Re: Unable to shutdown
On Mon, Aug 29, 2011 at 1:06 PM, Eli Dart d...@es.net wrote: On 8/28/11 1:06 PM, Bengt Ahlgren wrote: Kevin Obermankob6...@gmail.com writes: I've run into an odd problem with dismounting file systems on a Seagate Expansion portable USB drive. Running 8-stable on an amd64 system and with two FAT32 (msdosfs) file systems on the drive. The drive is green and spins down when idle. If an attempt is made to shutdown the system while the drive is spun down, the system goes through the usual shutdown including flushing all buffer out to disk, but when the final disk access to mark the file systems as clean, the drive never spins up and the system hangs until it is powered down. I've found no way to avoid this other then to remember to access the disk and cause it to spin up before shutting down. If I attempt to unmount the file systems when the drive is shut down. the same thing happens, but I can recover as the second file system is still mounted and an ls(1) to that file system will cause the disk to spin up and everything is fine. This looks like a bug, but I don't see why the unmounting of an msdosfs system does not spin up the drive. It's clearly hanging on some operation that is not spinning up the drive, but does block. Any ideas what is going on? Possible fix? Not a solution to your problem, but a data point: I have a WD Passport 750GB (2.5) drive with an UFS filesystem on it. I don't think I've tried shutdown with the drive mounted, but I've experienced no problems after the drive has spun down, including umount. There is just a delay while it spins up. This is on 8.2-REL/i386, that is, with the new USB stack. In my experience, the issues don't show up at lower capacities. I've seen problems with 2TB drives, but 1TB and 1.5TB drives seem to work fine. Kevin - how big is the disk in question? Only 750G. It's just a little portable drive and not even a new one. It was big back when I bought it, but not any more. I think it might be more of an issue with the particular firmware on the drive. Some CAM operation seems to never complete when the drive is spun down. Either: 1. The command cannot be completed with until the drive is spun up, but a firmware bug is not triggering a spin-up or: 2. The command does not need the drive spun up, but a bug in the firmware is not allowing the completion wen the drive is not spinning. The more I look at this, the more it seems to me that it is an issue with the Seagate drive and not a FreeBSD issue. Probably a bug that is never triggered on Windows, so is largely unnoticed. I suspect Widows probably orders the command is a subtly different order. It is probably an issue that FreeBSD fails to ever timeout when this happens, though. That makes me suspect that the command in question is one that should always return something immediately. I suppose it is also possible that it is some oddity in the USB stack, too, but I still suspect that the root issue is a firmware bug in the drive. -- R. Kevin Oberman, Network Engineer - Retired E-mail: kob6...@gmail.com ___ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to freebsd-stable-unsubscr...@freebsd.org
Re: Unable to shutdown
On Tue, August 30, 2011 11:50, Kevin Oberman wrote: [...] The more I look at this, the more it seems to me that it is an issue with the Seagate drive and not a FreeBSD issue. Probably a bug that is never triggered on Windows, so is largely unnoticed. I suspect Widows probably orders the command is a subtly different order. [...] Or not the drive per se, but the USB-to-IDE/SATA chipset. A while back on the OpenSolaris zfs-discuss list there was an issue where USB drives would have corrupt ZFS pools if a drive was yanked without a 'zpool export' being run. Even though ZFS is supposed to always be consistent on-disk (because it's transactional), this wasn't happening. It turned that the chipset had a list of particular SATA commands that it allowed through to the drive, and all others were simply answered with OK, regardless of what actual actions needed to be taken. One of the SATA commands that was NOT whitelisted was the 'cache flush' command--which ZFS needs to make sure that it's data structures were written in the proper order. Turns out the drive and its firmware were fine and doing things properly, it's just that the necessary commands weren't getting to it because of the USB adaptor's chipsset. ___ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to freebsd-stable-unsubscr...@freebsd.org
Re: Unable to shutdown
