Chip 1998 February

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FIPS Frequently Asked Questions ------------------------------- Here are some questions that people asked me by email. This file may help you with some common problems. Please read it carefully before sending mail. If you want to know what FIPS is all about, read the file README.1ST. There are answers to the following questions: Q01. Since you can split partitions with FIPS, it should also be possible to merge partitions, right? Q02. Can I reverse the changes that FIPS made to my harddisk? Q03. What if I did not keep the root and boot sector? Can I still undo the partition split? Q04. I heard that the cluster size depends on the partition size and that space usage is better with a small cluster size. Can I use FIPS to decrease the cluster size of my hard disk? Q05. I want to split a large partition into three or four smaller ones. Can I use FIPS multiple times? Q06. FIPS creates a second primary DOS partition by default. Is this allowed? Q07. What does the message "Info: Partition table inconsistency" mean? Q08. FIPS displays an error message and refuses to work. What should I do? Q09. FIPS does not recognize my SCSI disk. Q10. FIPS finds a partition with partition type 56h. Q11. FIPS seems to work fine, and DOS sees the new partition, but Linux fdisk sees only one partition. Q12. Does FIPS work with Windows 95? ------------------------------------------------------------------------------ Q01. Since you can split partitions with FIPS, it should also be possible to merge partitions, right? A01.a ----- NOT IN GENERAL. I don't want to go into technical details, just so much: Every DOS formatted partition has a file allocation table (FAT) that holds entries for every cluster of the partition. Usually one FAT is not large enough to hold the information for both partitions, so that partitions can not be easily joined. It is feasible, but I'm probably not going to incor- porate this into FIPS. So far I have heard of two software packages that claim to expand partitions. One is a free program called "Partition Resizer" (look for a file called presz???.zip on you favorite BBS or FTP server), the other is a commercial product called PartitionMagic by Powerquest. I did not try these yet. A01.b ----- YES, if you split the partitions with FIPS before. As you may expect, the problem with the FAT does not exist in that case, since it was origi- nally formatted large enough. In fact the only thing required is resto- ring the original root and boot sector (it does not matter how the data on the partition changed in the meantime). This can be done with the program 'restorrb' which comes with FIPS. Please consider the following: - You must have the original image of the root and boot sector. For this you _must_ save them to a floppy disk when FIPS offers that. - You must not format the first partition in the meantime (because then a new FAT is generated which is probably too small). - The data on the second partition (the one that was generated by FIPS) is lost, of course. The data on the first partition is preserved. --------- Q02. Can I reverse the changes that FIPS made to my harddisk? A02. ---- Yes, see answer A01.b. Make sure that you keep the original root and boot sectors that you can save to floppy disk with FIPS. --------- Q03. What if I did not keep the root and boot sector? Can I still undo the partition split? A03. ---- Difficult. For the moment, your only option is to read the file TECHINFO.TXT to learn about the hard disk structures, recalculate the old partition and format info by hand and use a disk editor the change them. You must roughly proceed as follows (I will call the partition that was split off of the original partition the 'second' partition, the remaining part of the original partition the 'first' one): 1. Make sure there is no important data left on the second partition, since it will be deleted. Make copies of all root and boot sectors (on floppy disk!) in case you make a mistake. Also make sure that you have a bootable DOS floppy with the disk editor on it. Backup your data! 2. Choose 'edit physical drive' and 'edit partition table' in the disk editor menu (assuming that your disk editor supports this). 3. Examine the table to make sure which two partitions you want to merge. 4. Take end head, cylinder, sector from the second partition and enter the values in the corresponding fields of the first partition. 5. Add the number of sectors of the first partition to the number of sectors of the second and enter the new value in the number of sectors field of the first partition. 6. Delete the entry for the second partition completely (overwrite with zeroes). 7. Look for the boot sector of the first partition and enter the new no. of sectors in the no. of sectors field in the boot sector. Please make sure you know what you are doing. I can't take any responsibi- lity if you mess up your hard disk. Read the TECHINFO.TXT file carefully. --------- Q04. I heard that the cluster size depends on the partition size and that space usage is better with a small cluster size. Can I use FIPS to decrease the cluster size of my hard disk? A04. ---- In the partition that you split off of the original partition, the cluster size is automatically adapted to the new size when you format it. In the original partition, you can not change the cluster size without reformat- ting and thereby deleting all data. If your new partition is big enough, you might copy the data to the new partition and format the old one, but be aware of two things: 1. You will not be able to reverse the partition split afterwards (see A1.a). 2. Newer format programs check to see if the partition has already been formatted and in this case will preserve the format (to make data re- covery easier in case the formatting was a mistake). You might have to trick the format program into thinking that the partition is new. Possibly the /u switch will do this (I have no possibility to check this, please let me know if it works), but if not, you might have to use a disk editor and overwrite the boot sector of the partition with zeroes to invalidate it. Note: I received a report that even overwriting the boot sector was not enough. I can only imagine that there was still information in the BIOS tables about the old format - I suggest to reboot after overwriting the boot sector to clear all tables. Sometimes the DOS tools are just too intelligent :-( If you experience problems here, drop me a line. The usual cluster size of a partition is roughly as follows: 0 - 32MB 512 Bytes 32 - 64MB 1024 Bytes 64 - 128MB 2048 Bytes 128 - 256MB 4096 Bytes 256 - 512MB 8192 Bytes 512 -1024MB 16384 Bytes --------- Q05. I