Re: [LUAU] SATA hot swap - off topic
Thanks for the suggestion. What I'd really like to be able to do is just switch out backup hard drives once a month. The goal is simple data redundancy, not hardware fail-over. I'm planning on colocating a server, and I was hoping I could just umount /dev/whichever , unlock a drive tray, and reverse the process for a different drive. It just sounds too easy, though. -Jeff MonMotha wrote: Before you go trying this, make sure the SATA drivers in Linux support hot swapping. Just because the hardware supports it doesn't mean the software does (I can practically guarantee you windows will BSOD unless you tell it in advance you're going to hotswap it's drive). This is mostly useful on RAID arrays though. See the raidhotadd and raidhotremove (or is it raidhotdel?) commands. --MonMotha
Re: [LUAU] SATA hot swap - off topic
Jeff Mings wrote: Thanks for the suggestion. What I'd really like to be able to do is just switch out backup hard drives once a month. The goal is simple data redundancy, not hardware fail-over. I'm planning on colocating a server, and I was hoping I could just umount /dev/whichever , unlock a drive tray, and reverse the process for a different drive. It just sounds too easy, though. -Jeff Jeff, Have you looked at the 3ware sata raid controllers and the 3ware hard drive enclosures? Try searching 3ware at newegg. 129 for a 64-bit two channel sata raid controller. If the goal is using the drives as a backup device, I would definitely advise mirroring two drives, especially if it is offsite. Whether you use the 3ware drive enclosure, or a less expensive tray, the 3ware web admin tool makes it easy to disable a drive, unlock and remove it, and take it to another array. This is obviously more costly than what you are trying to do, but the odds of ever losing data from a failed drive are even further reduced, and the ease of use is a timesaver/moneymaker. --scott
Re: [LUAU] SATA hot swap - off topic
On Wed, 07 Jul 2004 00:19:54 -1000, Jeff Mings [EMAIL PROTECTED] wrote: Thanks for the suggestion. What I'd really like to be able to do is just switch out backup hard drives once a month. The goal is simple data redundancy, not hardware fail-over. I'm planning on colocating a server, and I was hoping I could just umount /dev/whichever , unlock a drive tray, and reverse the process for a different drive. It just sounds too easy, though. You can use hdparm to quiesce the bus. Your version of hdparm support hotswap, but no guarentees if your kernel does. http://www.redhat.com/archives/fedora-test-list/2004-March/msg01204.html Even if it does work for your kernel, I have to advise against your approach, because hotswap != removable storage. If you have wiggle room in the colo space, give firewire a fair chance. MonMotha wrote: This is mostly useful on RAID arrays though. See the raidhotadd and raidhotremove (or is it raidhotdel?) commands. I believe this only tickles the md driver and not the bus. -Vince
Re: [LUAU] SATA hot swap - off topic
can't you just use raidtools or mdadm? Vince Hoang [EMAIL PROTECTED] Sent by: [EMAIL PROTECTED] 07/07/2004 12:34 PM Please respond to Linux/Unix Advocates/Users Hawaiian community discussion list To: Linux/Unix Advocates/Users Hawaiian community discussion list luau@lists.hosef.org cc: Subject:Re: [LUAU] SATA hot swap - off topic On Wed, 07 Jul 2004 00:19:54 -1000, Jeff Mings [EMAIL PROTECTED] wrote: Thanks for the suggestion. What I'd really like to be able to do is just switch out backup hard drives once a month. The goal is simple data redundancy, not hardware fail-over. I'm planning on colocating a server, and I was hoping I could just umount /dev/whichever , unlock a drive tray, and reverse the process for a different drive. It just sounds too easy, though. You can use hdparm to quiesce the bus. Your version of hdparm support hotswap, but no guarentees if your kernel does. http://www.redhat.com/archives/fedora-test-list/2004-March/msg01204.html Even if it does work for your kernel, I have to advise against your approach, because hotswap != removable storage. If you have wiggle room in the colo space, give firewire a fair chance. MonMotha wrote: This is mostly useful on RAID arrays though. See the raidhotadd and raidhotremove (or is it raidhotdel?) commands. I believe this only tickles the md driver and not the bus. -Vince ___ LUAU@lists.hosef.org mailing list http://lists.hosef.org/cgi-bin/mailman/listinfo/luau