On Tue, Aug 30, 2011 at 01:29:02PM -0400, David Magda wrote: On Tue, August 30, 2011 11:50, Kevin Oberman wrote: [...] The more I look at this, the more it seems to me that it is an issue with the Seagate drive and not a FreeBSD issue. Probably a bug that is never triggered on Windows, so is largely unnoticed. I suspect Widows probably orders the command is a subtly different order. [...] Or not the drive per se, but the USB-to-IDE/SATA chipset. A while back on the OpenSolaris zfs-discuss list there was an issue where USB drives would have corrupt ZFS pools if a drive was yanked without a 'zpool export' being run. Even though ZFS is supposed to always be consistent on-disk (because it's transactional), this wasn't happening. It turned that the chipset had a list of particular SATA commands that it allowed through to the drive, and all others were simply answered with OK, regardless of what actual actions needed to be taken. One of the SATA commands that was NOT whitelisted was the 'cache flush' command--which ZFS needs to make sure that it's data structures were written in the proper order. Turns out the drive and its firmware were fine and doing things properly, it's just that the necessary commands weren't getting to it because of the USB adaptor's chipsset. I don't think that advice is applicable in this situation. Here's why: Kevin's original description indicates that when the drive (or enclosure translation ASIC for that matter) is in standby, when the system is shut down, the drive/ASIC never spins back up on I/O (flushing all I/O buffers to disk). If he issues ls commands or similar userland-induced I/O to the drive prior to shutting the system down, the drive/ASIC spins up normally. Here's Kevin's original quote: The drive is green and spins down when idle. If an attempt is made to shutdown the system while the drive is spun down, the system goes through the usual shutdown including flushing all buffer out to disk, but when the final disk access to mark the file systems as clean, the drive never spins up and the system hangs until it is powered down. I've found no way to avoid this other then to remember to access the disk and cause it to spin up before shutting down. If I attempt to unmount the file systems when the drive is shut down. the same thing happens, but I can recover as the second file system is still mounted and an ls(1) to that file system will cause the disk to spin up and everything is fine. So the question is what's unique about flushing all I/O buffers to disk during shutdown compared to issuing standard I/O in userland. I can speculate all day as to what the cause is, but it's highly unlikely that the USB-to-SATA controller ASIC is causing the problem. Furthermore, Windows doesn't have special disk/enclosure drivers for such drives, so there's nothing unique Windows would be sending across the wire, ATA-protocol-wise, that would explain why Windows works and FreeBSD doesn't. At least that's my opinion. With ATA/SATA, the FLUSH CACHE (0xe7) and -EXT (0xea) (for 48-bit LBAs) commands are separate from WRITE DMA (0xca) and -EXT (0x35) (for 48-bit LBAs). Both FLUSH CACHE commands do not take LBAs in their input CDB. To flush buffers to disk I imagine what the kernel should be doing is issuing WRITE commands followed by FLUSH CACHE. The WRITEs should be waking the drive up. But wait, there's more. I want to point out to people that sleep and standby are two very different things (they're separate ATA commands too). So if you're using camcontrol sleep you probably should be using camcontrol standby. The man page is quite clear about the repercussions of the former (and in the latter case I can imagine I/O to the drive failing or simply timing out given that a bus reset is not performed during shutdown TMK). -- | Jeremy Chadwickjdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, US | | Making life hard for others since 1977. PGP 4BD6C0CB | ___ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to freebsd-stable-unsubscr...@freebsd.org
Re: Unable to shutdown
