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#21
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ATA-4 (1997) standard states that all lines driven by devices shall be
tri-state (except DASP). That means anything made in the last 5 years should cause no problems to the other device if it is powered off. On my older drives, it did cause problems. "Timothy Daniels" wrote in message ... I was *not* asking about a hot-swap wherein the logical state of the drive would be undefined when powered was applied by virtue of the signal cables being pre-connected. I *was* asking about doing the switching ON/OFF of power cables while the PC was shut down. This would be logically equivalent to physically connecting and disconnecting the power cables to various HDs by opening the case, etc. I know this works in some configurations - single HDs on separate channels - because I've done it. That is, just disconnecting the power cable of one HD allows the other HD (on the other IDE channel) to boot up in isolation. |
#22
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"Timothy Daniels" wrote in message ... "chrisv" wrote: "Timothy Daniels" wrote: My question really hinges on the effect of unpowered devices connected in various combinations and configurations to a 2-device IDE cable. What would happen if the Master HD at the end of a cable were unpowered while the Slave were powered? THAT is what I don't think will work. Rod says it will, and maybe it will, for some controller/HD combinations. But it's quite hokey to do that, even if you get away with it. Hey! The whole scheme is hokey, including the removable drive tray/rack. I just want to know if it *works*. If it works, it would save a whole bunch of labor, and it would encourage me to do backups more often. Its completely mad to be using a kludge like that for backup. Makes a hell of a lot more sense to use image files instead of clones of the boot drive instead and then the whole question of how XP reacts with the clone and the original visible on the first boot after the clone has been done doesnt arise and there is no need to bother with the massive kludge of turning the power to the clone drive off for the first boot either. And if you want a physically removable drive as the destination for the backup, you'd be MUCH better off using a proper formal standard like firewire or USB2 than the monster kludge of removable drive bays anyway. |
#23
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"chrisv" wrote:
chrisv wrote: "Timothy Daniels" wrote: My question really hinges on the effect of unpowered devices connected in various combinations and configurations to a 2-device IDE cable. What would happen if the Master HD at the end of a cable were unpowered while the Slave were powered? THAT is what I don't think will work. Rod says it will, and maybe it will, for some controller/HD combinations. But it's quite hokey to do that, even if you get away with it. If the Slave were unpowered and the Master powered? If Master/Slave positions were reversed? Etc., etc. I should have noted that switched master and slave around is irrelevant to this situation. As I pointed out in a response to Rod Speed, I meant the devices at the middle connector and end connector, whatever their jumpering. That is, would a dead device at the middle impair the signaling for the end device, and would a dead device at the end impair signaling for the middle device? *TimDaniels* |
#24
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chrisv wrote in message ... Rod Speed wrote chrisv wrote Timothy Daniels wrote It would be a lot easier if one could just shut down and then disconnect the other drives by use of a physical switch to break the connection with their power cables. That would avoid all the hassle of opening the case and unplugging the other drives. So, does anyone have any information that would indicate if switching the power cables would work? I'd be very surprised if you get away with that. Having un-powered electronics connected to your bus is generally a sure-fire way to drag the bus down to nothing. It does work most of the time with removable drive bays. I'm not familiar with these... Are you saying they leave multiple drives connected to a bus, with some of those drives not powered? Yes. Most of them have a usually key operated switch which basically just turns the power off the drive in it. If you boot with the power turned off that drive, it will normally have the drive plugged into the ribbon cable still. This is why hot-swap devices, whether they are USB or whatever, have connectors that ensure that the power is applied before the signals are connected. Nope, thats for a completely different reason. Well, it allows the device's reset circuitry to bring things to a known state, as well... Thats not the reason the ground is connected first and last. Its primarily so you dont get the supply connected before the ground return. I don't think your "nope" is warranted, however. It is anyway. And what they do is ensure that GROUND is connected first on insertion and disconnected last on removal. Maybe with some hot-swapable devices, but not all. Bull****. USB clearly connects power and ground at the same time, Nope, you're ignoring the metal surround connection. as does Compact PCI (cPCI). Wrong again. You're mangling the story completely with OV there. http://www.intersil.com/data/tb/tb386.pdf http://www.quicklogic.com/images/cpci.pdf |
#25
