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ianw1974

Aug 27 2008, 08:12 PM

Finished putting the machine together today, and here is what we have so far:

Intel® Core™2 Quad CPU Q6600 @ 2.40GHz
8GB RAM (4GB swap)
4 x 250GB Seagates with 32MB cache attached to Adaptec 1430 SA Raid Controller

Not using the raid because Adaptec only have kernel modules for Red Hat/SUSE, so I'm just using it as a disk controller with no raid.

Partition setup on system:

CODE

Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000adb0c

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1         499     4008186   82  Linux swap / Solaris
/dev/sda2   *         500        2990    20008957+  83  Linux
/dev/sda3            2991       30401   220178857+  83  Linux

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000aef4a

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       30401   244196001   8e  Linux LVM

Disk /dev/sdc: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000b02be

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1       30401   244196001   8e  Linux LVM

Disk /dev/sdd: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000ac775

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1               1       30401   244196001   8e  Linux LVM

/dev/sda being my main system, and the three other disks are assigned as an LVM. Created a volumegroup called vg:

CODE

esprit / # vgs
VG #PV #LV #SN Attr VSize VFree
vg 3 0 0 wz--n- 698.65G 698.65G

and you can see just short of 700GB for that one volumegroup. I can then create logical volumes within this for various mountpoints as and when I need to. But because of the LVM, it's also a good setup for Xen Virtualisation - when I got the system compiled how I want it (Gentoo 2008.0).

Sweet

Lexicon

Aug 27 2008, 08:34 PM

OK, and where place is for Mandriva in Your live? ....Lex

theYinYeti

Aug 28 2008, 06:16 AM

You mention LVM. I was tempted and used it for the server at work.
Then I wasn't able to find any tool that works for managing the LVM, thus defeating the whole idea.
I thought I would be able to add space, resize space, remove space from the LVM, and do this on the live system. I found I was only able to add and resize, and the latter only after the partition was unmounted and in a very awkward way…

What do you use for managing the LVM in an efficient and secure manner?

For example, resizing (for me) was done by first shrinking the filesystem, and then shrinking the LVM. I don't find it secure at all: both tools speak different units, and I have no clue what each filesystem "overhead" is around its data, and I had no way to check that the second resize wasn't one byte too short or too far compared to the first.

Yves.

ianw1974

Aug 28 2008, 06:33 AM

I'm just using the console for managing the LVM partitions at present. The group I shouldn't need to resize, since all the partitions will be inside the group, so for creating the partitions I use lvcreate, and so on for the other tools also. I've yet to do it all, but it seems quite straightforward to use LVM.

theYinYeti

Aug 28 2008, 01:02 PM

Thank you for your answer Ian. Well… maybe I'm just trying to do too much too soon

I'll have to learn and master the beast gradually.

Yves.

ianw1974

Aug 28 2008, 01:30 PM

I'll let you know how I get on when my machine is finally working. Gentoo is gone now, Ubuntu 8.04 is installed but Xen won't work on it. Trying to get Fedora 9 downloaded so that I can see how Xen will work on this. I wanted CentOS 5 but tbe built-in ethernet on the motherboard doesn't work, and I don't want to be compiling kernels to get everything working correctly

scarecrow

Aug 28 2008, 02:25 PM

4GB of swap is a total waste of space, but it's also true that HD space is quite cheap currently...

arctic

Aug 28 2008, 02:49 PM

QUOTE (scarecrow @ Aug 28 2008, 04:25 PM)

4GB of swap is a total waste of space, but it's also true that HD space is quite cheap currently...

AFAIK, if you have 2 GB RAM and want to have a working hibernate mode, you need the 4GB RAM. Or am I wrong?...

ianw1974

Aug 28 2008, 08:15 PM

I've got 8GB of RAM, so probably don't need the swap, but gave it 4GB just in case

I could have done the double-the-ram theory and left 16GB of swap, but that really would have been a waste

But yeah, if suspend is going to be used, double-the-ram would still apply for suspend to ram to work.

scarecrow

Aug 28 2008, 09:05 PM

QUOTE (arctic @ Aug 28 2008, 05:49 PM)

AFAIK, if you have 2 GB RAM and want to have a working hibernate mode, you need the 4GB RAM. Or am I wrong?...

