Safe to bypass fsck?
in [Solaris]
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From: Mr. Nice Guy on 22 Apr 2010 12:30 Hi. I have a Solaris 10 system with a partition that has journaling turned off - that's the way the admin originally set it up. Recently, this system booted and stopped before loading the OS, prompting with "Type control-d to proceed with normal startup, (or give root password for system maintenance)". Typically, I would login as root and run fsck on the partition to fix it. But another guy says I don't need to do that. He said that what he does is type the <stop-a> sequence to get the OBP prompt, and then does a "reset-all", and that, according to him, fixes the problem with the file-system. That goes against logic, and experience, so I wanted to get a third perspective to see what others think.
From: Colin B. on 22 Apr 2010 15:28 Mr. Nice Guy <aaron(a)mcs-partners.com> wrote: > Hi. I have a Solaris 10 system with a partition that has journaling > turned off - that's the way the admin originally set it up. Recently, > this system booted and stopped before loading the OS, prompting with > "Type control-d to proceed with normal startup, (or give root > password for system maintenance)". > > Typically, I would login as root and run fsck on the partition to fix > it. But another guy says I don't need to do that. He said that what he > does is type the <stop-a> sequence to get the OBP prompt, and then > does a "reset-all", and that, according to him, fixes the problem with > the file-system. That goes against logic, and experience, so I wanted > to get a third perspective to see what others think. With journalling turned off, you will definitely want to do an fsck. Breaking and rebooting will cause more problems, not fix them. It *may* be able to hide filesystem corruption, so you're not as healthy as you think. That's not a good thing. The "other guy" is an idiot who doesn't know what he's doing. Ignore him. Colin
From: Ian Collins on 22 Apr 2010 15:56 On 04/23/10 07:28 AM, Colin B. wrote: > Mr. Nice Guy<aaron(a)mcs-partners.com> wrote: >> Hi. I have a Solaris 10 system with a partition that has journaling >> turned off - that's the way the admin originally set it up. Recently, >> this system booted and stopped before loading the OS, prompting with >> "Type control-d to proceed with normal startup, (or give root >> password for system maintenance)". >> >> Typically, I would login as root and run fsck on the partition to fix >> it. But another guy says I don't need to do that. He said that what he >> does is type the<stop-a> sequence to get the OBP prompt, and then >> does a "reset-all", and that, according to him, fixes the problem with >> the file-system. That goes against logic, and experience, so I wanted >> to get a third perspective to see what others think. > > With journalling turned off, you will definitely want to do an fsck. > Breaking and rebooting will cause more problems, not fix them. It *may* > be able to hide filesystem corruption, so you're not as healthy as you > think. That's not a good thing. > > The "other guy" is an idiot who doesn't know what he's doing. Ignore him. Once you've done that, fix the fs then upgrade to ZFS! -- Ian Collins
From: Richard B. Gilbert on 22 Apr 2010 17:25 Colin B. wrote: > Mr. Nice Guy <aaron(a)mcs-partners.com> wrote: >> Hi. I have a Solaris 10 system with a partition that has journaling >> turned off - that's the way the admin originally set it up. Recently, >> this system booted and stopped before loading the OS, prompting with >> "Type control-d to proceed with normal startup, (or give root >> password for system maintenance)". >> >> Typically, I would login as root and run fsck on the partition to fix >> it. But another guy says I don't need to do that. He said that what he >> does is type the <stop-a> sequence to get the OBP prompt, and then >> does a "reset-all", and that, according to him, fixes the problem with >> the file-system. That goes against logic, and experience, so I wanted >> to get a third perspective to see what others think. > > With journalling turned off, you will definitely want to do an fsck. > Breaking and rebooting will cause more problems, not fix them. It *may* > be able to hide filesystem corruption, so you're not as healthy as you > think. That's not a good thing. > > The "other guy" is an idiot who doesn't know what he's doing. Ignore him. > > Colin Is there some reason not to turn on journaling? Journaling can make things run slower. Basically it writes "I'm going to update block 24,736" to a file, does the update and, on successful completion, deletes the "I'm going to update. . . ." and is done. If the system crashes while doing the update it reboots and finds that it was in the process of doing an update, had not completed it, and applies the failed transaction. Your choices are to have the system do this extra bookkeeping and be relatively bullet proof, or to have your updates run a little faster with no guarantee that they will get done properly. If power is not too stable and you don't have a UPS, journaling can save you a good deal of work. Or, you can have slightly better performance at the price of having to fsck a file system at inconvenient times. I used to hate having to to wake up at 3:37 AM to clean up after a power outrage. Where possible, I used journaling.
From: Colin B. on 23 Apr 2010 15:29
Richard B. Gilbert <rgilbert88(a)comcast.net> wrote: > Colin B. wrote: .... >> With journalling turned off, you will definitely want to do an fsck. >> Breaking and rebooting will cause more problems, not fix them. It *may* >> be able to hide filesystem corruption, so you're not as healthy as you >> think. That's not a good thing. >> >> The "other guy" is an idiot who doesn't know what he's doing. Ignore him. >> >> Colin > > Is there some reason not to turn on journaling? > > Journaling can make things run slower. Basically it writes "I'm going > to update block 24,736" to a file, does the update and, on successful > completion, deletes the "I'm going to update. . . ." and is done. If > the system crashes while doing the update it reboots and finds that it > was in the process of doing an update, had not completed it, and applies > the failed transaction. I noticed that the OP was not using logging, which is why I mentioned it. Years ago, when logging first became available, it could be very slow in some circumstances, due (mostly) to bugs. I haven't seen that for ages though. I'd say that if you're so close to the edge that you need the performance gain from disabling logging, then you're too close to the edge. I can't imagine anyone deliberately disabling logging anymore, unless they're misguided (or using ZFS). Colin |