I have a box running CentOS 5.3 with two Dataport removable drive bays installed on the second IDE interface (/dev/hdc and hdd). I want to configure it so I can plug in and mount various drives at different times, including different size drives. So far it will only recognize the first drive I plug in, and only if I boot the box after inserting the drive.
Is there any way to set it up so I can mount different size drives freely without having to reboot each time?
Thank you,
Bob McConnell N2SPP
At Sun, 20 Dec 2009 08:49:02 -0500 CentOS mailing list centos@centos.org wrote:
I have a box running CentOS 5.3 with two Dataport removable drive bays installed on the second IDE interface (/dev/hdc and hdd). I want to configure it so I can plug in and mount various drives at different times, including different size drives. So far it will only recognize the first drive I plug in, and only if I boot the box after inserting the drive.
Is there any way to set it up so I can mount different size drives freely without having to reboot each time?
PATA (IDE) drives are not hot-swapable -- I don't think either the kernel IDE driver or many (if any) plain IDE controllers support hot swapping (probably some IDE *hardware RAID* controllers *might* support hot swapping). Most newer SATA controllers, and *some* SCSI controllers support hot swapping. You are probably better off getting USB<=>IDE external enclosures if you want 'hot swapable' functionallity, otherwise you will need to reboot to see the change in IDE drives. USB drives are implicitly hot swappable.
Also: to get the second drive to be seen, it would have to be configured as a slave -- you'll have to set the slave jumper on the drive itself -- I think that the IDE 'removable' drive carriers don't jumper the master/slave -- actually they can't, since the IDE interface does not support drive ID. SCSI hot swap is handled by the SCA (80 pin, which include power and id) and SATA is one drive one controller port -- logically one drive one logical controller, with no drive IDs at all. (SATA is designed from the ground up to be hot swapable.)
Thank you,
Bob McConnell N2SPP _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On Sun, Dec 20, 2009 at 09:27:09AM -0500, Robert Heller wrote:
PATA (IDE) drives are not hot-swapable -- I don't think either the kernel IDE driver or many (if any) plain IDE controllers support hot
Annoyingly old kernels used to (2.2? 2.4? Can't remember). You could do "hdparm -b 0 /dev/hdg" (for example) to remove the bus from the kernel then you could swap the disk, then "hdparm -b 1 /dev/hdg" to reinsert it; this caused the kernel to rescan the bus and find the new disk and partitions. I used to do this all the time using a cheap hotswap bay. (Caveat: disk needed to be inserted at boot time to cause /dev/hd? to exist).
The PATA drivers got rewritten at some point which caused this functionality to get lost. Now I'm doing this with a USB enclosure instead, so I've not checked recently to see if it ever got re-added.