How to reread disk size?

Hi all,
I have a system with hot swappable bays but one of the involved controllers apparently does not support hot swap:
(I have unfortunately an old kernel: 2.6.24)

00:1f.2 IDE interface: Intel Corporation 631xESB/632xESB/3100 Chipset SATA IDE Controller (rev 09) (prog-if 8f [Master SecP SecO PriP PriO])
Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 19 I/O ports at 18c8 [size=8]
I/O ports at 18ac [size=4]
I/O ports at 18c0 [size=8]
I/O ports at 18a8 [size=4]
I/O ports at 18b0 [size=16]
Memory at da804400 (32-bit, non-prefetchable) [size=1K]
Capabilities: [70] Power Management version 2

I have swapped the disk with a larger one (750GB -> 1TB) but it blockdev --getsize64 still sees the old size. It has not realized I have swapped disk.

In the past I was doing:

blockdev --rereadpt /dev/sdX

and it usually worked on other controllers to reread the size visible from "blockdev --getsize" or "blockdev --getsize64". One time I think it even worked on exactly *that* controller... but it's not working now, it's strange.

Is there a technique, or I am out of luck?
The machine should not be rebooted
I would even enter the size manually if possible: I know how many LBA blocks are in that disk.

Quoted 10 lines

[CUT]
In the past I was doing:

blockdev --rereadpt /dev/sdX

and it usually worked on other controllers to reread the size visible from "blockdev --getsize" or "blockdev --getsize64". One time I think it even worked on exactly *that* controller... but it's not working now, it's strange.

Quoted 4 lines

Is there a technique, or I am out of luck?
The machine should not be rebooted
I would even enter the size manually if possible: I know how many LBA blocks are in that disk.

What dmesg output do you get when you do this?

[...]
It rereads the wrong size, i.e. the one of the old disk :-(
I am sure sdr is the correct disk, I even identified it by doing dd if=/dev/sdr of=/dev/null and then looking at the activity led to confirm it's the right drive. It should have read a size of 1TB.

Quoted 10 lines · Robert Hancock

Quoted 10 lines

[CUT]
In the past I was doing:

blockdev --rereadpt /dev/sdX

and it usually worked on other controllers to reread the size visible from "blockdev --getsize" or "blockdev --getsize64". One time I think it even worked on exactly *that* controller... but it's not working now, it's strange.

Quoted 6 lines

Quoted 4 lines

Is there a technique, or I am out of luck?
The machine should not be rebooted
I would even enter the size manually if possible: I know how many LBA blocks are in that disk.

What dmesg output do you get when you do this?

with "this" I suppose you mean the blockdev --rereadpt?

This is the dmesg I get upon blockdev --rereadpt:

[508100.472337] sd 3:0:1:0: [sdr] 1465149168 512-byte hardware sectors 
(750156 MB)
[508100.472376] sd 3:0:1:0: [sdr] Write Protect is off
[508100.472381] sd 3:0:1:0: [sdr] Mode Sense: 00 3a 00 00
[508100.472412] sd 3:0:1:0: [sdr] Write cache: enabled, read cache: 
enabled, doesn't support DPO or FUA
[508100.472418]  sdr: unknown partition table

It rereads the wrong size, i.e. the one of the old disk :-( I am sure sdr is the correct disk, I even identified it by doing dd if=/dev/sdr of=/dev/null and then looking at the activity led to confirm it's the right drive. It should have read a size of 1TB.

ata_piix doesn't have a way to get automatically notified that the disk has been hotplugged since the chipset doesn't support it in this mode. (The ideal solution would be to switch the controller into AHCI mode, but I don't know if that's possible on that chipset and BIOS.)

I think there are some ways to get the code to recheck the disk however.. you can try echoing something into the "rescan" sysfs file under /sys that matches your device (do a "find /sys/ -name scsi_level" to see what directories they're in, the rescan file is in the same directory).

Quoted 11 lines · Robert Hancock

ata_piix doesn't have a way to get automatically notified that the disk has been hotplugged since the chipset doesn't support it in this mode. (The ideal solution would be to switch the controller into AHCI mode, but I don't know if that's possible on that chipset and BIOS.)

I think there are some ways to get the code to recheck the disk however.. you can try echoing something into the "rescan" sysfs file under /sys that matches your device (do a "find /sys/ -name scsi_level" to see what directories they're in, the rescan file is in the same directory).

Thanks for the hint
It doesn't work unfortunately.
Echoing something into rescan makes it output (in dmesg) basically the same message that comes out with blockdev --rereadpt /dev/sdr. The size is still detected wrong. Catting "model" also turns out that the old brand of disk still being detected. smartctl -a does show the new disk :-) I tried to write "1" in evt_media_change but it's permission denied :-)

Quoted 14 lines · Asdo

Quoted 5 lines · Robert Hancock

ata_piix doesn't have a way to get automatically notified that the disk has been hotplugged since the chipset doesn't support it in this mode. (The ideal solution would be to switch the controller into AHCI mode, but I don't know if that's possible on that chipset and BIOS.)

Quoted 7 lines

I think there are some ways to get the code to recheck the disk however.. you can try echoing something into the "rescan" sysfs file under /sys that matches your device (do a "find /sys/ -name scsi_level" to see what directories they're in, the rescan file is in the same directory).

Quoted 5 lines

Thanks for the hint
It doesn't work unfortunately.
Echoing something into rescan makes it output (in dmesg) basically the same message that comes out with blockdev --rereadpt /dev/sdr. The size is still detected wrong. Catting "model" also turns out that the old brand of disk still being detected. smartctl -a does show the new disk :-) I tried to write "1" in evt_media_change but it's permission denied :-)

Right. libata caches the value from the moment it scans the device. You might be able to alter it by having the device destroyed and recreated ... that would be echoing 1 to the delete under the scsi device sysfs node and then echoing '- - -' to the host rescan parameter. If that doesn't work, libata will need to be fixed somehow because that would mean it isn't slaving it's device lifetimes to the SCSI model.