l selftest /dev/sda". You might want to see what other disk info you can dump through smartctl ("smartctl -l error /dev/sda" might be particularly helpful. I suggest reading the smartctl man page for more detail. Running badblocks on the disk (when it's unmounted would also be a good idea -- you can run the smartctl commands while it's mounted). If there are lots of bad blocks and the disk is making funny noises, it's probably time for a replacement.

Thinks very much!