Re: [PATCH] enable auto=yes by default when using udev
I think I'm leaning towards auto-creating names if they look like standard names (or are listed in mdadm.conf?), but required auto=whatever to create anything else. The auto= option has the disadvantage that it is different for partitionable and regular arrays -- is there no way to detect from the array if it is supposed to be partitionable or not? As it is scripts are better off creating the node with correct major/minor and assembling without auto=. Regards, C. - 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: [PATCH] enable auto=yes by default when using udev
Michael Tokarev wrote: Neil Brown wrote: On Monday July 3, [EMAIL PROTECTED] wrote: Hello, the following patch aims at solving an issue that is confusing a lot of users. when using udev, device files are created only when devices are registered with the kernel, and md devices are registered only when started. mdadm needs the device file _before_ starting the array. so when using udev you must add --auto=yes to the mdadm commandline or to the ARRAY line in mdadm.conf following patch makes auto=yes the default when using udev The principle I'm reasonably happy with, though you can now make this the default with a line like CREATE auto=yes in mdadm.conf. However + + /* if we are using udev and auto is not set, mdadm will almost +* certainly fail, so we force it here. +*/ + if (autof == 0 access(/dev/.udevdb,F_OK) == 0) + autof=2; + I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. Why to test for udev at all? If the device does not exist, regardless if udev is running or not, it might be a good idea to try to create it. Because IT IS NEEDED, period. Whenever the operation fails or not, and whenever we fail if it fails or not - it's another question, and I think that w/o explicit auto=yes, we may ignore create error and try to continue, and with auto=yes, we fail on create error. I have to agree here, I can't think of a case where creation of the device name would not be desirable, udev or no. But to be cautious, perhaps the default should be to create the device if the path starts with /dev/ or /tmp/ unless auto creation is explicitly off. I don't think udev or mount points come into the default decision at all, there are just too many options on naming. Note that /dev might be managed by some other tool as well, like mudev from busybox, or just a tiny shell /sbin/hotplug script. Note also that the whole root filesystem might be on tmpfs (like in initramfs), so /dev will not be a mountpoint. Agree with both points. Also, I think mdadm should stop creating strange temporary nodes somewhere as it does now. If /dev/whatever exist, use it. If not, create it (unless, perhaps, auto=no is specified) directly with proper mknod(/dev/mdX), but don't try to use some temporary names in /dev or elsewhere. True, but I don't see a case where this would be useful. And if it is, then add an auto=obscure_names option for the case where you really want that behaviour. In case of nfs-mounted read-only root filesystem, if someone will ever need to assemble raid arrays in that case.. well, he can either prepare proper /dev on the nfs server, or use tmpfs-based /dev, or just specify /tmp/mdXX instead of /dev/mdXX - whatever suits their needs better. Because /dev and /tmp are well known special cases, I would default auto for them. In other cases explicit behavior could be specified. Feel free to point out something bad which occurs by using this default behavior. -- bill davidsen [EMAIL PROTECTED] CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - 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: [PATCH] enable auto=yes by default when using udev
On Tuesday July 4, [EMAIL PROTECTED] wrote: Michael Tokarev [EMAIL PROTECTED] wrote: Why to test for udev at all? If the device does not exist, regardless if udev is running or not, it might be a good idea to try to create it. Because IT IS NEEDED, period. Whenever the operation fails or not, and Perhaps it was just a typo and you damage more if you just create it. Typical behaviour is to *not* just create device nodes because they don't exist but instead assume administrators know what they do. That's why I personally think it's better to rely on administrator's decision about automatic creation of device nodes. Yes, the typo issue is a real one. But so is the frustration with devices not appearing where you would expect. I think I'm leaning towards auto-creating names if they look like standard names (or are listed in mdadm.conf?), but required auto=whatever to create anything else. 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: [PATCH] enable auto=yes by default when using udev
Neil Brown wrote: On Monday July 3, [EMAIL PROTECTED] wrote: Hello, the following patch aims at solving an issue that is confusing a lot of users. when using udev, device files are created only when devices are registered with the kernel, and md devices are registered only when started. mdadm needs the device file _before_ starting the array. so when using udev you must add --auto=yes to the mdadm commandline or to the ARRAY line in mdadm.conf following patch makes auto=yes the default when using udev The principle I'm reasonably happy with, though you can now make this the default with a line like CREATE auto=yes in mdadm.conf. However + +/* if we are using udev and auto is not set, mdadm will almost + * certainly fail, so we force it here. + */ +if (autof == 0 access(/dev/.udevdb,F_OK) == 0) +autof=2; + I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. Why to test for udev at all? If the device does not exist, regardless if udev is running or not, it might be a good idea to try to create it. Because IT IS NEEDED, period. Whenever the operation fails or not, and whenever we fail if it fails or not - it's another question, and I think that w/o explicit auto=yes, we may ignore create error and try to continue, and with auto=yes, we fail on create error. Note that /dev might be managed by some other tool as well, like mudev from busybox, or just a tiny shell /sbin/hotplug script. Note also that the whole root filesystem might be on tmpfs (like in initramfs), so /dev will not be a mountpoint. Also, I think mdadm should stop creating strange temporary nodes somewhere as it does now. If /dev/whatever exist, use it. If not, create it (unless, perhaps, auto=no is specified) directly with proper mknod(/dev/mdX), but don't try to use some temporary names in /dev or elsewhere. In case of nfs-mounted read-only root filesystem, if someone will ever need to assemble raid arrays in that case.. well, he can either prepare proper /dev on the nfs server, or use tmpfs-based /dev, or just specify /tmp/mdXX instead of /dev/mdXX - whatever suits their needs better. /mjt - 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: [PATCH] enable auto=yes by default when using udev