Re: [LUAU] SATA hot swap - off topic
Vince Hoang wrote: MonMotha wrote: This is mostly useful on RAID arrays though. See the raidhotadd and raidhotremove (or is it raidhotdel?) commands. I believe this only tickles the md driver and not the bus. Indeed it does. I was mostly giving an example of a practical use for all this hotswap stuff. hdparm -x will tristate the bus, allowing safe hotswap if the controller and drive support it (and I'm told all SATA devices are supposed to). In general, Linux doesn't really care much about hardware suddenly disappearing (though it will usually whine a bit), though it might not always see it when it reappears. hdparm -R to register the IDE device and hdparm -U to unregister it might find some use if this problem occurs. Make darn sure you've got it unmounted (and, if it's in a RAID array, it's a good idea to hotremove it, though being RAID, this is not strictly required, first) before you do this, or you WILL end up with a dirty filesystem, and the fs layer of the kernel might not immediatley notice and may even try to continue writing to the (now nonexistant) device. That's a bad thing :) I know hdparm -R, -U, and -x can be used to swap bay devices on IBM Thinkpads. --MonMotha
Re: [LUAU] SATA hot swap - off topic
Take a hard look at the hotswap cages from supermicroinexpensive and they have the special connectors where the ground lines are longer and mate first and demate last...this makes sure that the drives dont' get hit by a capacitance charge during the hotswap processthis is the major reason why hotswap cages are so expensive from brand namesthe other thing that these guys do is during the hotswap process it sends a signal to the controller(s) that a demate is in progress and aquiesces the drive in question. This is why controllers like the Adaptec and the 3Ware are quite a bit more expensive than controllers like the promise. That and dedicated RAID processorsthe DAC-960's that I use (ultra 160 scsi) have a dedicated i960 processor and battery backed ram just to handle raid functions...this is why linux sees the volume as a single drive, not multiple drives. It also dramatically reduces system overhead, since controllers like the promise offload RAID functions into the main CPU, whereas the 3Ware and the Adaptec do the processing in buss disconnect mode; thusly not drawing down the system buss for RAID functions. THis is also why stripe set rebuilds don't affect the system on such cards too. /brian chee University of Hawaii ICS Dept Advanced Network Computing Lab 1680 East West Road, POST rm 311 Honolulu, HI 96822 808-956-5797 voice, 877-284-1934 fax - Original Message - From: Vince Hoang [EMAIL PROTECTED] To: Linux/Unix Advocates/Users Hawaiian community discussion list luau@lists.hosef.org Sent: Wednesday, July 07, 2004 11:34 AM Subject: Re: [LUAU] SATA hot swap - off topic On Wed, 07 Jul 2004 00:19:54 -1000, Jeff Mings [EMAIL PROTECTED] wrote: Thanks for the suggestion. What I'd really like to be able to do is just switch out backup hard drives once a month. The goal is simple data redundancy, not hardware fail-over. I'm planning on colocating a server, and I was hoping I could just umount /dev/whichever , unlock a drive tray, and reverse the process for a different drive. It just sounds too easy, though. You can use hdparm to quiesce the bus. Your version of hdparm support hotswap, but no guarentees if your kernel does. http://www.redhat.com/archives/fedora-test-list/2004-March/msg01204.html Even if it does work for your kernel, I have to advise against your approach, because hotswap != removable storage. If you have wiggle room in the colo space, give firewire a fair chance. MonMotha wrote: This is mostly useful on RAID arrays though. See the raidhotadd and raidhotremove (or is it raidhotdel?) commands. I believe this only tickles the md driver and not the bus. -Vince ___ LUAU@lists.hosef.org mailing list http://lists.hosef.org/cgi-bin/mailman/listinfo/luau
[LUAU] SATA hot swap - off topic
SATA drives are supposed to be hot-swappable, but I've never actually tried this. Has anyone here tried this with Linux and then run fsck or other tests to check for integrity? Thanks, -Jeff
