Q: Online resizing ext3 FS
Hi I apologize in advance for asking a question not really appropriate for this mailing list, but I couldn't find a better place with lots of people managing lots of disk space. The question: Has anyone of you been using ext2online to resize (large) ext3 filesystems? I have to do it going from 500GB to 1TB on a productive system I was wondering if you have some horror/success stories. I'm using RHEL4/U4 (kernel 2.6.9) on this system. Thanks for your time. Regards, Chris UNIX System Engineer Swisscom Mobile Ltd. Switzerland - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: accessing mirrired lvm on shared storage
On Wed, 12 Apr 2006 14:09:52 +1000 Neil Brown [EMAIL PROTECTED] wrote: On Friday April 7, [EMAIL PROTECTED] wrote: Unfortunately md lacks the ability to mark an array as used/busy/you_name_it. Sometime ago I asked on this list for such an enhancement (see thread with subject Question: array locking, possible). Although I managed (with great help from few people on this list) to attract Neil's attention, I couldn't fine enough arguments to convince him to put this topic on hist TO-DO list. Neil, you see the constantly growing number of potential users of this feature? ;-) I don't think that just marking an array don't mount is really a useful solution. And if it was, it would be something done in 'mdadm' rather than in 'md'. I don't think I understand this bit, sorry, but see below. What you really want is cluster wide locking using DLM or similar. That way when the node which has active use of the array fails, another node can pick up automatically. But I also want to prevent accidentally activation of the array on the stand-by node. That would mean make mdadm cluster or a lock manager aware, which we certainly don't want. That's why I'm asking for a flag on the array which would be far less complex solution than a Lock Manager. Then we could put a flag in the superblock which says 'shared', and md would need a special request to assemble such an array. That would mean, if I get you right, Attention, it could be used on another host, go and check or let me assemble it anyway if you know what you're doing. I was thinking about a flag saying locked which would mean array is assembled/used. Look, if I have a cluster (active/stand-by) when starting it I assemble my array in exclusive mode by setting the locked flag. If I do a manual fail-over of my package/service using the array in question, when stopping the array the flag gets cleared. The node which takes over finds the array unlocked, locks, assembles and uses it. Now the active node crashes without clearing the flag. It is now responsibility of the cluster software to force the assembly of the array on the node taking over. And nobody can accidentally/unwittingly assemble the array on stand-by node (without giving the option -I_know_what_I_am_doing ;-), which currently is my main concern as I haven't experienced any crashes or malfunction of my clusters yet. Touching wood It is how ServiceGuard cluster software on HP-UX works except that disk mirroring and locking is done in LVM. Moreover LVM does know about SG Cluster and prevents you from doing certain operations depending on the current state of the cluster. One thing that is on my todo list is supporting shared raid1, so that several nodes in the cluster can assemble the same raid1 and access it - providing that the clients all do proper mutual exclusion as e.g. OCFS does. Your desire to have only-assembled-once would be trivial to include in that. If this is what I described above, I hold my breath ;-) NeilBrown Thanks very much for your time. Regards, Chris - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: accessing mirrired lvm on shared storage
Matthias I have currently four clusters which mirror shared storage. I've always pay great attention not to have an array active on both cluster nodes. I can imagine data corruption would happen soon or late. Unfortunately md lacks the ability to mark an array as used/busy/you_name_it. Sometime ago I asked on this list for such an enhancement (see thread with subject Question: array locking, possible). Although I managed (with great help from few people on this list) to attract Neil's attention, I couldn't fine enough arguments to convince him to put this topic on hist TO-DO list. Neil, you see the constantly growing number of potential users of this feature? ;-) Regards, Chris PS Matthias, just curious, you don't have FC failover, right? On Thu, 06 Apr 2006 20:19:53 +0200 Matthias Eble [EMAIL PROTECTED] wrote: Hi all, I've got an extended setup whith two Systems, each with two FC cards. Every card is connected to a seperate disk array (so one system accesses two arrays). The other node has access to the same two arrays (standby). The active server mirrors the data (4 LUNs) between the two arrays via md. On top is a LVM physical volume. The other system is meant to be booted but not acessing the VGs. My question is, if it is possible to let both systems set up the md mirror without corrupting the data? Is there any data written even when the VGs are not taken active? I think I remember that LVM refuses to activate volumegroups which are active on another system, right? This would save me from caring about IO fencing. thanks for your help in advance.. matthias - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
