Difference between revisions of "Some basics of MBR v/s GPT and BIOS v/s UEFI"
Some basics of MBR v/s GPT and BIOS v/s UEFI (view source)
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From: https://en.wikipedia.org/wiki/BIOS | From: https://en.wikipedia.org/wiki/BIOS | ||
== UEFI == | == UEFI == | ||
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The original EFI (Extensible Firmware Interface) specification was developed by Intel. Some of its practices and data formats mirror ones from Windows.] In 2005, UEFI deprecated EFI 1.10 (final release of EFI). The UEFI specification is managed by the Unified EFI Forum. | The original EFI (Extensible Firmware Interface) specification was developed by Intel. Some of its practices and data formats mirror ones from Windows.] In 2005, UEFI deprecated EFI 1.10 (final release of EFI). The UEFI specification is managed by the Unified EFI Forum. | ||
== BIOS vs. UEFI == | |||
UEFI enables better use of bigger hard drives. Though UEFI supports the traditional master boot record (MBR) method of hard drive partitioning, it doesn't stop there. It's also capable of working with the GUID Partition Table (GPT), which is free of the limitations the MBR places on the number and size of partitions. GPT ups the maximum partition size from 2.19TB to 9.4 zettabytes. | |||
UEFI may be faster than the BIOS. Various tweaks and optimizations in the UEFI may help your system boot more quickly it could before. For example: With UEFI you may not have to endure messages asking you to set up hardware functions (such as a RAID controller) unless your immediate input is required; and UEFI can choose to initialize only certain components. The degree to which a boot is sped up will depend on your system configuration and hardware, so you may see a significant or a minor speed increase. | |||
Technical changes abound in UEFI. UEFI has room for more useful and usable features than could ever be crammed into the BIOS. Among these are cryptography, network authentication, support for extensions stored on non-volatile media, an integrated boot manager, and even a shell environment for running other EFI applications such as diagnostic utilities or flash updates. In addition, both the architecture and the drivers are CPU-independent, which opens the door to a wider variety of processors (including those using the ARM architecture, for example). | |||
From: http://www.pcmag.com/article2/0,2817,2392944,00.asp | |||
== MBR vs. GPT and BIOS vs. UEFI == | |||
Usually, MBR and BIOS (MBR + BIOS), and GPT and UEFI (GPT + UEFI) go hand in hand. This is compulsory for some systems (eg Windows), while optional for others (eg Linux). | |||
http://en.wikipedia.org/wiki/GUID_Partition_Table#Operating_systems_support | |||
http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#DISKDEVCOMPAT | |||
=== Converting from MBR to GPT === | |||
From http://www.rodsbooks.com/gdisk/mbr2gpt.html | |||
One of the more unusual features of gdisk is its ability to read an MBR partition table or BSD disklabel and convert it to GPT format without damaging the contents of the partitions on the disk. This feature exists to enable upgrading to GPT in case the limitations of MBRs or BSD disklabels become too onerous—for instance, if you want to add more OSes to a multi-boot configuration, but the OSes you want to add require too many primary partitions to fit on an MBR disk. | |||
Conversions from MBR to GPT works because of inefficiencies in the MBR partitioning scheme. On an MBR disk, the bulk of the first cylinder of the disk goes unused—only the first sector (which holds the MBR itself) is used. Depending on the disk's CHS geometry, this first cylinder is likely to be sufficient space to store the GPT header and partition table. Likewise, space is likely to go unused at the end of the disk because the cylinder (as seen by the BIOS and whatever tool originally partitioned the disk) will be incomplete, so the last few sectors will go unused. This leaves space for the backup GPT header and partition table. (Disks partitioned with 1 MiB alignment sometimes leave no gaps at the end of the disk, which can prevent conversion to GPT format—at least, unless you delete or resize the final partition.) | |||
The task of converting MBR to GPT therefore becomes one of extracting the MBR data and stuffing the data into the appropriate GPT locations. Partition start and end points are straightforward to manage, with one important caveat: GPT fdisk ignores the CHS values and uses the LBA values exclusively. This means that the conversion will fail on disks that were partitioned with very old software. If the disk is over 8 GiB in size, though, GPT fdisk should find the data it needs. | |||
Once the conversion is complete, there will be a series of gaps between partitions. Gaps at the start and end of the partition set will be related to the inefficiencies mentioned earlier that permit the conversion to work. Additional gaps before each partition that used to be a logical partition exist because of inefficiencies in the way logical partitions are allocated. These gaps are likely to be quite small (a few kilobytes), so you're unlikely to be able to put useful partitions in those spaces. You could resize your partitions with GNU Parted to remove the gaps, but the risks of such an operation outweigh the very small benefits of recovering a few kilobytes of disk space. | |||
=== Switching from BIOS to UEFI === | |||
See: [[UEFI_-_Install_Guide#Switching_from_BIOS_to_UEFI]] | |||
=== Note === | |||
'''Switching from [MBR + BIOS] to [GPT + UEFI]''' | |||
Switching from BIOS to UEFI consists of 2 parts- | |||
i. Conversion of disk from MBR to GPT. | |||
Side effects- Possible Data Loss, other OS installed on same disk may or may not boot (eg Windows).. | |||
ii. Changing from BIOS to UEFI (and installing GRUB in UEFI mode). | |||
Side Effects- Other OS (can be both Linux and Windows) may or may not boot, with systemd you need to comment out the swap partition in /etc/fstab on a GPT partition table (if you use a swap partition). | |||
After converting from MBR to GPT, probably your installed Manjaro wont work, so you would need to prepare beforehand what to do in such a case. | |||
(eg, chroot using a live disk and installing GRUB in UEFI way) | |||
And Windows 8 if installed in MBR way, would need to be repaired/reinstalled in accordance to UEFI way. | |||
== Feedback == | |||
Questions, suggestions, critics? Please post here: [http://forum.manjaro.org/index.php?topic=11427.0] | |||
== See Also == | |||
* '''[[UEFI_-_Install_Guide]]''' | |||
[[Category:Contents Page]] | |||