RAID 10 help.

R

Rotting

Hi guys,

I have 4 really fast big drives that I'd like to use RAID 10 with, but....I ONLY have these 4 drives. Is it possible to use RAID 10 for everything (/ /tmp /var /usr , etc.)

I was thinking of doing it this way. Install FreeBSD (7.2) onto one of the disks. Creating mirror0 and mirror1 out of two pairs. Then creating stripe out of mirror0 and mirror1.

Well, I was able to create the mirrors. mirror0 has the OS on it now. mirror1 has nothing. What do I do from here? I'm assuming that I can't stripe two mirrors when one of the mirrors has the entire OS on it.

Thanks for your help.
 
I'd stipe 2 drives first, then install, then mirror the stripe set.
 
I'd stipe 2 drives first, then install, then mirror the stripe set.
Click to expand...

Why? just curious. That'd be a raid01 right? This would not be striping across two mirrors. Then what, create a mirror in degraded mode out of the two stripes and let it rebuild? That would take more time. Is that how to create a mirror without loosing data? I've heard of creating an array in degraded mode and let it rebuild but I've never tried it. What's the reason to do it this way?

I was thinking of doing it this way. Install FreeBSD (7.2) onto one of the disks.
Click to expand...

Just one of the four discs? why? Then the data won't be striped across two mirrors. Each mirror should have half the data, you know, every other "chunk".

Creating mirror0 and mirror1 out of two pairs. Then creating stripe out of mirror0 and mirror1.
Click to expand...

So I assume one of the mirrors has the one disc you already installed onto? So you will have a complete copy of the data on each of the four drives? You lost me there. How do you get your data to the other drives after installing onto one? And only half the data should be on each mirror not all of it. What's the point of doing it that way? Why not make the raid10 first then install onto it. Isn't that your end goal to have a raid10 with FreeBSD on it? The install will be faster going onto a raid 10 instead of a single drive. The resultant raid10 will look like one big drive to the system and you can slice it up like one for everything (/ /tmp /var /usr , etc.). Someone correct me if I'm wrong.
 
SeaHag said:
That'd be a raid01 right?



Just one of the four discs? why?



Does this include the one disc you already installed onto? You lost me there. What's the point of doing it that way and can you do it in steps like that without loosing the data? Why not make the raid10 first then install onto it. Isn't that your end goal to have a raid10 with FreeBSD on it? The install will be faster going onto a raid 10 instead of a single drive.
Click to expand...

I didn't know that I could build the RAID during installation. Otherwise, I definitely would have. Would you mind pointing me in the right direction?
 
I'm sorry I don't know how to do it during install or if it's even possible. Now wouldn't that be a nice FreeBSD feature. Just pick the drives you want and configure and install. I was thinking of hardware raid. You'll have to google for FreeBSD raid. I also heard BSD can't boot from raid0, I don't know if this also includes raid10 since it's a stripe too. Oops, looks like vinum doesn't do raid10, maybe CCD, GEOM? Maybe the way you were saying is good. How do you do it though? Migrate the first drive to a mirror, then migrate that data to a raid10? That might work but seems like a challenge. I've never done it but I've heard of creating a degraded mirror then let it rebuild. That would get your data to the other drive but then how to convert that to a raid10 since only half the data needs to be on each mirror. If there's a way to migrate the data from a mirror to a raid 10 your home free. What were you going to use to do it?

http://www.vinumvm.org/
http://onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html
 
This how-to shows how to take an installed FreeBSD system on a single disk, and turn it into a RAID1 setup using gmirror(8). Works quite nicely, and is what we use to create our bootable RAID1 setups.

You can expand on that by using gstripe(8) to create the RAID0 parts, in a similar fashion.

(I can never remember which order the RAID levels go, whether it's a stripeset of two mirrors, or a mirror of two stripesets. I believe you want to do the RAID0 part as the top layer, though.)
 
Hardware RAID10 doesn't boot

Hi,
I'd really appreciate it if somebody could help me out!
I have a box with a MB ASUS P5WDG2-WS Pro with two built-in SATA II RAID controllers (Intel ICH7R and Marvell 88SE6141).
I installed 4 HDD WD WD5002ABYS (500GB each) on the 4 SATA ports of the Intel ICH7R and using the Intel Matrix Storage Manager I created a RAID10 (Strip 14KB, Size 931.5GB, Status Normal, Bootable Yes) out of these 4 HDD.

Then in the BIOS I set the IDE Configuration to Configure SATA As [RAID], OnBoard Serial-ATA BOOTROM [Enabled] and disabled the Marvell SATA RAID controller, for I use only the Intel ICH7R.

Then I successfully installed FreeBSD 7.1 on the RAID partition, ar0.

The installation completed successfully but the system persistently didn't boot and gave this error message:

Code: 
F1    FreeBSD Default: F1 No /boot/loader FreeBSD/i386 boot Default: 0:ad(0,a)/boot/kernel/kernel boot: No /boot/kernel/kernel

Why? What is wrong?

Thanks a lot,
Alex
 
I'm guessing ...
Code: 
boot -s /ar0/boot/kernel # or similar
Some command at that prompt shows all possible /devices?
the geom_ar.ko or similar is loaded/loadable there/already?
(Sorry, even guessing as to the "-s")
 
Looks like the boot record was not installed correctly.
If you only have one system to boot on this computer, you dont need a bootmanager.
You can just install a standard mbr

http://www.freebsd.org/doc/en/books/handbook/install-steps.html

---

Second thing:

Please read http://www.FreeBSD.org/cgi/man.cgi?...ion=0&manpath=FreeBSD+8.0-RELEASE&format=html carefully. Your "hardware raid" is more a software raid. FreeBSD cant rebuild it or even tell the Intel Matrix Storage Manager that a disk causing problems and is degraded. So you may run into serious problems you dont want.
 
Well, perhaps my initial question should have been as follows: Can FreeBSD 7.1 booot from a RAID10 partition?
I tried all the suggested booting options, but alas, to no avail!
 
A stripeset of two mirrors is RAID10, which is more fault-tolerant.
A mirror of two stripesets is RAID01, which is less fault-tolerant.
Hence, for servers RAID10 is better than RAID01. Am I right?
 
freebsd can certianly boot from hardware raid10 as I use that setup on 2 different high end servers, freebsd see's it as a raid5 device but nevertherless it works.

software I have no idea, I suggest if you want to use raid10 spend some money on a hardware controller, it will likely cost far less than the 4 drives cost.
 
THe Intel ICH7R controller is a fake RAID, and I didn't know that. I thought it was a hardware RAID.
FreeBSD cannot boot from software or fake RAID stripes.
Now, only for root I use a 2GB USB flash stick and it works like a charm. Many thanks for all those who wanted to help!
 
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