Advice needed on partitions, LVM

Azazwa · 07-12-2010, 03:57 AM

Hi!

I have a computer with 2 x 1TB harddisks.
There is a 100 GB partition for Windows 7 on sda1.
We want to use the computer for chemical computations, by running the chemical software on SuSE (SLES 10).

I followed another person's advice on setting up the computer, but it seems that a lot of his advice was outdated and now I have a very rigid and unwieldy system.

At present the calculation results are stored in the specific user's home directory on sdb1, but I have some space available on sda that I would like to use for the results as well.

Look at this:

Code:

b104pc110 /root# fdisk -l

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      102400    7  HPFS/NTFS
Partition 1 does not end on cylinder boundary.
/dev/sda2              14       13144   105474757+   7  HPFS/NTFS
/dev/sda3           13145       26199   104864287+  83  Linux
/dev/sda4           26200      121601   766316565    f  W95 Ext'd (LBA)
/dev/sda5           26200       27505    10490413+  82  Linux swap / Solaris
/dev/sda6           27506       32727    41945683+  83  Linux
/dev/sda7           32728       39255    52436128+  83  Linux
/dev/sda8           39256       65362   209704446   83  Linux

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      121601   976760001    f  W95 Ext'd (LBA)
/dev/sdb5               1      121601   976759969+  83  Linux

What I would like is that the space on /sda3 and the extra space on the extended partition be used as "overflow" for sdb1. (Or that sdb1 be used as an overflow when a new partition on sda becomes full from the calculation results.)
I was thinking of removing sda3, moving the extended partition to the "left" and having about an extra 400GB at the end of sda.

I have been reading a little about LVM, but I'm still unsure.

Would LVM be the best option to follow for this, or could one somehow use a "link" or something like that? (I guess an added benefit of LVM would be that I could then easily add another harddisk when the need arises, not so?)

If LVM is the way to go, then do I have to re-install Linux (and Windows) or would it only affect what is on sdb1 and the extra space on sda?

Your advice and suggestions will be greatly appreciated!

;-)

alli_yas · 07-12-2010, 05:09 AM

Hi

If I understand you correctly, you want to first start storing your calcuations on sda3; and thereafter onto sdb5 if required?

LVM would definitely be useful if this is what you want to achieve. Basically you would create multiple Physical Volumes; including sda3 and whatever sdbX partitions you may have.

Thereafter you allocate these to a volume group and a logical volume; and then LVM will automatically manage your storage for you.

You would most probably have to re-install in this scenario; but the Linux install won't destroy your Windows partition.

My final comment is around your calculation results - how big are they - do you really require more than the 400GB on sda? The reason I ask is since I think you'd be better off creating a mirror; where everything written to sda is written to sdb (RAID 1) - this would allow for your data protection to be much better.

Azazwa · 07-12-2010, 05:42 AM

Hi!

Thanks!

Quote:

If I understand you correctly, you want to first start storing your calcuations on sda3; and thereafter onto sdb5 if required?

Yeah, that's more or less what I mean. I was thinking of removing sda3,(the other guy had a reason for putting it there) and "moving the space to the right" but if I have to do a re-install, then it doesn't matter, as I'll just format the Linux partitions and re-do everything. Fortunately, it is a new installation.

The calculations are rather big (though, depending on how big your molecule is), and we would like to use this computer for some time to come.

Hm, I haven't thought of the mirror idea. sda8 is supposed to be seperate so that special (or final) results can be stored there, but I think the other guy intended the chemistry users to manually move their results there.

See, I will probably not be around this computer for much longer. I want to do the job well and set it up so that people who are even more clueless than myself don't have to go digging for answers, and then hand it over to its real owner and let him play with it.

Okay, so you suggest that I just do a re-installation and set the LVM and other partitions during installation?

alli_yas · 07-12-2010, 06:44 AM

Yes go for it - what I'd suggest you though beforehand, is maybe post what your plan of action is - what would your paritioning table look like, and so forth - since its a pain to have to redo everything again if you make a mistake.

Azazwa · 07-12-2010, 08:35 AM

I guess I would format the Linux partitions with GParted.
Then I would put in the Linux installation disks.

Here is what I think the partition table would roughly look like:
sda1 & sda2 for Windows as is.
sda3 extended partition for swap, /, /code and /final (approximate size as shown earlier)
sda4 for the extra space to be combined with sdb into a volume group using LVM (to be done somehow during the installation looking at http://tldp.org/HOWTO/LVM-HOWTO and http://www.novell.com/documentation/...l/ch01s08.html)

Should I use the typical PE size of 4MB or make it larger, say 8MB?

Any additional suggestions?

alli_yas · 07-12-2010, 08:55 AM

Quote:

sda3 extended partition for swap, /, /code and /final (approximate size as shown earlier)

I would recommend separating / and swap into separate partitions (can be LV's as well) and maybe add in a separate partition for boot (300MB max should be fine).

PE size of 4MB should be fine - I've used this and transferred large volumes of data with no problems.

Those guides (links) you have in your last post are great - if you get stuck along the way post here and I'll try my best to help.

arashi256 · 07-12-2010, 09:42 AM

The PE size determines the maximum size of the Logical Volume. With the default 4 MB extent size, this imposes a Logical Volume size limitation of 256GB. You only need to increase the Physical Extend size from the default if you anticipate a Logical Volume size greater than 256GB.

A 32MB extent size would give you 2TB maximum size Logical Volume. I guess you could increase it still further but I don't think x86-based systems can handle more than that anyway.