[opensuse] Nested RAID 0+1 (SW)
Has anyone done a 0+1 SW RAID? I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller. I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1). Has anyone done such a setup using sw raid in openSUSE? -- Arun Khan -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Hi Arun, On Sun, 22 Mar 2009, 13:37:37 +0100, Arun Khan wrote:
Has anyone done a 0+1 SW RAID?
I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller.
I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1).
Has anyone done such a setup using sw raid in openSUSE?
Yes, I did, and it works great in general; I just configured the RAID0 on top of two RAID1 devices (because I _think_ it might be easier to deal with in case a disk goes havoc). As I'm a heavy multi-boot user, I tried to install a different version (e.g. openSUSE 11.1 32-bit vs 64-bit) and found out, that *none* of my md's or LV's on top of the md's were recognized :-( So, I deciced for me that this type of setup is probably too advanced at the moment; I now use the following configuration: /dev/sd{a,b,c,d}1 /mainboot (md-RAID1) # Chainloader /dev/sd{a,b,c,d}5 /boot-os1 # /boot for OS1 /dev/sd{a,b,c,d}6 /boot-os2 # /boot for OS2 /dev/sd{a,b,c,d}7 /boot-os3 # /boot for OS3 /dev/sd{a,b,c,d}8 /boot-os4 # /boot for OS4 /dev/sd{a,b,c,d}9 /boot-os5 # /boot for OS5 /dev/sd{a,b,c,d}10 /boot-os6 # /boot for OS6 /dev/sd{a,b,c,d}11 /boot-os7 # /boot for OS7 /dev/sd{a,b,c,d}12 /boot-os8 # /boot for OS8 /dev/sd{a,b,c,d}13 /boot-os9 # /boot for OS9 /dev/sd{a,b,c,d}14 /boot-os10 # /boot for OS10 /dev/sd{a,c}15 PV1 /dev/sd{b,d}15 PV2 I then keep all the OS related stuff plus _some_ space for ISOs etc in PV1, and use PV2 for e.g. /home shared by the various OSes. Works great, performance is very good due to the separation of OS and data specific traffic. HTH, cheers. l8er manfred -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Manfred Hollstein wrote:
Hi Arun,
On Sun, 22 Mar 2009, 13:37:37 +0100, Arun Khan wrote:
Has anyone done a 0+1 SW RAID?
I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller.
I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1).
Has anyone done such a setup using sw raid in openSUSE?
Yes, I did, and it works great in general; I just configured the RAID0 on top of two RAID1 devices (because I _think_ it might be easier to deal with in case a disk goes havoc). As I'm a heavy multi-boot user, I tried to install a different version (e.g. openSUSE 11.1 32-bit vs 64-bit) and found out, that *none* of my md's or LV's on top of the md's were recognized :-( So, I deciced for me that this type of setup is probably too advanced at the moment; I now use the following configuration:
Manfred, Please file a bug report on the installer failing to recognize raid setups. The installer is getting better, but obviously it still has holes in it. You can see where I left off with 11.1 and dmraid at: https://bugzilla.novell.com/show_bug.cgi?id=445602 -- David C. Rankin, J.D.,P.E. Rankin Law Firm, PLLC 510 Ochiltree Street Nacogdoches, Texas 75961 Telephone: (936) 715-9333 Facsimile: (936) 715-9339 www.rankinlawfirm.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Hi David, On Mon, 23 Mar 2009, 15:33:54 +0100, David C. Rankin wrote:
Manfred Hollstein wrote:
Hi Arun,
On Sun, 22 Mar 2009, 13:37:37 +0100, Arun Khan wrote:
Has anyone done a 0+1 SW RAID?
I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller.
I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1).
Has anyone done such a setup using sw raid in openSUSE?
Yes, I did, and it works great in general; I just configured the RAID0 on top of two RAID1 devices (because I _think_ it might be easier to deal with in case a disk goes havoc). As I'm a heavy multi-boot user, I tried to install a different version (e.g. openSUSE 11.1 32-bit vs 64-bit) and found out, that *none* of my md's or LV's on top of the md's were recognized :-( So, I deciced for me that this type of setup is probably too advanced at the moment; I now use the following configuration:
Manfred,
Please file a bug report on the installer failing to recognize raid setups. The installer is getting better, but obviously it still has holes in it. You can see where I left off with 11.1 and dmraid at:
Hmm, my situation may be different than yours as I don't use dmraid but plain vanilla soft md-raid{0,1}. FWIW, I just found out that using the raid10 mode instead of manually assembling a raid0 by combining two raid1's actually works and gets detected by the installer, so I'm OK now. Cheers. l8er manfred -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Hi Manfred, On Sunday 22 Mar 2009, Manfred Hollstein wrote:
On Sun, 22 Mar 2009, 13:37:37 +0100, Arun Khan wrote:
Has anyone done a 0+1 SW RAID?