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"Rod Speed" wrote: Its completely mad to be using a kludge like that for backup. Makes a hell of a lot more sense to use image files instead of clones of the boot drive instead and then the whole question of how XP reacts with the clone and the original visible on the first boot after the clone has been done doesnt arise and there is no need to bother with the massive kludge of turning the power to the clone drive off for the first boot either. Yes, and I intend to make image files for most backups. But I also want to have at least one bootable system ready on another drive to switch to if my primary system drive should fail. I currently keep a 2nd HD containing a bootable image running in the PC for just such an emergency. *TimDaniels* And if you want a physically removable drive as the destination for the backup, you'd be MUCH better off using a proper formal standard like firewire or USB2 than the monster kludge of removable drive bays anyway. |
#26
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Timothy Daniels wrote in message ... Rod Speed wrote Its completely mad to be using a kludge like that for backup. Makes a hell of a lot more sense to use image files instead of clones of the boot drive instead and then the whole question of how XP reacts with the clone and the original visible on the first boot after the clone has been done doesnt arise and there is no need to bother with the massive kludge of turning the power to the clone drive off for the first boot either. Yes, and I intend to make image files for most backups. But I also want to have at least one bootable system ready on another drive to switch to if my primary system drive should fail. Why ? With any decent imaging app all you have to do is boot the distribution CD or the rescue floppy and restore from an image file to the replacement drive if the primary boot drive ever does fail. I currently keep a 2nd HD containing a bootable image running in the PC for just such an emergency. Mad to be using a kludge like that for such an unlikely event. The last thing you want is to discover that you've managed to stuff up the power sequencing when you come to try to use the clone and find it wont boot. And if you want a physically removable drive as the destination for the backup, you'd be MUCH better off using a proper formal standard like firewire or USB2 than the monster kludge of removable drive bays anyway. |
#27
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Eric Gisin wrote in message ... ATA-4 (1997) standard states that all lines driven by devices shall be tri-state (except DASP). That does not say that that should happen with the drive not powered tho. That means anything made in the last 5 years should cause no problems to the other device if it is powered off. Its more complicated than that. On my older drives, it did cause problems. Just because tristate drivers werent being used. "Timothy Daniels" wrote in message ... I was *not* asking about a hot-swap wherein the logical state of the drive would be undefined when powered was applied by virtue of the signal cables being pre-connected. I *was* asking about doing the switching ON/OFF of power cables while the PC was shut down. This would be logically equivalent to physically connecting and disconnecting the power cables to various HDs by opening the case, etc. I know this works in some configurations - single HDs on separate channels - because I've done it. That is, just disconnecting the power cable of one HD allows the other HD (on the other IDE channel) to boot up in isolation. |
#28
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"Rod Speed" wrote:
Timothy Daniels wrote: Rod Speed wrote Its completely mad to be using a kludge like that for backup. Makes a hell of a lot more sense to use image files instead of clones of the boot drive instead and then the whole question of how XP reacts with the clone and the original visible on the first boot after the clone has been done doesnt arise and there is no need to bother with the massive kludge of turning the power to the clone drive off for the first boot either. Yes, and I intend to make image files for most backups. But I also want to have at least one bootable system ready on another drive to switch to if my primary system drive should fail. Why ? With any decent imaging app all you have to do is boot the distribution CD or the rescue floppy and restore from an image file to the replacement drive if the primary boot drive ever does fail. And then what, isolate the resulting bootable image for its first boot up? Then open the case again and reconnect the HDs and reboot? Why not have all that already done? I want the switchover to be as simple and quick as possible. My current practices promise that. All I want to do is to simplify the HD cloning in preparation for a inoportune primary HD failure. I currently keep a 2nd HD containing a bootable image running in the PC for just such an emergency. Mad to be using a kludge like that for such an unlikely event. The last thing you want is to discover that you've managed to stuff up the power sequencing when you come to try to use the clone and find it wont boot. An unlikely event is exactly what I'm preparing for - the same reason that I have fire insurance on my home. I have the clone already on the 2nd HD in the PC and powered up - ready to boot after a quick change in the BIOS' boot sequence. The power "sequencing" via manual switch is only meant to facilitate *making* the bootable image, not to put it into operation. If I had the money and space, I'd have a 2nd computer running in tandem, getting exactly the same input and doing exactly the same things that my current computer is doing. But what I do now is a satisfactory approximation to that. And if you want a physically removable drive as the destination for the backup, you'd be MUCH better off using a proper formal standard like firewire or USB2 than the monster kludge of removable drive bays anyway. Why? Those external HDs are more costly and slower. And I've read nothing but woe in Usenet about cloning to USB2 and FireWire external drives. Furthermore, my PC would need another PCI add-in card to add USB2 and/or FireWire to it. Right now, I have 4 new Maxtor ATA/133 7200rpm HDs with 8MB caches to use. Why should I go to the hassle and greater expense to use a slower medium? Please understand that I didn't start this thread to ask for advice. I simply asked about the effects having of an unpowered device connected to an IDE cable. *TimDaniels* |