Rick On HP-UX disk mirroring is done in LVM. I'm using md driver for mirroring and LVM on top of it. Controlling access to my disks in LVM is just too late. I would have to assemble the array before I can activate VGs. If the array in question is being used on the other host nobody can guarantee that bad thing wont happen. And what I would like to prevent is: two hosts accessing (writing) an array. Thanks anyway for the hint. Regards, Chris On Thu, 9 Feb 2006 10:28:58 -0800 Stern, Rick (Serviceguard Linux) [EMAIL PROTECTED] wrote: There is more interest, just not vocal. May want to look at LVM2 and its ability to use tagging to control enablement of VGs. This way it is not HW dependent. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Osicki Sent: Thursday, February 09, 2006 2:26 AM To: linux-raid@vger.kernel.org Subject: Re: Question: array locking, possible? It looks like we are the only two md users interested in such a feature. Not enough to get Neil's attention ;-) Regards, Chris On Wed, 8 Feb 2006 21:45:33 +0100 Jure Peèar [EMAIL PROTECTED] wrote: On Wed, 8 Feb 2006 11:55:49 +0100 Chris Osicki [EMAIL PROTECTED] wrote: I was thinking about it, I have no idea how to do it on Linux if ever possible. I connect over fibre channel SAN, using QLogic QLA2312 HBAS, if it matters. Anyone any hints? I too am running a jbod with md raid between two machines. So far md never caused any kind of problems, altough I did have situations where both machines were syncing mirrors at once. If there's a little tool to reserve a disk via scsi, I'd like to know about it too. Even a piece of code would be enough. -- Jure Peèar http://jure.pecar.org/ - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
Luca On Thu, 9 Feb 2006 21:48:48 +0100 Luca Berra [EMAIL PROTECTED] wrote: On Thu, Feb 09, 2006 at 10:28:58AM -0800, Stern, Rick (Serviceguard Linux) wrote: There is more interest, just not vocal. May want to look at LVM2 and its ability to use tagging to control enablement of VGs. This way it is not HW dependent. I believe there is space in md1 superblock for a cluster/exclusive flag, if not the name field could be used Great if there is space for it there is a hope. Unfortunately I don't think my programming skills are up to such a task as making proof-of-concept patches. what is missing is an interface between mdadm and cmcld so mdadm can ask cmcld permission to activate an array with the cluster/exclusive flag set. For the time being we could live without it. I'm convinced HP would make use of it once it's there. And I wouldn't say mdadm should get permission from cmcld (for those who don't know Service Guard cluster software from HP: cmcld is the Cluster daemon). IMHO cmcld should clear the flag on the array when initiating a fail-over in case the host which used it crashed. Once again, what I would like it for is for preventing two hosts writing the array at the same time because I accidentally activated it. Without cmcld's awareness of the cluster/exclusive flag I would always run mdadm with the '--force' option to enable the array during package startup, because if I trust the cluster software I know the fail-over is happening because the other node crashed or it is a manual (clean) fail-over. We can discuss details of SG integration after Neil implemented this flag. I can hope, you already found space for it ... ;-) Regards, Chris L. -- Luca Berra -- [EMAIL PROTECTED] Communication Media Services S.r.l. /\ \ / ASCII RIBBON CAMPAIGN XAGAINST HTML MAIL / \ - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
Rick You must have missed my first posting, or maybe I was not clear enough. We _are_ talking about the same thing. Now we are already three or four thinking of it as a useful feature, the pression on Neil is dramatically increasing ... ;-) Regards, Chris On Mon, 13 Feb 2006 09:21:06 -0800 Stern, Rick (Serviceguard Linux) [EMAIL PROTECTED] wrote: I understand about HP-UX mirroring/LVM. I was a little too obtuse. LVM2 has a feature (not well advertised) that allows an VG to be tagged so it will not be activated by system b if it is already tagged as being in use by system a. I was suggesting that a similar feature could be added to MD. This way a MD array could be marked as owned and, if so, mdadm would not activate it from another