Software Raid 5
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Software Raid 5
by Brown, Larry
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OK, I'm going to ask a stupid question. I'm sure I must have run across
this in the past but can't find any mention of it now... Is it possible to allow a small group of nodes to boot to an init node where the init node is still running off initrd, mount their disks with software raid, and pivot root over to them allowing the root filesystem to be fault tolerant with software raid 5? Larry Brown _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Ed King
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If you want the root to be fault tolerant, a standard debian
installation allows this (Sarge 3.1). We partition each drive with a small boot partition (~50MB) , some swap space (1GB) and the rest being allocated for RAID. The installer is told that the first drive, first partition is mounted as boot, the other primary partitions on the other drives are not designated to be mounted (the debian installer can't have more than one drive mounted to the boot point). The installer allows the creation of the raid, and we flag that as mounting as the root filesystem -- it gives us a very large software raid, and on the faster processors can actually give better performance than hardware raids. The boot partition never changes (unless we upgrade the kernel) and is small enough so we use dd to copy it over to the other unused partitions so all the drives are now bootable. Brown, Larry wrote: > OK, I'm going to ask a stupid question. I'm sure I must have run across > this in the past but can't find any mention of it now... > > Is it possible to allow a small group of nodes to boot to an init node > where the init node is still running off initrd, mount their disks with > software raid, and pivot root over to them allowing the root filesystem > to be fault tolerant with software raid 5? > > Larry Brown > > > > > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > > _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by David Bo Jensen
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What is AOE devices?
If Raid 5 is possible as you describe it, then DRBD will not make much sense, would it? ----- Original Message ----- From: "Brown, Larry" <Larry.Brown@...> To: "Ed King" <edk@...> Cc: <ssic-linux-users@...> Sent: Monday, June 19, 2006 7:40 PM Subject: [Norton AntiSpam] Re: [SSI-users] Software Raid 5 > My apologies, I should have been more specific. I have also come across > a number of posts touching on software raid. I was referring to > inter-node software raid IE: > > md0 > /dev/1/hda2 > /dev/2/hda2 > /dev/3/hda2 > /dev/4/hda2 > > Where loss of node 1 would not constitute loss of the cluster. If this > is not possible with the md code that is in the kernel due to the > underlying architectural changes, is it possible to do this with AOE > devices? > > > Larry Brown > > -----Original Message----- > From: Ed King [mailto:edk@...] > Sent: Monday, June 19, 2006 1:27 PM > To: Brown, Larry > Cc: ssic-linux-users@... > Subject: Re: [SSI-users] Software Raid 5 > > If you want the root to be fault tolerant, a standard debian > installation allows this (Sarge 3.1). > > We partition each drive with a small boot partition (~50MB) , some swap > space (1GB) and the rest being allocated for RAID. > > The installer is told that the first drive, first partition is mounted > as boot, the other primary partitions on the other drives are not > designated to be mounted (the debian installer can't have more than one > drive mounted to the boot point). > > The installer allows the creation of the raid, and we flag that as > mounting as the root filesystem -- it gives us a very large software > raid, and on the faster processors can actually give better performance > than hardware raids. The boot partition never changes (unless we > upgrade the kernel) and is small enough so we use dd to copy it over to > the other unused partitions so all the drives are now bootable. > > Brown, Larry wrote: >> OK, I'm going to ask a stupid question. I'm sure I must have run >> across this in the past but can't find any mention of it now... >> >> Is it possible to allow a small group of nodes to boot to an init node > >> where the init node is still running off initrd, mount their disks >> with software raid, and pivot root over to them allowing the root >> filesystem to be fault tolerant with software raid 5? >> >> Larry Brown >> >> >> >> >> _______________________________________________ >> Ssic-linux-users mailing list >> Ssic-linux-users@... >> https://lists.sourceforge.net/lists/listinfo/ssic-linux-users >> >> > > > > > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > > _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Alexander (Sasha) Wait