#29
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"Eric Gisin" wrote:
ATA-4 (1997) standard states that all lines driven by devices shall be tri-state (except DASP). That means anything made in the last 5 years should cause no problems to the other device if it is powered off.... By "is powered off" do you mean "has its power switched to OFF" (the power to one drive ceases while the other drive remains running), or do you mean "remains unpowered"? My question concerns the latter scenario. *TimDaniels* |
#30
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Timothy Daniels wrote in message ... Rod Speed wrote Timothy Daniels wrote Rod Speed wrote Its completely mad to be using a kludge like that for backup. Makes a hell of a lot more sense to use image files instead of clones of the boot drive instead and then the whole question of how XP reacts with the clone and the original visible on the first boot after the clone has been done doesnt arise and there is no need to bother with the massive kludge of turning the power to the clone drive off for the first boot either. Yes, and I intend to make image files for most backups. But I also want to have at least one bootable system ready on another drive to switch to if my primary system drive should fail. Why ? With any decent imaging app all you have to do is boot the distribution CD or the rescue floppy and restore from an image file to the replacement drive if the primary boot drive ever does fail. And then what, Restore from that image file to the replacement hard drive. isolate the resulting bootable image for its first boot up? Not necessary if you're restoring from an image file and not cloning. Then open the case again and reconnect the HDs and reboot? You have to open the case to replace the boot drive thats failed. Why not have all that already done? Because removable drive bays are a kludge that sometimes work and sometimes dont and trying to turn the power off to one drive for the first boot after a clone used for a backup is an even worse kludge. You dont need any of that if you image the boot drive to an external USB2 or firewire drive for backup. I want the switchover to be as simple and quick as possible. Mindlessly silly when boot drive failure is so rare. My current practices promise that. Like hell they do when you have to fart around disconnecting the power to the clone for the first boot after the clone is made for backup. If you are stupid enough to use removable drive bays, you can just remove the clone for the first boot after the clone. All I want to do is to simplify the HD cloning in preparation for a inoportune primary HD failure. And are just making life hard for yourself in the backup process when it makes much more sense to do what doesnt require any kludge at all in the backup process and only requires a restore to the replacement hard drive in the MUCH rarer event of a boot drive failure. I currently keep a 2nd HD containing a bootable image running in the PC for just such an emergency. Mad to be using a kludge like that for such an unlikely event. The last thing you want is to discover that you've managed to stuff up the power sequencing when you come to try to use the clone and find it wont boot. An unlikely event is exactly what I'm preparing for - the same reason that I have fire insurance on my home. Yes, but it doesnt make any sense to try to minimise the TIME TO HANDLE THE BOOT DRIVE FAILURE, what makes much more sense is to minimise THE TIME TO DO THE BACKUP AND TO NOT KLUDGE THAT PROCESS. I have the clone already on the 2nd HD in the PC and powered up - ready to boot after a quick change in the BIOS' boot sequence. In the rare event that the boot drive fails. No need for that to be as quick as possible. The power "sequencing" via manual switch is only meant to facilitate *making* the bootable image, not to put it into operation. Duh. If I had the money and space, I'd have a 2nd computer running in tandem, getting exactly the same input and doing exactly the same things that my current computer is doing. But what I do now is a satisfactory approximation to that. Nope, its a collosal kludge that may well fang you on the arse if the boot drive does actually fail and you discover that you havent actually made the clone properly. And if you want a physically removable drive as the destination for the backup, you'd be MUCH better off using a proper formal standard like firewire or USB2 than the monster kludge of removable drive bays anyway. Why? Because those follow a proper standard and arent a collosal kludge. Those external HDs are more costly and slower. The speed is irrelevant when only a fool cares about how long the image file creation takes. And I've read nothing but woe in Usenet about cloning to USB2 and FireWire external drives. Your deficiencys are your problem. And you dont CLONE to them, you WRITE AN IMAGE FILE TO THEM. Furthermore, my PC would need another PCI add-in card to add USB2 and/or FireWire to it. Hardly what you might call the end of civilisation as we know it. Right now, I have 4 new Maxtor ATA/133 7200rpm HDs with 8MB caches to use. Why should I go to the hassle and greater expense to use a slower medium? Because they aint a collosal kludge that might work and might well fang you on the arse when you need to use the clone. Please understand that I didn't start this thread to ask for advice. I simply asked about the effects having of an unpowered device connected to an IDE cable. You have always been, and always will be, completely and utterly irrelevant. In spades when you cant even manage to work out the basics. |
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