Re: Booting to root on gmirror with disk failure, is it even possible?
Modulok schrieb: Before I invest significantly more time into my current gmirror issues, I have but two simple questions for anyone out there: 1. Has anyone used gmirror for the root partition and been able to successfully boot with one failed (or un-plugged) disk? It's the latter part of the question that is the real issue for me. I'm just looking for a confirmed it's possible. Yes, it is possible. IBM xSeries 346, FreeBSD 6.2-RELEASE, amd64. U360 hard drives. More specs are available from IBM. Using gmirror because we only have an Adaptec HostRAID (aka FakeRAID) controller and not a real ServerRaid, i.e. our SCSI controller basically has no useful RAID capabilities built in. My test case is to unplug any one disk while the system is running. (Don't do this with your system unless your hardware is specified for hot plugging!). FreeBSD detects a bus reset, marks the gmirror as degraded and continues operating normally, and I can also reboot the degraded gmirror without any problems. The more conservative test case is to power down the system, unplug any one disk, and restart the system. No problems with that either. In fact, the absolutely robust behaviour of gmirror was one of my key arguments for switching from Linux to FreeBSD :-). Of course there are a zillion ways to fail your hard disk, and there could be cases where one hard disk might start behaving erratically, and gmirror might not be able to detect all such cases and might try to continue using the failed disk. This could theoretically lead to some nasty data integrity issues in the worst case. But this is true for any RAID, even when implemented in hardware IMO. Regards Tobias -- Universität Stuttgart|Fakultät für Architektur und Stadtplanung|casinoIT 70174 Stuttgart Geschwister-Scholl-Straße 24D T +49 (0)711 121-4228 F +49 (0)711 121-4276 E [EMAIL PROTECTED] I http://www.casino.uni-stuttgart.de ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Booting to root on gmirror with disk failure, is it even possible?
On Sep 4, 2007, at 9:31 PMSep 4, 2007, Modulok wrote: Before I invest significantly more time into my current gmirror issues, I have but two simple questions for anyone out there: 1. Has anyone used gmirror for the root partition and been able to successfully boot with one failed (or un-plugged) disk? It's the latter part of the question that is the real issue for me. I'm just looking for a confirmed it's possible. 2. If yes, what version of FreeBSD, what brand/model of hard disks, and what mainboard was used? We have been using gmirror on some Dell systems for a while now, and we put it through it's paces before we deployed it to production. We pulled drives while the system was running, rebooted, the works. We found gmirror to be pretty fault tolerant and were not able to get it to fail. If you pull your main drive, the system was always able to successfully boot from the second drive. Rebuilding was always possible, as well. Our tests were done on older Dell PowerEdge 1650's with Fujitsu SCSI drives. I don't know specifically what model/manufacturer the motherboard is. If there's any other questions, feel free to ask! - Eric F Crist Secure Computing Networks ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Booting to root on gmirror with disk failure, is it even possible?
Before I invest significantly more time into my current gmirror issues, I have but two simple questions for anyone out there: 1. Has anyone used gmirror for the root partition and been able to successfully boot with one failed (or un-plugged) disk? It's the latter part of the question that is the real issue for me. I'm just looking for a confirmed it's possible. 2. If yes, what version of FreeBSD, what brand/model of hard disks, and what mainboard was used? Thanks. -Modulok- ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Booting to root on gmirror with disk failure, is it even possible?
1. Has anyone used gmirror for the root partition and been able to successfully boot with one failed (or un-plugged) disk? It's the latter part of the question that is the real issue for me. I'm just looking for a confirmed it's possible. yes it is. but with unplugged, with failed it may not work, depend how disk is failed 2. If yes, what version of FreeBSD, what brand/model of hard disks, and what mainboard was used? any. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: root on gmirror and disk failure...
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Modulok wrote: The provider, /dev/mirror/gm0, is not being created. This is significant for obvious reasons: no mirror means no provider which means no root. The module /boot/kernel/geom_mirror.ko is loaded, as I have manually loaded it via the loader(8) prompt and attempted the simulated failure again with identical results. It's the provider that isn't being created, for whatever reason. Suggestions? (Other than purchasing a hardware RAID card). I've seen these symptoms before. It appears to be a feature of certain Motherboards. If you're lucky there will be some BIOS options you can toggle to make it behave better -- usually to do will telling the motherboard *not* to do any sort of RAID stuff itself. Otherwise, look for BIOS updates, or switch to a different Motherboard. Systems supplied with hot swap drives (meaning SATA rather than IDE) tend to work better. Or install a hardware RAID controller. I've also a feeling that there's a behavioural difference between 'only one drive present' and 'one working drive and a blank disk' but haven't really tested that theory out, as we solved the original problem by other means. Cheers, Matthew - -- Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.4 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFG2m6/8Mjk52CukIwRCM/SAJ9paSYYdKjY4USerNYDCSKKPtjHUACfRNID nDHwMgpGUrWa5q2h2y+rASw= =9AW5 -END PGP SIGNATURE- ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
root on gmirror and disk failure...
BACKGROUND I'm experimenting with gmirror on the root partition on a test system running FreeBSD 6.1-RELEASE. I have two physical disks on the same IDE header (master and slave). This was setup following the tutorial in the handbook. The system boots and mounts root from /dev/mirror/gm0s1a as expected. The reported status of the mirror was active, complete, up and running with both disks synced. Everything is as it should be. PROBLEM When I simulate a disk failure on the slave drive (the first consumer in the mirror), by disconnecting the power input and booting the system, the following occurs: 1. The BIOS complains of a disk error, but otherwise continues to boot. 2. The master boot record is found and boot is executed. 3. boot complains, letting me know the default disk it boots from is gone and prompts for manual specification. This is fine and I specify the alternate disk to boot from. 4. loader(8) is found and presents its menu, it starts the automatic boot sequence with the default kernel. 5. It successfully finds the kernel and executes it. 6. The kernel output Trying to mount root from ufs:/dev/mirror/gm0s1a, fails and I am prompted for the location of a root partition. I digress just a moment here as the system appears to hang, as keyboard input is not detected and at this point on the boot phase I have no other metric from which to judge whether it is actually hanged or not. The keyboard was detected prior to this failure, as reported in the kernel's output and the keyboard is known to work on this system. So that's weird, but it even if I could type in something, it wouldn't matter because it's looking in the correct location for root, it's just that location doesn't exist...moving right along. The provider, /dev/mirror/gm0, is not being created. This is significant for obvious reasons: no mirror means no provider which means no root. The module /boot/kernel/geom_mirror.ko is loaded, as I have manually loaded it via the loader(8) prompt and attempted the simulated failure again with identical results. It's the provider that isn't being created, for whatever reason. Suggestions? (Other than purchasing a hardware RAID card). -Modulok- ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