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On 6/19/06, Brown, Larry <Larry.Brown@...> wrote:
> AOE stands for ATA over Ethernet. There is a kernel driver that sets up > a drive as /dev/etherd/eX.Y where X is a shelf the actual drive is > designated to be on and Y is the drive within that shelf you are > addressing. The communication for reads/writes is done over Ethernet > and so you can have raid over the network where two drives are on > different racks / power supplies etc. > RAID5 is pretty slow--even with hardware assist--I can't imagine it would be any fun over ethernet. But what about software mirroring over ethernet? iSCSI is a pretty standard way to get Xen clusters booted diskless. And I suppose you could probably do software mirroring this way. People on the list have probably done it (with or without OpenSSI.) Anyone? Sasha -- http://freelogy.org/wiki/User:AlexanderWait (GnuPG ID 4153C516) _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Roger Tsang
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DRBD-SSI is good for HA storage consolidation and when it works
reduces SPOF versus dedicated NAS. Try to look at mountpoints in OpenSSI like a virtual service in that the cluster as a whole can survive by transparent failover to any node (any initnode for rootfs) that are connected to the same storage. Roger On 6/19/06, Brown, Larry <Larry.Brown@...> wrote: > I don't know if DRBD was a way to simplify the task or if there are > other reasons it was chosen. I didn't make the choice to use DRBD so I > can't answer as to why it makes any more sense than any other mechanism. > AOE stands for ATA over Ethernet. There is a kernel driver that sets up > a drive as /dev/etherd/eX.Y where X is a shelf the actual drive is > designated to be on and Y is the drive within that shelf you are > addressing. The communication for reads/writes is done over Ethernet > and so you can have raid over the network where two drives are on > different racks / power supplies etc. > > I'm assuming that if you can have root failover with directly connected, > shared, drives that the AOE method should work as well, but was hoping > someone would have experience with this. > > I just don't grasp how the cluster handles the loss of the system that > made the initial mount when it goes away. For instance, if there was a > complete array stored in an initrd and that initrd was booted and 3 > primary units joined the array, could you pivot root over to a software > raid consisting of 3 drives one on each box. Then if it is possible, > could you then turn off the system from which the cluster was booted and > the cluster continue to run? > > > Larry Brown > > -----Original Message----- > From: ssic-linux-users-bounces@... > [mailto:ssic-linux-users-bounces@...] On Behalf Of > David Bo Jensen > Sent: Monday, June 19, 2006 2:45 PM > To: ssic-linux-users@... > Subject: Re: [SSI-users] Software Raid 5 > > What is AOE devices? > If Raid 5 is possible as you describe it, then DRBD will not make much > sense, would it? > > > ----- Original Message ----- > From: "Brown, Larry" <Larry.Brown@...> > To: "Ed King" <edk@...> > Cc: <ssic-linux-users@...> > Sent: Monday, June 19, 2006 7:40 PM > Subject: [Norton AntiSpam] Re: [SSI-users] Software Raid 5 > > > > My apologies, I should have been more specific. I have also come > across > > a number of posts touching on software raid. I was referring to > > inter-node software raid IE: > > > > md0 > > /dev/1/hda2 > > /dev/2/hda2 > > /dev/3/hda2 > > /dev/4/hda2 > > > > Where loss of node 1 would not constitute loss of the cluster. If > this > > is not possible with the md code that is in the kernel due to the > > underlying architectural changes, is it possible to do this with AOE > > devices? > > > > > > Larry Brown > > > > -----Original Message----- > > From: Ed King [mailto:edk@...] > > Sent: Monday, June 19, 2006 1:27 PM > > To: Brown, Larry > > Cc: ssic-linux-users@... > > Subject: Re: [SSI-users] Software Raid 5 > > > > If you want the root to be fault tolerant, a standard debian > > installation allows this (Sarge 3.1). > > > > We partition each drive with a small boot partition (~50MB) , some > swap > > space (1GB) and the rest being allocated for RAID. > > > > The installer is told that the first drive, first partition is mounted > > as boot, the other primary partitions on the other drives are not > > designated to be mounted (the debian installer can't have more than > one > > drive mounted to the boot point). > > > > The installer allows the creation of the raid, and we flag that as > > mounting as the root filesystem -- it gives us a very large software > > raid, and on the faster processors can actually give better > performance > > than hardware raids. The boot