system. This way all of the MD control is still within mdadm. If Neil is interested, I'll try to dig up more info. Regards, Rick -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Osicki Sent: Monday, February 13, 2006 9:13 AM To: linux-raid@vger.kernel.org Subject: Re: Question: array locking, possible? Rick On HP-UX disk mirroring is done in LVM. I'm using md driver for mirroring and LVM on top of it. Controlling access to my disks in LVM is just too late. I would have to assemble the array before I can activate VGs. If the array in question is being used on the other host nobody can guarantee that bad thing wont happen. And what I would like to prevent is: two hosts accessing (writing) an array. Thanks anyway for the hint. Regards, Chris On Thu, 9 Feb 2006 10:28:58 -0800 Stern, Rick (Serviceguard Linux) [EMAIL PROTECTED] wrote: There is more interest, just not vocal. May want to look at LVM2 and its ability to use tagging to control enablement of VGs. This way it is not HW dependent. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Osicki Sent: Thursday, February 09, 2006 2:26 AM To: linux-raid@vger.kernel.org Subject: Re: Question: array locking, possible? It looks like we are the only two md users interested in such a feature. Not enough to get Neil's attention ;-) Regards, Chris On Wed, 8 Feb 2006 21:45:33 +0100 Jure Peèar [EMAIL PROTECTED] wrote: On Wed, 8 Feb 2006 11:55:49 +0100 Chris Osicki [EMAIL PROTECTED] wrote: I was thinking about it, I have no idea how to do it on Linux if ever possible. I connect over fibre channel SAN, using QLogic QLA2312 HBAS, if it matters. Anyone any hints? I too am running a jbod with md raid between two machines. So far md never caused any kind of problems, altough I did have situations where both machines were syncing mirrors at once. If there's a little tool to reserve a disk via scsi, I'd like to know about it too. Even a piece of code would be enough. -- Jure Peèar http://jure.pecar.org/ - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
It looks like we are the only two md users interested in such a feature. Not enough to get Neil's attention ;-) Regards, Chris On Wed, 8 Feb 2006 21:45:33 +0100 Jure Peèar [EMAIL PROTECTED] wrote: On Wed, 8 Feb 2006 11:55:49 +0100 Chris Osicki [EMAIL PROTECTED] wrote: I was thinking about it, I have no idea how to do it on Linux if ever possible. I connect over fibre channel SAN, using QLogic QLA2312 HBAS, if it matters. Anyone any hints? I too am running a jbod with md raid between two machines. So far md never caused any kind of problems, altough I did have situations where both machines were syncing mirrors at once. If there's a little tool to reserve a disk via scsi, I'd like to know about it too. Even a piece of code would be enough. -- Jure Peèar http://jure.pecar.org/ - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
On Tue, 07 Feb 2006 10:16:20 -0800 Mike Hardy [EMAIL PROTECTED] wrote: Chris Osicki wrote: To rephrase my question, is there any way to make it visible to the other host that the array is up an running on the this host? Any comments, ideas? Would that not imply an unlock command before you could run the array on the other host? Yes, it would. I was thinking about an advisory lock, and a well known -f option for those who know what they are doing ;-) Would that not then break the automatic fail-over you want, as no machine that died or hung would issue the unlock command, meaning that the fail-over node could not then use the disks If I trust my cluster software it's not a problem, I use the -f. My concern is as I said accidentally array activation on the other node. It's an interesting idea, I just can't think of a way to make it work unattended It might be possible wrap the 'mdadm' binary with a script that checks (maybe via some deep check using ssh to execute remote commands, or just a ping) the hosts status and just prints a little table of host status that can only be avoided by passing a special --yes-i-know flag to the wrapper It has been done, more or less what you are thinking about. The cluster I'm currently working on is Service Guard on Linux. The original platform is HP-UX. They use LVM for mirroring and device locking is on LVM level. The active cluster node activates a volume group in exclusive mode. This writes a kind of flag onto the disk. Should the node die without a chance to clear the flag, the node taking over the service knows what happened and forces the take-over of the volume group. This feature is missing on Linux. I already have a Linux cluster which has been running for over one year w/o problems. I've just setup three more and to sleep better I'm looking for a way to diminish chances of a disaster due to a operation fault. Regards, Chris -Mike - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Question: array locking, possible?
