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?
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
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?
On Mon, Feb 13, 2006 at 06:52:47PM +0100, Chris Osicki wrote:
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.
i was thinking of adding a bit in the feature_map flags to enable this
kind of behaviour, the downside of it is that kernel space code has to
be updated to account for this flags, as it is for anything in the
superblock except for name.
Neil, what would you think of reserving some more space in the superblock for
other data which can be used from user-space?
i believe playing with name is a kludge.
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.
i was thinking something like a socket based interface between mdadm and
a generic cluster daemon, non necessarily cmcld.
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.
no, i don't like the flag to be cleared, there is too much space for a
race. The flag should be permanent (unless it is forcibly removed with
mdadm --grow).
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.
if you only want this, it could be entirely implemented into mdadm, just
adding a exclusive flag to the ARRAY line in mdadm.conf
this is not foolproof, as it will only prevent mdadm -As from assembling
a device, providing the identification information on the command line
or running something like mdadm -Asc partitions, to fool it.
--
Luca Berra -- [EMAIL PROTECTED]
Communication Media Services S.r.l.
/\
\ / ASCII RIBBON CAMPAIGN
XAGAINST HTML MAIL
/ \
diff -urN mdadm-2.3.1/Assemble.c mdadm-2.3.1.exclusive/Assemble.c
--- mdadm-2.3.1/Assemble.c 2006-01-25 08:01:10.0 +0100
+++ mdadm-2.3.1.exclusive/Assemble.c2006-02-13 22:48:04.0 +0100
@@ -34,7 +34,7 @@
mddev_dev_t devlist,
int readonly, int runstop,
char *update,
-int verbose, int force)
+int verbose, int force, int exclusive)
{
/*
* The task of Assemble is to find a collection of
@@ -255,6 +255,15 @@
continue;
}
+ if (ident-exclusive != UnSet
+ !exclusive ) {
+ if ((inargv verbose = 0) || verbose 0)
+ fprintf(stderr, Name : %s can be activated in
exclusive mode only.\n,
+ devname);
+ continue;
+ }
+
+
/* If we are this far, then we are commited to this device.
* If the super_block doesn't exist, or doesn't match others,
* then we cannot continue
diff -urN mdadm-2.3.1/ReadMe.c mdadm-2.3.1.exclusive/ReadMe.c
--- mdadm-2.3.1/ReadMe.c2006-02-06 05:09:35.0 +0100
+++ mdadm-2.3.1.exclusive/ReadMe.c 2006-02-13 22:27:26.0 +0100
@@ -147,6 +147,7 @@
{scan, 0, 0, 's'},
{force,0, 0, 'f'},
{update, 1, 0, 'U'},
+{exclusive, 0, 0, 'x'},
/* Management */
{add, 0, 0, 'a'},
diff -urN mdadm-2.3.1/config.c mdadm-2.3.1.exclusive/config.c
--- mdadm-2.3.1/config.c2005-12-09 06:00:47.0 +0100
+++ mdadm-2.3.1.exclusive/config.c 2006-02-13 22:23:02.0 +0100
@@ -286,6 +286,7 @@
mis.st = NULL;
mis.bitmap_fd = -1;
mis.name[0] = 0;
+ mis.exclusive = 0;
for (w=dl_next(line); w!=line; w=dl_next(w)) {
if (w[0] == '/') {
@@ -386,6 +387,8 @@
fprintf(stderr, Name : auto type of
\%s\ ignored for %s\n,
w+5,
mis.devname?mis.devname:unlabeled-array);
}
+ } else if (strncasecmp(w,
Re: Question: array locking, possible?
On Mon, Feb 13, 2006 at 10:53:43PM +0100, Luca Berra wrote: diff -urN mdadm-2.3.1/Assemble.c mdadm-2.3.1.exclusive/Assemble.c please note that the patch was written while i was composing the email as a proof-of-concept, it should not be considered working (or even compiling code) 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
Re: Question: array locking, possible?
Jure Pečar wrote: 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. The sg3_utils can do this, if your hardware is compatible. -- 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
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?
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
Re: Question: array locking, possible?
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 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. 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
Re: Question: array locking, possible?
On Thursday February 9, [EMAIL PROTECTED] wrote: It looks like we are the only two md users interested in such a feature. Not enough to get Neil's attention ;-) :-) Just because I haven't said anything doesn't mean I'm not listening. Cluster awareness is definitely on my radar. I have no firm plans yet but I'm certainly interested in understanding the issues. So I'm listening.. NeilBrown - 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
Re: Question: array locking, possible?
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 Pečar 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
Re: Question: array locking, possible?
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? 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 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 -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
Re: Question: array locking, possible?
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