On Tue, Aug 30, 2011 at 2:48 PM, Jeremy Chadwick free...@jdc.parodius.com wrote: On Tue, Aug 30, 2011 at 01:29:02PM -0400, David Magda wrote: On Tue, August 30, 2011 11:50, Kevin Oberman wrote: [...] The more I look at this, the more it seems to me that it is an issue with the Seagate drive and not a FreeBSD issue. Probably a bug that is never triggered on Windows, so is largely unnoticed. I suspect Widows probably orders the command is a subtly different order. [...] Or not the drive per se, but the USB-to-IDE/SATA chipset. A while back on the OpenSolaris zfs-discuss list there was an issue where USB drives would have corrupt ZFS pools if a drive was yanked without a 'zpool export' being run. Even though ZFS is supposed to always be consistent on-disk (because it's transactional), this wasn't happening. It turned that the chipset had a list of particular SATA commands that it allowed through to the drive, and all others were simply answered with OK, regardless of what actual actions needed to be taken. One of the SATA commands that was NOT whitelisted was the 'cache flush' command--which ZFS needs to make sure that it's data structures were written in the proper order. Turns out the drive and its firmware were fine and doing things properly, it's just that the necessary commands weren't getting to it because of the USB adaptor's chipsset. I don't think that advice is applicable in this situation. Here's why: Kevin's original description indicates that when the drive (or enclosure translation ASIC for that matter) is in standby, when the system is shut down, the drive/ASIC never spins back up on I/O (flushing all I/O buffers to disk). If he issues ls commands or similar userland-induced I/O to the drive prior to shutting the system down, the drive/ASIC spins up normally. Here's Kevin's original quote: The drive is green and spins down when idle. If an attempt is made to shutdown the system while the drive is spun down, the system goes through the usual shutdown including flushing all buffer out to disk, but when the final disk access to mark the file systems as clean, the drive never spins up and the system hangs until it is powered down. I've found no way to avoid this other then to remember to access the disk and cause it to spin up before shutting down. If I attempt to unmount the file systems when the drive is shut down. the same thing happens, but I can recover as the second file system is still mounted and an ls(1) to that file system will cause the disk to spin up and everything is fine. So the question is what's unique about flushing all I/O buffers to disk during shutdown compared to issuing standard I/O in userland. I can speculate all day as to what the cause is, but it's highly unlikely that the USB-to-SATA controller ASIC is causing the problem. You are perhaps assuming a bit too much. Since I know that a disk read or write WILL spin up the drive, I can only assume that the msdosfs is not finding anything to flush, so is not writing. I see the full flushing all buffers countdown and it always runs successfully to zero. This, without the drive spinning up. This begs at least the question of whether the drive is receiving any writes or whether the writes are simply being cached by the drive to save energy. I suspect that the drive only spins up when enough of its write cache is filled. In that case, the flush cache might actually be what is issued, but I can't claim any certainly about that. I'm not willing to completely clear the USB-SATA chip as the culprit. Furthermore, Windows doesn't have special disk/enclosure drivers for such drives, so there's nothing unique Windows would be sending across the wire, ATA-protocol-wise, that would explain why Windows works and FreeBSD doesn't. At least that's my opinion. This is not always quite true, but it is true for the general case. (I know some WD enclosures do install a custom driver.) With ATA/SATA, the FLUSH CACHE (0xe7) and -EXT (0xea) (for 48-bit LBAs) commands are separate from WRITE DMA (0xca) and -EXT (0x35) (for 48-bit LBAs). Both FLUSH CACHE commands do not take LBAs in their input CDB. To flush buffers to disk I imagine what the kernel should be doing is issuing WRITE commands followed by FLUSH CACHE. The WRITEs should be waking the drive up. Should they? As I pointed out above, that is not necessarily the case. But wait, there's more. I want to point out to people that sleep and standby are two very different things (they're separate ATA commands too). So if you're using camcontrol sleep you probably should be using camcontrol standby. The man page is quite clear about the repercussions of the former (and in the latter case I can imagine I/O to the drive failing or simply timing out given that a bus reset is not performed during shutdown TMK). This is very interesting point. Note that when this happens, whether at shutdown or when unmounting
Re: Unable to shutdown