You are right, but this is applicable for a laptop system, not a desktop one.
Other than that, even a laptop user can suspend-to-ram and avoid having a huge swap file... but there are also other suspend-to-disk options which do not store the data to the swap partition.
Personally, I am using (on my laptop) a swap partition equal to my RAM, to be able to suspend-to-disk using the usual kernel commands... but I may reconsider, as I rarely use that feature.
On a desktop system with 8G, either no swap at all (or even recompiling your kernel to exclude swap usage), or using a minimal (say 256M) swap, seems more to the point.

ianw1974

Aug 29 2008, 06:32 AM

I generally played it safe because I'm going to use Xen on the system, so if I have a lot of machines on at the same time, I might need the swap. I dunno yet, until I play with it a bit more and see what happens. I may even reduce it later anyway depending on how it all works out. That's the good thing with Linux, I can move all my partitions about without having to reinstall (providing it's done correctly).

ianw1974

Aug 29 2008, 12:38 PM

Sadly, over the past few days I've not been able to find a distro where Xen is working other than CentOS 5.

Gentoo 2008.0 was problematic in getting things to work correctly.
Ubuntu 8.04 just doesn't work with Xen, even though there are installable packages - there is a bug on this already that has gone unfixed since the release.
Fedora 9 is a disappointment on Fedora 8 with lots of things just behaving strangely. Incidently, the Fedora 9 xen kernel will not boot my system at all.
Mandriva 2008.1 Spring also doesn't have a working Xen installation, and it's xen kernel also won't boot my system.

After finding another network card (3COM) and installing this instead of using the onboard Altansic Gigabyte card, CentOS 5 is working fine along with Xen.

Why other distributions have a problem with this I've no idea. Anyway, I'm completely happy with CentOS 5 just disappointed at all the others. They're better off not having the packages available than having something that is obviously completely broken.

scarecrow

Aug 29 2008, 01:41 PM

FYI Archlinux has (in the AUR repo) a kernel specially built for xen usage, and AFAIK it does work fine (or so its users say- myself is quite OK with the cheapo VirtualBox virtualization solution).

viking777

Aug 29 2008, 06:28 PM

Ref the discussion on Hiberante and Ram. My laptop has 2Gb of ram and 1Gb of swap space and it hibernates perfectly.

Just thought you might like to know.

ianw1974

Aug 30 2008, 09:12 AM

Yes, this would be OK providing that you're not using the full 2GB of ram. If all 2GB was being used when you suspended, then you might have a problem suspending to 1GB. Unless of course, it's suspending to disk and not to ram. Hibernate usually goes to disk rather than to ram because hibernate usually becomes active when the battery is about to run out completely. Therefore, meaning you don't lose it if it was in memory like suspend to ram would be.

viking777

Aug 30 2008, 11:04 AM

QUOTE (ianw1974 @ Aug 30 2008, 11:12 AM)

I see, thanks for that explanation, it makes sense that if you are using all the ram at the time you want to suspend then it is not going to work very well.

iphitus

Sep 2 2008, 05:41 AM

I've used ram>swap before for s2disk too without any problems. For most laptop use cases it works fine, you'll probably be finishing up doing something, so there won't be much running, and cache's are all flushed before suspend freeing up plenty too.

The whole swap = 2xRam rule of thumb is totally obsolete.

ian: For the raid, a lot of Linux kernel developers advocate using software raid instead. Many of the cheap "hardware raid" cards out there aren't actually full hardware raid cards - they depend heavily on software too - aka "fakeraid". Unfortunately, yours is on the fakeraid list, hence the need for the closed source drivers -- that's where a lot of the work is really being done.
http://linuxmafia.com/faq/Hardware/sata.html

Why software RAID:
http://linux.yyz.us/why-software-raid.html

ianw1974

Sep 2 2008, 06:17 AM

Yep, I knew about the software raid thing in a chip on the cards, for me though this card is much faster than if I use the on-board sata ports, which is why I'm using, just not as a raid controller anymore - due to problems with trying to get the controller to work if I had raid setup through it.

Proper raid controllers for hardware raid are far more expensive, but this option at least helps me improve my disk performance.

Incidently, I love the software raid in Linux because when I upgraded my machine, I had 2 x 160GB IDE which had been using software raid 1 in Linux. I was able to connect them to the new system, re-assemble the array and get my data. That would have been impossible or almost impossible with a software raid controller. That's my sales pitch for the Linux software raid

Thanks for the links, they give some really cool info on what to choose

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