SLUG Mailing List ArchivesSLUG Mailing List ArchivesHi Adrian, David & Slug list.Of the seven systems I look after, three have hot-swapping HDA's via a RAID5/6 drive enclosures, two systems have add-on SATAII caddies for hot-swap and the others are without hot-swapping. If your interested, and to reset your angst a little, I have been in the computing/engineering industry for 25++ years.
On the software level the OS only has to ensure that all dirty (written too) memory pages are written out to the drives and such buffering flushed, drive index tables updated and written ALL before the drive is removed. The CLI command "umount" does this within the Linux / Unix OS. The "sync" command/programming API call is another way to do this programmatically. That is all that is required.
On the hardware side, the PSU socket must ensure that power is presented to the drive before logic is connected (ground first). This is why the +12v, +5v and GND pins are usually extended about 8mm before the rest of the pins are connected. On the logic side, logic ground is the mandatory the first pin-out that is connected, together with any design "reset" or "set" pins. Additionally, the ability of the PSU to cope with demanding surges especially on +12v, +5V lines is very important, as the switching regulator may be upset by such demands. Most people wouldn't know this - that is why I mention it.
Of course, by all means - investigate and be satisfied your got all the facts, its your system that will have to "cope" with any hot- swapping PSU and logic levels.
Cheers. Grahame On 16/05/2009, at 2:06 PM, Adrian Chadd wrote:
Uhm, I'm reasonably sure there's more to hot swap than the physical and electrical connections. I'd thus do a little more research on the topic (like reading the datasheet(s) for your motherboard and SATA chipset) to ensure that the hardware supports it. There also may be a requirement for you to manually tell the OS to "detach" and "attach" disk devices. Adrian On Sat, May 16, 2009, Grahame Kelly wrote:Hi David. As long as the drive in un-mounted you can safely remove/insert a device. You just need to make sure the drive Power connections allow hot-swapping, but generally you will get away with it normally if you haven't such PSU plug h/w. Just be aware that your PSU will require better "surge" power - so if your current PSU is a bit iffy, it will probably fail in time has been my experience. Hope this helps. Cheers. GrahameFrom: david <david@xxxxxxxxxxxxx> Date: 15 May 2009 11:58:14 PM To: slug@xxxxxxxxxxx Subject: [SLUG] hot swapping hard drives I've just installed a sata hard drive bay for a second drive, the kind that has a little front door so you can slip the drive in and out. The point of installing it was to make it easy to change drives when doing backups, but I had assumed that I would have to shut down before taking the drive in or out. When I unmount it, Gnome announces that I can now remove the media, which surprised me a bit. Should I assume that this means I can safely hot swap this drive as long as it's unmounted? The nice man in the shop assured me that I needed all sorts of mobo magic to be able to do that, but of course he was talking Windows. I would hate to splat 500G of backup. Thanks,-- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html--- Xenion - http://www.xenion.com.au/ - VPS Hosting - Commercial Squid Support - - $25/pm entry-level VPSes w/ capped bandwidth charges available in WA -