Re: gjournal on compact flash
On 1/30/2010 1:35 AM, Adam Vande More wrote: There is an rc flags to automatically do a full fsck instead of backgroud, but I am unsure exactly what you mean by user intervention. Practice has shown that while softupdates handle most situations cleanly, they don't handle ALL situations. In short, having to do a blind_yes_to_all full fsck is not an option for me. OTOH a journaling solution like gjournal or softupdates journaling, makes sure that the filesystem will be surely consistent after an ungraceful power cycle. I am not in a hurry and waiting for SUJ to hit the 8 branch seems sensible. Nikos ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: gjournal on compact flash
On 1/28/2010 6:51 PM, Adam Vande More wrote: On Thu, Jan 28, 2010 at 10:42 AM, Nikos Vassiliadisnvass9...@gmx.comwrote: Hi, I am using a 40MB journal on a 500MB compact flash. Would that be sane, or I am causing more harm than good? My concerns are: 1) wear leveling. The journal is on specific part of the disk writing again and again. That should be handled by the CF itself. Though I am not sure it does a good job??? 2) I do care about ungraceful power cycles and I've seen posts on the net, mentioning: More, If you interrupt power at arbitrary times while the device is writing, you can lose the integrity of the file system being modified. The loss is not limited to the 512 byte sector being modified, as it generally is with rotating disks; you can lose an entire erase block, maybe 64K at once. I guess the above comment renders the use of a journaling filesystem useless. But, doing some naive tests, power cycling the machine while writing and checksumming the data after fsck in preen mode, revealed no error. Thanks in advance for any insights, Nikos Soft Updates seem more appropriate for a 500MB CF drive than gjournal. AFAIK, they are a wash in terms of reliability, and gjournal needs to write all data twice meaning it's slower, and increases the wear on the drive. The big drawback to soft updates is the fsck times after an unclean shutdown which really shouldn't be an issue on a 500MB drive. fsck time in my case is not an issue. What concerns me mostly is a situation where user intervention is required. The CF filesystem will be used in a embedded system and should work without user intervention. I too feel that geom journaling is not the best solution for my needs, but softupdates need more attention than gjournal. Perhaps, I should wait for SUJ, which will be in the tree soon. Nikos ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: gjournal on compact flash
On Fri, Jan 29, 2010 at 1:39 PM, Nikos Vassiliadis nvass9...@gmx.comwrote: fsck time in my case is not an issue. What concerns me mostly is a situation where user intervention is required. The CF filesystem will be used in a embedded system and should work without user intervention. I too feel that geom journaling is not the best solution for my needs, but softupdates need more attention than gjournal. Perhaps, I should wait for SUJ, which will be in the tree soon. Nikos There is an rc flags to automatically do a full fsck instead of backgroud, but I am unsure exactly what you mean by user intervention. -- Adam Vande More ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
gjournal on compact flash
Hi, I am using a 40MB journal on a 500MB compact flash. Would that be sane, or I am causing more harm than good? My concerns are: 1) wear leveling. The journal is on specific part of the disk writing again and again. That should be handled by the CF itself. Though I am not sure it does a good job??? 2) I do care about ungraceful power cycles and I've seen posts on the net, mentioning: More, If you interrupt power at arbitrary times while the device is writing, you can lose the integrity of the file system being modified. The loss is not limited to the 512 byte sector being modified, as it generally is with rotating disks; you can lose an entire erase block, maybe 64K at once. I guess the above comment renders the use of a journaling filesystem useless. But, doing some naive tests, power cycling the machine while writing and checksumming the data after fsck in preen mode, revealed no error. Thanks in advance for any insights, Nikos ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: gjournal on compact flash
On Thu, Jan 28, 2010 at 10:42 AM, Nikos Vassiliadis nvass9...@gmx.comwrote: Hi, I am using a 40MB journal on a 500MB compact flash. Would that be sane, or I am causing more harm than good? My concerns are: 1) wear leveling. The journal is on specific part of the disk writing again and again. That should be handled by the CF itself. Though I am not sure it does a good job??? 2) I do care about ungraceful power cycles and I've seen posts on the net, mentioning: More, If you interrupt power at arbitrary times while the device is writing, you can lose the integrity of the file system being modified. The loss is not limited to the 512 byte sector being modified, as it generally is with rotating disks; you can lose an entire erase block, maybe 64K at once. I guess the above comment renders the use of a journaling filesystem useless. But, doing some naive tests, power cycling the machine while writing and checksumming the data after fsck in preen mode, revealed no error. Thanks in advance for any insights, Nikos Soft Updates seem more appropriate for a 500MB CF drive than gjournal. AFAIK, they are a wash in terms of reliability, and gjournal needs to write all data twice meaning it's slower, and increases the wear on the drive. The big drawback to soft updates is the fsck times after an unclean shutdown which really shouldn't be an issue on a 500MB drive. -- Adam Vande More ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