I was thinking about it, I have no idea how to do it on Linux if ever possible. I connect over fibre channel SAN, using QLogic QLA2312 HBAS, if it matters. Anyone any hints? Thanks and regards, Chris On Tue, 07 Feb 2006 14:26:13 -0500 Paul Clements [EMAIL PROTECTED] wrote: Chris Osicki wrote: The problem now is how to prevent somebody on the other host from accidentally assembling the array. Because the result of doing so would be something from strange to catastrophic ;-) To rephrase my question, is there any way to make it visible to the other host that the array is up an running on the this host? I don't know how the storage boxes are attached to the servers, but you might be able to use SCSI reservations, if the storage supports them. -- Paul - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Question: array locking, possible?
Hi Is there any way to lock an active array? To make clear what I'm after: I have two machines forming a fail-over cluster connected over SAN to two storage boxes which provide them with a disk each. I created a RAID1 using those two disks. Both cluster nodes see both disks but only one node, the active one uses them by assembling the array. During a fail-over I stop the array on the active node and assemble it on the node becoming active. It works OK, or at least I haven't seen any problems for quite a long time now. The problem now is how to prevent somebody on the other host from accidentally assembling the array. Because the result of doing so would be something from strange to catastrophic ;-) To rephrase my question, is there any way to make it visible to the other host that the array is up an running on the this host? Any comments, ideas? Thanks for your time. Regards, Chris - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Question: read-only array
Hi I've just noticed that setting an array readonly doesn't really make it readonly. I have a RAID1 array and LVM on top of it. When I run /sbin/mdadm --misc --readonly /dev/md0 /proc/mdstat shows: Personalities : [raid1] md0 : active (read-only) raid1 sda[0] sdb[1] 160436096 blocks [2/2] [UU] However, it doesn't prevent me from activating volume groups, mounting filesystems and write files onto it. Is it a bug, feature or my misunderstanding of the meaning of readonly flag? I use RedHat AS 4 (U1) on a dual core Opteron machine. Kernel 2.6.9-11.ELsmp as delivered with RH. mdadm - v1.12.0 - 14 June 2005 Thanks for your time. Regards, Chris - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Q: Moving raid1 array to another host, safe?
Hi I have two Linux boxes running kernel 2.4.21 having access to two devices over fibre channel SAN. What I'm trying to achive is host based mirroring with ability to move the storage from one host to another. On the firs host I created a raid1 array, put LVM on it, created a filesystem. To move the storage to the second host I do the following (on the first host): deactivate volume group: vgchange -an dxvg stop array: mdadm --misc --stop /dev/md0 Then on the second host: assemble the array: mdadm --assemble /dev/md0 /dev/emcpowera /dev/emcpowerb activate the volume group: vgchange -ay dxvg The following procedure seams to be working OK. However, I'm asking myself how safe is it what I'm doing? Thanks for your time. Regards, Chris - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