want to split a large partition into three or four smaller ones. Can I use FIPS multiple times? A05. ---- Yes. You must format the newly created partitions between successive uses of FIPS. Regarding the cluster size, consider the following example: - Suppose you want to split a 1GB hard disk into four partitions of 256K each. - The original partition is formatted with a cluster size of 16KB. - The first split is into 256KB / 768KB. The cluster size of the first partition remains 16KB, although 4KB would be enough. It can only be changed by reformatting, see A04. - The new partition of 768KB is formatted, still with a cluster size of 16KB. - The second split is made into 256KB / 256KB / 512KB. - The third partition is formatted with a cluster size of 8KB. - The third split is made into 256KB / 256KB / 256KB / 256KB. - The fourth partition is formatted with a cluster size of 4KB. - So now you have the cluster sizes 16K - 16K - 8K - 4K. - Since the second and third partition are still empty, it is possible to reformat them to a cluster size of 4K. See A04. for details on reformatting. --------- Q06. FIPS creates a second primary DOS partition by default. Is this allowed? A06. ---- See the section 'What FIPS does' in FIPS.DOC for a discussion of this issue. --------- Q07. What does the message "Info: Partition table inconsistency" mean? A07. ---- The partition table in the master boot record (root sector) consists of four entries with several fields each. The strange thing about this table is that some of the fields are redundant. Look here: | | Start | | End | Start |Number of| Part.|bootable|Head Cyl. Sector|System|Head Cyl. Sector| Sector |Sectors | MB -----+--------+----------------+------+----------------+--------+---------+---- 1 | yes | 0 148 1| 83h| 15 295 63| 149184| 149184| 72 2 | no | 1 0 1| 06h| 15 139 63| 63| 141057| 68 3 | no | 0 140 1| 06h| 15 147 63| 141120| 8064| 3 4 | no | 0 0 0| 00h| 0 0 0| 0| 0| 0 The start and end (head/cylinder/sector) values can be calculated from the start sector and number of sectors (after inquiring the BIOS about the number of heads and number of sectors per track), and in fact that's exactly what DOS does. These field are completely unused by DOS (and every other OS that I know of), so they could as well be set to all zeroes. It does however not hurt to keep them in a consistent state. When fdisk creates a partition table entry, it should enter the correct values in these fields. Now how can there be an inconsistency? There are at least two possibilities: 1. Some fdisk programs seem to write incorrect values, especially end cylinders that are off by one or two. 2. You have an EIDE drive that uses address translation. Modern hard disks usually have more than 1024 cylinders, but DOS does not allow for cylinder numbers greater than 1024. This caused the hard disk controller manufacturers to implement a trick: they decrease the number of cylinders and increase the number of heads that DOS is told when asking for the drive geometry. So DOS thinks it has a drive with e.g. 63 sectors, 32 heads and 1000 cylinders, whereas the correct values are 63 sectors, 16 heads, 2000 cylinders. Now if DOS asks for the first sector on cylinder 500, it really gets the first sector on cylinder 1000. This trick is called address translation. Some newer EIDE drives allow the address translation to be switched on and off in the BIOS. In some cases this is changed after the disk is formatted. This means that the drive geometry that DOS gets when querying the disk controller differs from the geometry that the drive was formatted with and which is reflected in the partition table. This is no problem for DOS, but it was a problem for FIPS until release 1.4. In the current release, if FIPS detects this kind of problem, it will adapt the partition table to the changed disk geometry. The bottomline is that you need not worry about this message, it is perfectly normal. --------- Q08. FIPS displays an error message and refuses to work. What should I do? A08. ---- Although this is already addressed in FIPS.DOC, I can not emphasize it enough: If you send me email, please include the _DEBUG SCRIPT_ that you can produce with the -d switch. If you don't, I will have to ask you for it, and it will take longer to solve your problem. --------- Q09. FIPS does not recognize my SCSI disk. A09. ---- There exist older SCSI adapters (an Adaptec 1524 was reported to have that 'feature') that need a device driver that is loaded from the config.sys before the disk can be accessed (i.e. the system must be booted from a second hard disk or floppy). This device driver does not provide a 'BIOS level' interface but a 'DOS level' interface to the hard disk (for the technicians: it hooks into the DOS interrupt 21h instead of the BIOS inter- rupt 13h). This means that the partition table can only be accessed via a special fdisk program that knows about the adapters' internals. FIPS will not work on these drives (and in fact even DOS' fdisk won't either). Possibly there exists a newer driver for that adapter that will provide a BIOS level interface - ask the manufacturer. --------- Q10. FIPS only finds a partition with partition type 56h, no DOS partition. A10. ---- You have OnTrack Disk Manager installed. Read the relevant section in SPECIAL.DOC. --------- Q11. FIPS seems to work fine, and DOS sees the new partition, but Linux fdisk sees only one partition. A11. ---- Somehow DOS loads a different partition table than the one in the master boot record. There are two possible causes: 1. You use a device driver like OnTrack Disk Manager. See the file SPECIAL.DOC 2. You have a virus in the master boot record. This does not happen often, but it is quite possible. Some viruses install themselves in the MBR and copy the original MBR to some other place. When DOS tries to access the partition table, the virus intercepts the BIOS call and returns the backup copy, in order to hide from possible detection. Check this with a virus scanner after booting from a clean DOS boot disk. You can remove a virus from the MBR by using DOS fdisk with the /mbr option, but be aware that in this case the 'backup' partition table is not restored. Thus the boot sector will contain the new info as changed by FIPS, but the partition table will contain the original (single partition) setup. This inconsistency must be corrected (e.g. with a disk editor). --------- Q12. Does FIPS work with Windows 95? A12. ---- Yes. The file system of Windows 95 is the same as that of DOS. The only difference are the long file names, but FIPS works on a level below the directory level, so this is not a problem. Several people reported that FIPS worked flawlessly on a Win 95 partition.