diff --git a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml index 71674e34ac..4bcdeb6a17 100644 --- a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml @@ -1,7 +1,7 @@ @@ -14,6 +14,105 @@ memory, or networked, on FreeBSD. + + BIOS Drive Numbering + + Before you install and configure FreeBSD on your system, there is an + important subject that you should be aware of if, especially if you have + multiple hard drives. + + In a PC running DOS or any of the BIOS-dependent operating systems + (WINxxx), the BIOS is able to abstract the normal disk drive order, and + the operating system goes along with the change. This allows the user + to boot from a disk drive other than the so-called primary + master. This is especially convenient for some users who have + found that the simplest and cheapest way to keep a system backup is to + buy an identical second hard drive, and perform routine copies of the + first drive to the second drive using Ghost or XCOPY. Then, if the + first drive fails, or is attacked by a virus, or is scribbled upon by an + operating system defect, he can easily recover by instructing the BIOS + to logically swap the drives. It's like switching the cables on the + drives, but without having to open the case. + + More expensive systems with SCSI controllers often include BIOS + extensions which allow the SCSI drives to be re-ordered in a similar + fashion for up to seven drives. + + A user who is accustomed to taking advantage of these features may + become surprised when the results with FreeBSD are not as expected. + FreeBSD does not use the BIOS, and does not know the logical BIOS + drive mapping. This can lead to very perplexing situations, + especially when drives are physically identical in geometry, and have + also been made as data clones of one another. + + When using FreeBSD, always restore the BIOS to natural drive + numbering before installing FreeBSD, and then leave it that way. If you + need to switch drives around, then do so, but do it the hard way, and + open the case and move the jumpers and cables. + + + An illustration from the files of Bill and Fred's Exceptional + Adventures: + + Bill breaks-down an older WIntel box to make another FreeBSD box + for Fred. Bill installs a single SCSI drive as SCSI unit zero, and + installs FreeBSD on it. + + Fred begins using the system, but after several days notices that + the older SCSI drive is reporting numerous soft errors, and reports + this fact to Bill. + + After several more days, Bill decides it's time to address the + situation, so he grabs an identical SCSI drive from the disk drive + "archive" in the back room. An initial surface scan indicates that + this drive is functioning well, so Bill installs this drive as SCSI + unit four, and makes an image copy from drive zero to drive four. Now + that the new drive is installed and functioning nicely, Bill decides + that it's a good idea to start using it, so he uses features in the + SCSI BIOS to re-order the disk drives so that the system boots from + SCSI unit four. FreeBSD boots and runs just fine. + + Fred continues his work for several days, and soon Bill and Fred + decide that it's time for a new adventure -- time to upgrade to a + newer version of FreeBSD. Bill removes SCSI unit zero because it was + a bit flakey, and replaces it with another identical disk drive from + the "archive." Bill then installs the new version of FreeBSD onto the + new SCSI unit zero using Fred's magic internet FTP floppies. The + installation goes well. + + Fred uses the new version of FreeBSD for a few days, and certifies + that it is good enough for use in the engineering department...it's + time to copy all of his work from the old version. So Fred mounts + SCSI unit four (the latest copy of the older FreeBSD version). Fred + is dismayed to find that none of his precious work is present on SCSI + unit four. + + Where did the data go? + + When Bill made an image copy of the original SCSI unit zero onto + SCSI unit four, unit four became the "new clone," When Bill + re-ordered the SCSI BIOS so that he could boot from SCSI unit four, he + was only fooling himself. FreeBSD was still running on SCSI unit zero. + Making this kind of BIOS change will cause some or all of the Boot and + Loader code to be fetched from the selected BIOS drive, but when the + FreeBSD kernel drivers take-over, the BIOS drive numbering will be + ignored, and FreeBSD will transition back to normal drive numbering. + In the illustration at hand, the system continued to operate on the + original SCSI unit zero, and all of Fred's data was there, not on SCSI + unit four. The fact that the system appeared to be running on SCSI + unit four was simply an artifact of human expectations. + + We are delighted to mention that no data bytes were killed or + harmed in any way by our discovery of this phenomenon. The older SCSI + unit zero was retrieved from the bonepile, and all of Fred's work was + returned to him, (and now Bill knows that he can count as high as + zero). + + Although SCSI drives were used in this illustration, the concepts + apply equally to IDE drives. + + + Disk Naming diff --git a/en_US.ISO8859-1/books/handbook/install/chapter.sgml b/en_US.ISO8859-1/books/handbook/install/chapter.sgml index c16349a995..1db73b7204 100644 --- a/en_US.ISO8859-1/books/handbook/install/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/install/chapter.sgml @@ -1,7 +1,7 @@ @@ -486,6 +486,15 @@ ftp:*:99:99::0:0:FTP:/cdrom:/nonexistent installation requests them. + + + Check your BIOS drive numbering + + If you have used features in your BIOS to renumber your disk + drives without recabling them then you should read first to ensure you do not + confused. + @@ -1615,3 +1624,14 @@ ftp:*:99:99::0:0:FTP:/cdrom:/nonexistent + + diff --git a/en_US.ISO_8859-1/books/handbook/disks/chapter.sgml