I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller.
I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1).
Has anyone done such a setup using sw raid in openSUSE?
Yes, I did, and it works great in general; I just configured the RAID0 on top of two RAID1 devices (because I _think_ it might be easier to deal with in case a disk goes havoc). As I'm a heavy multi-boot user, I tried to install a different version (e.g.
.... snip ... Thanks much for sharing your experience on nested raid. I found the following discussion also very useful. http://en.wikipedia.org/wiki/Nested_RAID_levels There is no doubt, it needs to be planned out and then implemented. The main motivation for considering RAID0, I want to implement VMs with the virtual disks on RAID to take advantage of striping. I am wondering if is there any significant advantage of doing RAID 1+0 (4 disks) v/s RAID5 (3 disks). Thanks again. -- Arun Khan -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Hi Arun, On Tue, 24 Mar 2009, 06:00:35 +0100, Arun Khan wrote:
Hi Manfred,
On Sunday 22 Mar 2009, Manfred Hollstein wrote:
On Sun, 22 Mar 2009, 13:37:37 +0100, Arun Khan wrote:
Has anyone done a 0+1 SW RAID?
I am assembling an entry level server Intel s3000ah board, xeon 3220 2.4GHz, 8GB RAM and 4*160GB SATA II hdds. sda and sdb on one controller; sdc and sdd on an another controller.
I am thinking of configuring 2 disks (sda1+sdc1) in a RAID0 setup and then mirror this RAID device on the other 2 disks (sdb1+sdd1).
Has anyone done such a setup using sw raid in openSUSE?
Yes, I did, and it works great in general; I just configured the RAID0 on top of two RAID1 devices (because I _think_ it might be easier to deal with in case a disk goes havoc). As I'm a heavy multi-boot user, I tried to install a different version (e.g.
.... snip ...
Thanks much for sharing your experience on nested raid. I found the following discussion also very useful.
yep, I saw those pages, too.
There is no doubt, it needs to be planned out and then implemented.
Absolutely. I'm currently testing the raid10, which I never considered before. YaST's partitioner does not offer to create any RAID types other than 0, 1, and 5, so you have to do this from the command line, but that's how I always did it anyways ;-)
The main motivation for considering RAID0, I want to implement VMs with the virtual disks on RAID to take advantage of striping.
Indeed. As long as I only used two disks, mirroring was the only option, but with heavy load on the system, performance became really horrible sometimes due the disks seeking. Now I have 4 disks and also remembered the awesome performance with raid0... What I found out so far is, that while YaST cannot create such layouts itself, it is able to reuse existing raid10 devices, and this works in openSUSE 10.3, openSUSE 11.1, SLES 10, and SLES 11 (these are the ones I work with). At http://blog.jamponi.net/2007/12/some-raid10-performance-numbers.html there are some numbers indicating that we're on the right track ;-) FWIW, I'll most likely reconfigure my systems to use raid10.
I am wondering if is there any significant advantage of doing RAID 1+0 (4 disks) v/s RAID5 (3 disks).
I never actually used RAID5, but I read everywhere that write performance is quite bad (confirmed by the document above); but this is not surprising, as calculating the checksums for each block comes with a cost, of course.
Thanks again.
-- Arun Khan
HTH, cheers. l8er manfred -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
In <20090324080547.GA6422@saturn.hollstein.homelinux.org>, Manfred Hollstein wrote:
On Tue, 24 Mar 2009, 06:00:35 +0100, Arun Khan wrote:
I am wondering if is there any significant advantage of doing RAID 1+0 (4 disks) v/s RAID5 (3 disks).
RAID 1+0 on 4 disks is going to be faster than RAID 5 on 3 disks. Not a lot mind you, but it will be faster. There are also a few failure modes where 1+0 can recover from 2-disk failure where RAID 5 never does, so it does have a slight reliability advantage.
I never actually used RAID5,
I have used RAID 5 and RAID 6.
but I read everywhere that write performance is quite bad (confirmed by the document above);
Not in my experience.
but this is not surprising, as calculating the checksums for each block comes with a cost, of course.
The RAID 5 "checksum" is a simple XOR. It's is not even as complicated as CRC-16. I've never once seen it be the bottleneck in pushing data to a RAID 5 or 6 array, even when it is implemented in software. If it is implemented as software heavy disk I/O *will* cause CPU use, so it can make the system perform worse when both disk and CPU are under heavy load. RAID 5 on 3 disks is roughly as fast as RAID 0 across 2 disks. RAID 6 across 5 disks is roughly as fast as RAID 0 across 3 disks. You may be writing more data, but the disks can write in parallel, as long as you don't saturate your bus. -- Boyd Stephen Smith Jr. ,= ,-_-. =. bss@iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
participants (4)
-
Arun Khan -
Boyd Stephen Smith Jr. -
David C. Rankin -
Manfred Hollstein