Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
Hi! > > >Is read access safe ? > > > > Of course read-only is safe. As long as you mount the partition READ-ONLY > > nothing can happen to it in any way, your NTFS data is at least safe. > > Isn't it still theoretcially possible for the driver to send commands to the > disk controller that cause data to become overwritten, even when it's just > supposed to read that data? AFAICS, ext3 is happy to write to read-only mounted partition. So question was not completely stupid. Pavel -- I'm [EMAIL PROTECTED] "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
Hi! Is read access safe ? Of course read-only is safe. As long as you mount the partition READ-ONLY nothing can happen to it in any way, your NTFS data is at least safe. Isn't it still theoretcially possible for the driver to send commands to the disk controller that cause data to become overwritten, even when it's just supposed to read that data? AFAICS, ext3 is happy to write to read-only mounted partition. So question was not completely stupid. Pavel -- I'm [EMAIL PROTECTED] "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
At 17:03 24/01/01, Timur Tabi wrote: >** Reply to message from Anton Altaparmakov <[EMAIL PROTECTED]> on Wed, 24 Jan >2001 16:54:36 + > > > >Is read access safe ? > > > > Of course read-only is safe. As long as you mount the partition READ-ONLY > > nothing can happen to it in any way, your NTFS data is at least safe. > >Isn't it still theoretcially possible for the driver to send commands to the >disk controller that cause data to become overwritten, even when it's just >supposed to read that data? Theoretically it is also possible that all quantums in my body decide to tunnel through space-time at exactly the same time and with the exactly same direction and speed vector for exactly the same duration of time and that I am suddenly effectively teleported to the surface of the moon. (-: But that doesn't mean it's going to happen... Seriously, it is a theoretical possibility but a practical impossibility in my opinion and to the best of my knowledge of the current driver it will not communicate with any hardware directly in any way. In fact it only performs writes by dirtying buffer cache buffers which get written back by the kernel proper. ll_rw_block() never gets called directly and neither does generic_make_request() and block_write_full_page() isn't at the moment either. (Anything I missed?) Also, when you compile the driver without the write support enabled, you are almost 100% sure even a major bug in the driver will not cause any writes. And no, the driver is not a virus nor a trojan nor does it have any intelligence to suddenly decide to write things when it isn't asked to... NOTE: Please don't take my comments personally / too seriously but I couldn't resist... Follow-ups to alt.silly.* please... Regards, Anton -- "Education is what remains after one has forgotten everything he learned in school." - Albert Einstein -- Anton Altaparmakov Voice: +44-(0)1223-333541(lab) / +44-(0)7712-632205(mobile) Christ's CollegeeMail: [EMAIL PROTECTED] / [EMAIL PROTECTED] Cambridge CB2 3BUICQ: 8561279 United Kingdom WWW: http://www-stu.christs.cam.ac.uk/~aia21/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
Timur Tabi wrote: > Isn't it still theoretcially possible for the driver to send commands to the > disk controller that cause data to become overwritten, even when it's just > supposed to read that data? IMHO the NTFS driver creators weren't bloody newbies and won't do such a bug, even not by accidence. Also I think there might be a VFS protection of R/O space, but I'm not sure. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
** Reply to message from Anton Altaparmakov <[EMAIL PROTECTED]> on Wed, 24 Jan 2001 16:54:36 + > >Is read access safe ? > > Of course read-only is safe. As long as you mount the partition READ-ONLY > nothing can happen to it in any way, your NTFS data is at least safe. Isn't it still theoretcially possible for the driver to send commands to the disk controller that cause data to become overwritten, even when it's just supposed to read that data? -- Timur Tabi - [EMAIL PROTECTED] Interactive Silicon - http://www.interactivesi.com When replying to a mailing-list message, please direct the reply to the mailing list only. Don't send another copy to me. