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Swapping IDE Drives in Linux without Rebooting?
Hasufin writes "I've got quite a few of those removable IDE drive bays in my computers. I'd like to be able to swap these drives without the need of rebooting linux. I've searched quite a bit via google and other resources but haven't found a good how-to. Any pointers? I've seen few mentions to hdparm -U & -R and a script or two, but haven't had any luck using it w/ my promise udma/66 & udma/100 offboard pci controllers... :\ Any help appreciated!"
You do get hotswap IDE now, but obviously the OS needs to support it. As most modern OSs don't actually use the BIOS for disk accesses (past the kernel booting), the BIOS is a non-issue.
This is being discussed on the LKML right now!
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'course, I could be wrong, but I'd imagine some of the comments in the linux kernel code might provide some hints as to how it finds the information.
If disk gometry is the only reason that the HD can not be swapped, then assuming that you have a budget, but 2 or more identical drives to swap. That way the disk is physicaly the same and all you end up changing is the contents.
Just be sure to unmount the drive first and disconnect the power cable. Then disconnect the IDE ribbon. Reverse the process with the new drive, then mount it.
If you've already got a couple of drives without mission critical data on them, you could try this. I doubt if it would damage the drives as long as you're careful. I'm not sure how Linux gets the drive's parameters, but I would guess that it can get them during the mounting, perhaps with a few command-line options if needed.
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I've had great luck with hot-swappable drives! The trick is to take your IDE devices and run over them with a large vehicle. Now make an emergency requisition of SCSI or FibreChannel devices, and all will work exactly as you were hoping.
...is to buy a SCSI RAID card and a hot swap SCSI enclosure.
If you try this kind of shit with IDE, prepare for Deep Hurting.
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"read a recent man page for hdparm and you will see kernel allows remove/add ide interface. scripts with correct parameter usage are in contrib directory of hdparm source. IDE maintainer has code to electrically turn off (tristate) ide channels on most PC ide chips, but is waiting to demonstrate at an industry conference before releasing to public." -- Jeremy Jackson
Most IDE drive trays are NOT rated for hot swap, and neither are the controllers on the motherboard. To do ide hotswap the best way is an ide raid controller from either 3ware, Promise or Adaptec along with certified disk trays.
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I haven't tried any of these enclosures, but there are some out there that claim IDE-Hot-Swap.
See this Rackmountpro example.
-sid
If you are talking about swaping out a drive that is running your OS I'd say forget it. I don't think most IDE are made for that.
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You can get IDE to ieee1394 (firewire) adapters that plug into the back of your hard drive. Now, you just get a nice firewire controller and you have a hot swapable device.
I think that the last time I checked, these controllers were around $40-50... And firewire's very cool.
Does any such command exist for standard EIDE controllers/drives? Or even in any standard Unix (preferably FreeBSD) SCSI drivers for non-FCAL drives?
Without a spin-down and disconnect, hot-swap seems like it must pose some risk, however slight.
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A while back, I had to disconnect my floppy drive to do some work inside the case. Now the system is bak up and running, but guess what? I have the ribbon cable connected to the floppy drive but the power cable is not.
Is it safe to just plug it in or do I need to power-down the system? Powering-down is a last-resort seeing the system is a server.
yes, it's possible to shutdown an ide hard drive, although I have never tried it... see the hdparm man page:
-Y Force an IDE drive to immediately enter the lowest power consumption sleep mode, causing it to shut down completely. A hard or soft reset is required before the drive can be accessed again (the Linux IDE driver will automatically handle issuing a reset if/when needed). The current power mode status can be checked using the -C flag.
If you use an external 1394/Firewire/iLink or USB hard disk, it's just an ATA disk inside. Both 1394 and USB support hot-plugging, and linux support (at least for generic devices like ATA disks) is fairly mature. As for performance, 1394 is supposedly 400 Mb (bits) per second and USB 2.0 is 480 Mb/s. You need to buy a USB 2.0 PCI card for your PC, but they aren't too much. USB 2.0 controllers are also called "EHCI". USB 2.0 devices work with USB 1.1 controllers at the standard 12 Mb/s. Search the web for "USB ATA enclosure" or "Firewire ATA enclosure" and you should find something. For portable disks, you're more likely to find USB ports on a PC, and I suspect 1394 devices are going to seem really overpriced compared to USB 2.0. But YMMV.
http://www.linux-usb.org
(you're on your own for 1394)
I know you spent money on those removable ATA caddies, but if all you want is a hot-swap ATA disk, there are other ways of getting there that are designed to do what you're after.
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