partition never changes (unless we > > upgrade the kernel) and is small enough so we use dd to copy it over > to > > the other unused partitions so all the drives are now bootable. > > > > Brown, Larry wrote: > >> OK, I'm going to ask a stupid question. I'm sure I must have run > >> across this in the past but can't find any mention of it now... > >> > >> Is it possible to allow a small group of nodes to boot to an init > node > > > >> where the init node is still running off initrd, mount their disks > >> with software raid, and pivot root over to them allowing the root > >> filesystem to be fault tolerant with software raid 5? > >> > >> Larry Brown > >> > >> > >> > >> > >> _______________________________________________ > >> Ssic-linux-users mailing list > >> Ssic-linux-users@... > >> https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > >> > >> > > > > > > > > > > _______________________________________________ > > Ssic-linux-users mailing list > > Ssic-linux-users@... > > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > > > > > > > > > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > > > > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Roger Tsang
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OpenSSI CFS is similar to
http://h30097.www3.hp.com/cluster/cfs_wp_1002.pdf if this helps you understand what goes on. Roger On 6/22/06, Brown, Larry <Larry.Brown@...> wrote: > How does OpenSSI handle the fail over on shared hardware? Is the > redundant master mounting read only until the current master fails and > then re-mounts? Does each mount rw and OpenSSI prevents the fail over > machine from writing until the failure of the current master? > > > Larry Brown > > -----Original Message----- > From: ssic-linux-users-bounces@... > [mailto:ssic-linux-users-bounces@...] On Behalf Of > Alexander (Sasha) Wait > Sent: Monday, June 19, 2006 4:25 PM > To: ssic-linux-users@... > Subject: Re: [SSI-users] Software Raid 5 > > On 6/19/06, Brown, Larry <Larry.Brown@...> wrote: > > AOE stands for ATA over Ethernet. There is a kernel driver that sets > > up a drive as /dev/etherd/eX.Y where X is a shelf the actual drive is > > designated to be on and Y is the drive within that shelf you are > > addressing. The communication for reads/writes is done over Ethernet > > and so you can have raid over the network where two drives are on > > different racks / power supplies etc. > > > RAID5 is pretty slow--even with hardware assist--I can't imagine it > would be any fun over ethernet. But what about software mirroring over > ethernet? iSCSI is a pretty standard way to get Xen clusters booted > diskless. And I suppose you could probably do software mirroring this > way. > > People on the list have probably done it (with or without OpenSSI.) > > Anyone? > > Sasha > > > > -- > http://freelogy.org/wiki/User:AlexanderWait (GnuPG ID 4153C516) > > > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > > > All the advantages of Linux Managed Hosting--Without the Cost and Risk! > Fully trained technicians. The highest number of Red Hat certifications in > the hosting industry. Fanatical Support. Click to learn more > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 > _______________________________________________ > Ssic-linux-users mailing list > Ssic-linux-users@... > https://lists.sourceforge.net/lists/listinfo/ssic-linux-users > Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Chris de Vidal
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--- Roger Tsang <roger.tsang@...> wrote:
> OpenSSI CFS is similar to > http://h30097.www3.hp.com/cluster/cfs_wp_1002.pdf if this helps you > understand what goes on. I looked at that PDF, but does OpenSSI's CFS do hardware redundancy? That is, if the root node fails does the whole cluster die? It appears only to offer a single unified filesystem but not failover capability. >From what I can tell, that's why OpenSSI integrated DRBD into the root node (something I could never get to work). CD Are you good enough? TenThousandDollarOffer.com Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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Re: Software Raid 5
by Ivan Krstić-3
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Chris de Vidal wrote:
> I looked at that PDF, but does OpenSSI's CFS do hardware redundancy? Yes. > That is, if the root node fails does the whole cluster die? Not if you have a failover initnode set up. This depends on having shared storage between the initnodes, either in hardware (NAS) or in software (DRBD). -- Ivan Krstic <krstic@...> | GPG: 0x147C722D Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Ssic-linux-users mailing list Ssic-linux-users@... https://lists.sourceforge.net/lists/listinfo/ssic-linux-users |
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