Re: [Xen-API] XCP + RAID

[Scott Zupek <scottz@xxxxxxxxx>]

On 12/22/11 7:33 AM, George Shuklin wrote:

You will not gain any performance boost with fake raid - it offload all operations on host, this is exactly same as normal software raid. The single reason fakeraid exists is 'faking' raid existence for windows, may version of it does not support mirroring (all desktops windows, f.e.). It have no meaning for linux. \

Your point was understood the first time, no fake raid. Got it.

Anyway, I can say one thing: don't do this. Any lowlevel manipulation with 'fakeraid' and XCP will make you getting a nasty problems you will need to fix by yourself (without community help).

If you playing with XCP - turn 'raid' to 'hba' (sata ahci) in bios and use a single drive.

At this point I am trying to install Debian on a software raid but I can't get the darn thing to bootup. Raid has been turned off and all 4 SATA3 drives are set to ACHI mode.  Grub is a nightmare and apparently "mdm raid" software is the way to go. I have been trying to get this to work for a few days now.

If you wants to use this in product - think about proper hardware. nForce is NOT A SERVER solution.

I completely understand the nForce is NOT a server solution, but in all reality, this is 1 server hosting 3 or maybe 4 servers for my I.T. consulting company. I don't need top of the line performance so I don't need the 1000+ USD raid cards. nForce has yet to fail me and I am not runnign a data center, so those speed differences are negotiable. nForce is still a hardware solution, but moreso geared towards high end users/workstations.  Regardless I gave up on the hardware raid as that system board didn't support AM3+.  I understand that I am between a home user and a business class/enterprise user.  That's why I am trying to get Xen Hypervisor and XCP to work correctly. :)

PS XCP supports up to 32 cores, so 8 core shall works fine.

That is actually great to know.  Thank you.  It sounds like I'll have to get XCP to work with Xen Hypervisor running on top  Debian (with DOM0 kernel).  Since it's not as easy as the XCP ISO/Hypervisor, hopefully I can get it to a manageable state using XenCenter.  speaking of, is there a "better"/more unified management tool beyond XenCenter? I don't want management to be complicated, I am just curious.

Thank you for the help/responses.  This is all new techology(software wise) to me and I love learning as I go. I apologize if I am filling the mailing list with off topic material.  Since it all goes back to XCP-API I thought it might pertain.

Scott

On 22.12.2011 01:30, Scott Zupek wrote:

Sorry for the reply and not changing the topic, that was sucky of me.  My apologies please.

So if software raid, wont hinder performance and since I already have these 4 drives to run Raid, could I boot into Debian Live and run the software raid and install Xen Hypervisor on that?  True I don't get the added benefits of the DOM0 w/ XCP, but it's still (once fully configured) a stand alone server that I don't have to worry much about.

Unforunately, I thought it was read Raid like the nForce controller, but apparently AMD got me on this one. I just bought the Motherboard and CPU (8 core, but it looks like the DOM0 only detects 5 threads, so maybe I am better off with the 6 core one I have).

So to run Xen Hypervisor + XCP(??) to manage, would I still get the same results as running the ISO hypervisor version? (maybe not AS fast)?

Thank you for your time. Should I be using a different thread / mailing list for this question?

Scott




On 12/21/11 3:17 PM, George Shuklin wrote:

On 22.12.2011 00:45, Scott Zupek wrote:

I am re-installing XCP 1.1 via ISO and it looks like it can't find the raid controller driver because it's listing all the drives individually.

Since I am not very familiar with the Linux side of Raid, do I need to download the Linux driver (if there is even one available) and put it on a floppy like Windows?

Motherboard = ASUS M5A97EVO
RAID Controller AMD SB950 chipset

Raid type = 1+0 *aka raid 10

First, please, never reply to maillist with new topic, you causing wrong thread ordering of messages. If you wish to start new topic, just write it to maillist address.

Second, there is two issues:

1) Don't use fake raid under linux. Linux has perfect software raid, which much more reliable and much less troublemaking, compare to fake raid (you device is fake raid, because it don't actually do anything with drives).
2) Sad to say, but XCP have very serious issues with raid support. We using software raid with XCP in our company, but we created very specifically crafted ISO image with lots ad-hoc fixes and hacks. I can't recommend do this to anyone, who don't really deep enough in XCP to do this by himself.

So, you have to opportunities:
a) use real hardware raid (to get raid array as  /dev/sda).
b) Do not use raid in anyway (configure fake raid to HBA mode) - use external storage and don't bother for XCP system drive. If host die, no data will be lost.



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