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
At 15:05 24/01/01, Cataldo Thomas wrote: >On Wed, 24 Jan 2001, Alan Cox wrote: > > 2.4.0-ac11 > > o Major NTFS updates (Anton Altaparmakov) > >Is read access safe ? Of course read-only is safe. As long as you mount the partition READ-ONLY nothing can happen to it in any way, your NTFS data is at least safe. It is possible however that the driver might cause the kernel to crash in the worst case so you might loose unsaved data on other write mounted partitions. Note that this is an infrequent event and I have only over experienced it under extreme load of the driver! Casual use like playing mp3s from an NTFS partition works fine. On a production system, leaving NTFS partitions mounted will slowly eat your memory (reported by several people), mostly it will go into buffers which don't seem to get freed (I think this is better with more recent kernels but don't have a box with NTFS partitions which can stay up for more than a day, due to needing to use windows, to make sure). - There is no detectable memory leak I can see (I wrote a small memory debugger tracking facility and added it to the driver and all allocated memory was released when the unmount happened, so there is no leak, admittedly I need to have this run for longer to make sure, also none of the memory blocks were overrun in either direction). To summarize: usage for read only is fine for general, not too heavy duty, workstation that gets rebooted once every few days, kind of use. Note that some of the facilities from Windows 2000 NTFS are not available and the driver will either ignore them or do something stupid, but it will NOT damage your data. Write mode is another matter completely! It is extremely DANGEROUS and NOT suitable for everyday use. I would recommend to never mount an NTFS partition read/write unless you are a developer and it is either a fully backed up partition which you can afford to have completely trashed OR your partition is already trashed / NT/2k isn't working and you are trying to fix it. Only then is it ok to use it. Also note that the current driver has no support whatsoever for deleting files/directories. So you can either create files or copy files on top of others but not delete any of them. And finally note that dealing with directories is not right so preferably stick to only creating/copying files without involving the creation of directories. >I would really be interested by a link to ntfs status in linux. I mean >what is safe and what is not. You will have to wait for that kind of thing I am afraid. I might put up some kind of status page up on sourceforge at some point but not now. More important things to do. If someone wants to make a web page just drop me a line and we can put it up on linux-ntfs.sourceforge.net (nothing there at the moment at all)... Hope this answers your immediate questions. Best regards, Anton -- "Programmers never die. They do a GOSUB without RETURN." - Unknown source -- Anton Altaparmakov (replace at with @) Linux NTFS Maintainer / WWW: http://sourceforge.net/projects/linux-ntfs/ ICQ: 8561279 / Home page: http://www-stu.christs.cam.ac.uk/~aia21/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
At 15:05 24/01/01, Cataldo Thomas wrote: On Wed, 24 Jan 2001, Alan Cox wrote: 2.4.0-ac11 o Major NTFS updates (Anton Altaparmakov) Is read access safe ? Of course read-only is safe. As long as you mount the partition READ-ONLY nothing can happen to it in any way, your NTFS data is at least safe. It is possible however that the driver might cause the kernel to crash in the worst case so you might loose unsaved data on other write mounted partitions. Note that this is an infrequent event and I have only over experienced it under extreme load of the driver! Casual use like playing mp3s from an NTFS partition works fine. On a production system, leaving NTFS partitions mounted will slowly eat your memory (reported by several people), mostly it will go into buffers which don't seem to get freed (I think this is better with more recent kernels but don't have a box with NTFS partitions which can stay up for more than a day, due to needing to use windows, to make sure). - There is no detectable memory leak I can see (I wrote a small memory debugger tracking facility and added it to the driver and all allocated memory was released when the unmount happened, so there is no leak, admittedly I need to have this run for longer to make sure, also none of the memory blocks were overrun in either direction). To summarize: usage for read only is fine for general, not too heavy duty, workstation that gets rebooted once every few days, kind of use. Note that some of the facilities from Windows 2000 NTFS are not available and the driver will either ignore them or do something stupid, but it will NOT damage your data. Write mode is another matter completely! It is extremely DANGEROUS and NOT suitable for everyday use. I would recommend to never mount an NTFS partition