On Tue, Aug 30, 2011 at 04:10:13PM -0700, Kevin Oberman wrote: On Tue, Aug 30, 2011 at 2:48 PM, Jeremy Chadwick free...@jdc.parodius.com wrote: On Tue, Aug 30, 2011 at 01:29:02PM -0400, David Magda wrote: On Tue, August 30, 2011 11:50, Kevin Oberman wrote: [...] The more I look at this, the more it seems to me that it is an issue with the Seagate drive and not a FreeBSD issue. Probably a bug that is never triggered on Windows, so is largely unnoticed. I suspect Widows probably orders the command is a subtly different order. [...] Or not the drive per se, but the USB-to-IDE/SATA chipset. A while back on the OpenSolaris zfs-discuss list there was an issue where USB drives would have corrupt ZFS pools if a drive was yanked without a 'zpool export' being run. Even though ZFS is supposed to always be consistent on-disk (because it's transactional), this wasn't happening. It turned that the chipset had a list of particular SATA commands that it allowed through to the drive, and all others were simply answered with OK, regardless of what actual actions needed to be taken. One of the SATA commands that was NOT whitelisted was the 'cache flush' command--which ZFS needs to make sure that it's data structures were written in the proper order. Turns out the drive and its firmware were fine and doing things properly, it's just that the necessary commands weren't getting to it because of the USB adaptor's chipsset. I don't think that advice is applicable in this situation. ?Here's why: Kevin's original description indicates that when the drive (or enclosure translation ASIC for that matter) is in standby, when the system is shut down, the drive/ASIC never spins back up on I/O (flushing all I/O buffers to disk). If he issues ls commands or similar userland-induced I/O to the drive prior to shutting the system down, the drive/ASIC spins up normally. Here's Kevin's original quote: The drive is green and spins down when idle. ?If an attempt is made to shutdown the system while the drive is spun down, the system goes through the usual shutdown including flushing all buffer out to disk, but when the final disk access to mark the file systems as clean, the drive never spins up and the system hangs until it is powered down. I've found no way to avoid this other then to remember to access the disk and cause it to spin up before shutting down. If I attempt to unmount the file systems when the drive is shut down. the same thing happens, but I can recover as the second file system is still mounted and an ls(1) to that file system will cause the disk to spin up and everything is fine. So the question is what's unique about flushing all I/O buffers to disk during shutdown compared to issuing standard I/O in userland. ?I can speculate all day as to what the cause is, but it's highly unlikely that the USB-to-SATA controller ASIC is causing the problem. You are perhaps assuming a bit too much. Since I know that a disk read or write WILL spin up the drive, I can only assume that the msdosfs is not finding anything to flush, so is not writing. I see the full flushing all buffers countdown and it always runs successfully to zero. This, without the drive spinning up. This begs at least the question of whether the drive is receiving any writes or whether the writes are simply being cached by the drive to save energy. I suspect that the drive only spins up when enough of its write cache is filled. If there's nothing to flush, then why is the kernel indefinitely looping (finally giving up, and it usually prints something when it encounters that condition) when trying to flush buffers when the drive is spun down? What exactly is it trying to flush if there's nothing to flush? Let me ask you this: can you stop using msdosfs on said USB device and instead use UFS2 and see if the problem disappears? This is in no way a permanent solution. If this workaround fixes the problem, then I'm inclined to believe msdosfs is to blame. There have been a lot of discussion of this driver in the kernel as of late, and the general opinion of it is that it's crummy. And here's another thought: what if the issue is limited, somehow, to just writes? Meaning, could the kernel issue a false read to the device (for some random LBA, even LBA 0 for all I care) and then proceed with its write/flushing? I wonder if that would cause the drive to spin up first. That would be a quirk in my opinion. There's also the possibility the USB stack on FreeBSD is doing something really stupid... man, I don't even want to go down that road. Hans should be able to help determine if that's the case, but not using msdosfs as a test would be a good start. In that case, the flush cache might actually be what is issued, but I can't claim any certainly about that. I'm not willing to completely clear the USB-SATA chip as the culprit. I'm pretty
