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-   -   file systems, partitions, mounting drives. how to set up? (https://www.linuxquestions.org/questions/linux-newbie-8/file-systems-partitions-mounting-drives-how-to-set-up-756261/)

koyote 09-18-2009 03:50 PM

file systems, partitions, mounting drives. how to set up?
 
so i tried ubuntu and ran into some problems with their video drivers. next i ran open suse and everything ran fine but didnt like the interface it was weird. maybe it was kde. now im trying fedora.
for some reson fedora formated my drive differntly. i orginally had an ext3 and a swap. now i have a boot partition, an unnamed partition and an lvm partition and despite reading about not sure what the lvm is supposed to do. according to fedora website its a good a idea to make certain directories like boot, usr, etc. individual partitions. why is this? is there a standard format that linux follows or does it vary from one distro to another. also in suse i couldnt see certain drives that i was able to see with ubuntu. i dont know if this is something that suse did on purpose or if theyre not mounted. i am also confused where i should mount drives and how i should do it both command line and gui. ive read stuff about what certain directories are used for but it seems there are discrepancies between distros. can some one make sense out of all this.

MensaWater 09-18-2009 04:13 PM

1) Yes there are differences in the way different distros do things. It's a matter of preferences rather than absolutes. That is to say the people that maintain each distro decide to do things based on what they think makes most sense or their own philosophy of "simple" or "legal".

2) /boot is the boot area. The reason why distros such as RedHat/Fedora/CentOS put it on a partition rather than a logical volume (LV) is because that makes it accessible if for some reason Logical Volume Manager (LVM) isn't. LVM is an add on to a disk and/or partition.

3) Swap is a different area for allowing paging (virtual memory) operations. Swap can in LVM or on a partitition.

3) The benefits to LVM include:
a) Ability to combine multiple disks (or partitions) into one large unit called a Volume Group (VG). These are called Physical Volumes (PVs). A VG can be thought of as a logical disk.
b) Ability to subdivide the VG into multiple Logical Volumes (LVs). LVs can be thought of as logical partitions.
c) You can have far more LVs than you have physical partitions even if you only have one disk (or partition thereof) in your VG.
d) Your LVs can be adjusted more easily than your physical partitions as they can use extents before and after another LV. With physical partitions if you wanted grow partition 2 but already had a partition 3 you'd have to delete partition 3 then grow partition 2 then recreate partition 3. Whereas if you had lvol2 and lvol3 you could simply grow lvol2 to use the space after lvol3.

By default RedHat/Fedora/CentOS will setup a boot partition and another partition which is used as the PV for VG named VolGroup00. It will then allocate a single filesystem called "/" (root) on an LV using all the space. However during the install you are asked if you want to change it. Typically we break it up here into multiple LVs for /, /usr, /opt, /tmp, /var and leave most of the space unallocated until we have need for it.

koyote 09-18-2009 06:33 PM

i kind of get the LVM but isnt that like RAID? some of the directories (like dev, mnt, etc) are repeated inside other places in the directory. are these real or just like virtual directories based on the user (kind of how windows registry creates a main folder for the user). which /mnt is the drive actually mounted to and for that matter what is difference between hda and hda1. which do i mount and where? theres like 30 differnt things in there i only have 1 drive w/ 2 part. and 1 dvd

MensaWater 09-21-2009 08:59 AM

To a certain extent LVM is like (software) RAID in that it can be used to concatenate multiple disks into a single VG. However with a real mdadm software RAID you can set other RAID levels (mirroring, RAID5 etc...). You also have the same limitations of the RAID LUN without LVM that it has a small number (compartively) of partitions available and you'd have to rearrange things just as you do with a physical disk's partitions if you wanted to expand one that already had another one beyond it.

Ideally you'd have BOTH LVM and RAID (other than RAID 0) if you have multiple disks. The LVM gives you the flexibility I mentioned in earlier post where RAID gives you disk protection so that losing a single disk doesn't lose all your data.

chrism01 09-21-2009 06:38 PM

Here's a good explanation howto of LVM http://tldp.org/HOWTO/LVM-HOWTO/
By comparison, see raid http://en.wikipedia.org/wiki/RAID
Hopefully, these will clarify things.


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