read/write unless you are a developer and it is either a fully backed up partition which you can afford to have completely trashed OR your partition is already trashed / NT/2k isn't working and you are trying to fix it. Only then is it ok to use it. Also note that the current driver has no support whatsoever for deleting files/directories. So you can either create files or copy files on top of others but not delete any of them. And finally note that dealing with directories is not right so preferably stick to only creating/copying files without involving the creation of directories. I would really be interested by a link to ntfs status in linux. I mean what is safe and what is not. You will have to wait for that kind of thing I am afraid. I might put up some kind of status page up on sourceforge at some point but not now. More important things to do. If someone wants to make a web page just drop me a line and we can put it up on linux-ntfs.sourceforge.net (nothing there at the moment at all)... Hope this answers your immediate questions. Best regards, Anton -- "Programmers never die. They do a GOSUB without RETURN." - Unknown source -- Anton Altaparmakov aia21 at cam.ac.uk (replace at with @) Linux NTFS Maintainer / WWW: http://sourceforge.net/projects/linux-ntfs/ ICQ: 8561279 / Home page: http://www-stu.christs.cam.ac.uk/~aia21/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
** Reply to message from Anton Altaparmakov [EMAIL PROTECTED] on Wed, 24 Jan 2001 16:54:36 + Is read access safe ? Of course read-only is safe. As long as you mount the partition READ-ONLY nothing can happen to it in any way, your NTFS data is at least safe. Isn't it still theoretcially possible for the driver to send commands to the disk controller that cause data to become overwritten, even when it's just supposed to read that data? -- Timur Tabi - [EMAIL PROTECTED] Interactive Silicon - http://www.interactivesi.com When replying to a mailing-list message, please direct the reply to the mailing list only. Don't send another copy to me. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
Timur Tabi wrote: Isn't it still theoretcially possible for the driver to send commands to the disk controller that cause data to become overwritten, even when it's just supposed to read that data? IMHO the NTFS driver creators weren't bloody newbies and won't do such a bug, even not by accidence. Also I think there might be a VFS protection of R/O space, but I'm not sure. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: NTFS safety and lack thereof - Was: Re: Linux 2.4.0ac11
At 17:03 24/01/01, Timur Tabi wrote: ** Reply to message from Anton Altaparmakov [EMAIL PROTECTED] on Wed, 24 Jan 2001 16:54:36 + Is read access safe ? Of course read-only is safe. As long as you mount the partition READ-ONLY nothing can happen to it in any way, your NTFS data is at least safe. Isn't it still theoretcially possible for the driver to send commands to the disk controller that cause data to become overwritten, even when it's just supposed to read that data? Theoretically it is also possible that all quantums in my body decide to tunnel through space-time at exactly the same time and with the exactly same direction and speed vector for exactly the same duration of time and that I am suddenly effectively teleported to the surface of the moon. (-: But that doesn't mean it's going to happen... Seriously, it is a theoretical possibility but a practical impossibility in my opinion and to the best of my knowledge of the current driver it will not communicate with any hardware directly in any way. In fact it only performs writes by dirtying buffer cache buffers which get written back by the kernel proper. ll_rw_block() never gets called directly and neither does generic_make_request() and block_write_full_page() isn't at the moment either. (Anything I missed?) Also, when you compile the driver without the write support enabled, you are almost 100% sure even a major bug in the driver will not cause any writes. And no, the driver is not a virus nor a trojan nor does it have any intelligence to suddenly decide to write things when it isn't asked to... NOTE: Please don't take my comments personally / too seriously but I couldn't resist... Follow-ups to alt.silly.* please... Regards, Anton -- "Education is what remains after one has forgotten everything he learned in school." - Albert Einstein -- Anton Altaparmakov Voice: +44-(0)1223-333541(lab) / +44-(0)7712-632205(mobile) Christ's CollegeeMail: [EMAIL PROTECTED] / [EMAIL PROTECTED] Cambridge CB2 3BUICQ: 8561279 United Kingdom WWW: http://www-stu.christs.cam.ac.uk/~aia21/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