b/en_US.ISO_8859-1/books/handbook/disks/chapter.sgml index 71674e34ac..4bcdeb6a17 100644 --- a/en_US.ISO_8859-1/books/handbook/disks/chapter.sgml +++ b/en_US.ISO_8859-1/books/handbook/disks/chapter.sgml @@ -1,7 +1,7 @@ @@ -14,6 +14,105 @@ memory, or networked, on FreeBSD. + + BIOS Drive Numbering + + Before you install and configure FreeBSD on your system, there is an + important subject that you should be aware of if, especially if you have + multiple hard drives. + + In a PC running DOS or any of the BIOS-dependent operating systems + (WINxxx), the BIOS is able to abstract the normal disk drive order, and + the operating system goes along with the change. This allows the user + to boot from a disk drive other than the so-called primary + master. This is especially convenient for some users who have + found that the simplest and cheapest way to keep a system backup is to + buy an identical second hard drive, and perform routine copies of the + first drive to the second drive using Ghost or XCOPY. Then, if the + first drive fails, or is attacked by a virus, or is scribbled upon by an + operating system defect, he can easily recover by instructing the BIOS + to logically swap the drives. It's like switching the cables on the + drives, but without having to open the case. + + More expensive systems with SCSI controllers often include BIOS + extensions which allow the SCSI drives to be re-ordered in a similar + fashion for up to seven drives. + + A user who is accustomed to taking advantage of these features may + become surprised when the results with FreeBSD are not as expected. + FreeBSD does not use the BIOS, and does not know the logical BIOS + drive mapping. This can lead to very perplexing situations, + especially when drives are physically identical in geometry, and have + also been made as data clones of one another. + + When using FreeBSD, always restore the BIOS to natural drive + numbering before installing FreeBSD, and then leave it that way. If you + need to switch drives around, then do so, but do it the hard way, and + open the case and move the jumpers and cables. + + + An illustration from the files of Bill and Fred's Exceptional + Adventures: + + Bill breaks-down an older WIntel box to make another FreeBSD box + for Fred. Bill installs a single SCSI drive as SCSI unit zero, and + installs FreeBSD on it. + + Fred begins using the system, but after several days notices that + the older SCSI drive is reporting numerous soft errors, and reports + this fact to Bill. + + After several more days, Bill decides it's time to address the + situation, so he grabs an identical SCSI drive from the disk drive + "archive" in the back room. An initial surface scan indicates that + this drive is functioning well, so Bill installs this drive as SCSI + unit four, and makes an image copy from drive zero to drive four. Now + that the new drive is installed and functioning nicely, Bill decides + that it's a good idea to start using it, so he uses features in the + SCSI BIOS to re-order the disk drives so that the system boots from + SCSI unit four. FreeBSD boots and runs just fine. + + Fred continues his work for several days, and soon Bill and Fred + decide that it's time for a new adventure -- time to upgrade to a + newer version of FreeBSD. Bill removes SCSI unit zero because it was + a bit flakey, and replaces it with another identical disk drive from + the "archive." Bill then installs the new version of FreeBSD onto the + new SCSI unit zero using Fred's magic internet FTP floppies. The + installation goes well. + + Fred uses the new version of FreeBSD for a few days, and certifies + that it is good enough for use in the engineering department...it's + time to copy all of his work from the old version. So Fred mounts + SCSI unit four (the latest copy of the older FreeBSD version). Fred + is dismayed to find that none of his precious work is present on SCSI + unit four. + + Where did the data go? + + When Bill made an image copy of the original SCSI unit zero onto + SCSI unit four, unit four became the "new clone," When Bill + re-ordered the SCSI BIOS so that he could boot from SCSI unit four, he + was only fooling himself. FreeBSD was still running on SCSI unit zero. + Making this kind of BIOS change will cause some or all of the Boot and + Loader code to be fetched from the selected BIOS drive, but when the + FreeBSD kernel drivers take-over, the BIOS drive numbering will be + ignored, and FreeBSD will transition back to normal drive numbering. + In the illustration at hand, the system continued to operate on the + original SCSI unit zero, and all of Fred's data was there, not on SCSI + unit four. The fact that the system appeared to be running on SCSI + unit four was simply an artifact of human expectations. + + We are delighted to mention that no data bytes were killed or + harmed in any way by our discovery of this phenomenon. The older SCSI + unit zero was retrieved from the bonepile, and all of Fred's work was + returned to him, (and now Bill knows that he can count as high as + zero). + + Although SCSI drives were used in this illustration, the concepts + apply equally to IDE drives. + + + Disk Naming diff --git a/en_US.ISO_8859-1/books/handbook/install/chapter.sgml b/en_US.ISO_8859-1/books/handbook/install/chapter.sgml index c16349a995..1db73b7204 100644 --- a/en_US.ISO_8859-1/books/handbook/install/chapter.sgml +++ b/en_US.ISO_8859-1/books/handbook/install/chapter.sgml @@ -1,7 +1,7 @@ @@ -486,6 +486,15 @@ ftp:*:99:99::0:0:FTP:/cdrom:/nonexistent installation requests them. + + + Check your BIOS drive numbering + + If you have used features in your BIOS to renumber your disk + drives without recabling them then you should read first to ensure you do not + confused. + @@ -1615,3 +1624,14 @@ ftp:*:99:99::0:0:FTP:/cdrom:/nonexistent + +