On Tue, Jul 04, 2006 at 12:46:03AM +0200, Luca Berra wrote: On Mon, Jul 03, 2006 at 09:14:38AM +1000, Neil Brown wrote: However + + /* if we are using udev and auto is not set, mdadm will almost +* certainly fail, so we force it here. +*/ + if (autof == 0 access(/dev/.udevdb,F_OK) == 0) + autof=2; + I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. is /dev/.udev/db a debianism? no it is not in this case a check for both might suffice, else i will have to think harder about it. -- 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: [PATCH] enable auto=yes by default when using udev
Michael Tokarev [EMAIL PROTECTED] wrote: Why to test for udev at all? If the device does not exist, regardless if udev is running or not, it might be a good idea to try to create it. Because IT IS NEEDED, period. Whenever the operation fails or not, and Perhaps it was just a typo and you damage more if you just create it. Typical behaviour is to *not* just create device nodes because they don't exist but instead assume administrators know what they do. That's why I personally think it's better to rely on administrator's decision about automatic creation of device nodes. regards Mario -- As a rule, the more bizarre a thing is, the less mysterious it proves to be. -- Sherlock Holmes by Arthur Conan Doyle - 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: [PATCH] enable auto=yes by default when using udev
Jason Lunz [EMAIL PROTECTED] wrote: there's a udevd you can check for. I don't know whether that's a better test or not. It's not. For example, the Debian package does also start this udevd on package upgrades, even when a 2.4 kernel is running which definitely has no udev support :) regards Mario -- Programmieren in C++ haelt die grauen Zellen am Leben. Es schaerft alle fuenf Sinne: den Schwachsinn, den Bloedsinn, den Wahnsinn, den Unsinn und den Stumpfsinn. [Holger Veit in doc] - 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: [PATCH] enable auto=yes by default when using udev
Neil Brown wrote: I guess I could test for both, but then udev might change again I'd really like a more robust check. Maybe I could test if /dev was a mount point? IIRC you can have diskless machines with a shared root and nfs mounted static /dev/ David -- - 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: [PATCH] enable auto=yes by default when using udev
On Mon, Jul 03, 2006 at 09:14:38AM +1000, Neil Brown wrote: I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. Maybe I could test if /dev was a mount point? Any other ideas? Maybe checking for a running 'udevd' process? Frank -- Frank Blendinger | fb(at)intoxicatedmind.net | GPG: 0x0BF2FE7A Fingerprint: BB64 F2B8 DFD8 BF90 0F2E 892B 72CF 7A41 0BF2 FE7A Just because I don't care doesn't mean I don't undestand. (Homer Simpson) signature.asc Description: Digital signature
Re: [PATCH] enable auto=yes by default when using udev
On Mon, Jul 03, 2006 at 09:14:38AM +1000, Neil Brown wrote: However + + /* if we are using udev and auto is not set, mdadm will almost +* certainly fail, so we force it here. +*/ + if (autof == 0 access(/dev/.udevdb,F_OK) == 0) + autof=2; + I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. is /dev/.udev/db a debianism? in this case a check for both might suffice, else i will have to think harder about it. 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
[PATCH] enable auto=yes by default when using udev
Hello,
the following patch aims at solving an issue that is confusing a lot of
users.
when using udev, device files are created only when devices are
registered with the kernel, and md devices are registered only when
started.
mdadm needs the device file _before_ starting the array.
so when using udev you must add --auto=yes to the mdadm commandline or
to the ARRAY line in mdadm.conf
following patch makes auto=yes the default when using udev
L.
--
Luca Berra -- [EMAIL PROTECTED]
Communication Media Services S.r.l.
/\
\ / ASCII RIBBON CAMPAIGN
XAGAINST HTML MAIL
/ \
* Sat Jun 24 2006 Luca Berra [EMAIL PROTECTED]
- automatically create devices if using udev
--- mdadm-2.5.1/mdadm.c.autof 2006-06-02 01:51:01.0 -0400
+++ mdadm-2.5.1/mdadm.c 2006-06-24 05:17:45.0 -0400
@@ -857,6 +857,13 @@
fputs(Usage, stderr);
exit(2);
}
+
+ /* if we are using udev and auto is not set, mdadm will almost
+* certainly fail, so we force it here.
+*/
+ if (autof == 0 access(/dev/.udevdb,F_OK) == 0)
+ autof=2;
+
/* Ok, got the option parsing out of the way
* hopefully it's mostly right but there might be some stuff
* missing
@@ -873,7 +880,7 @@
fprintf(stderr, Name : an md device must be given in
this mode\n);
exit(2);
}
- if ((int)ident.super_minor == -2 autof) {
+ if ((int)ident.super_minor == -2 autof 2 ) {
fprintf(stderr, Name : --super-minor=dev is
incompatible with --auto\n);
exit(2);
}
Re: [PATCH] enable auto=yes by default when using udev
On Monday July 3, [EMAIL PROTECTED] wrote: Hello, the following patch aims at solving an issue that is confusing a lot of users. when using udev, device files are created only when devices are registered with the kernel, and md devices are registered only when started. mdadm needs the device file _before_ starting the array. so when using udev you must add --auto=yes to the mdadm commandline or to the ARRAY line in mdadm.conf following patch makes auto=yes the default when using udev The principle I'm reasonably happy with, though you can now make this the default with a line like CREATE auto=yes in mdadm.conf. However + + /* if we are using udev and auto is not set, mdadm will almost + * certainly fail, so we force it here. + */ + if (autof == 0 access(/dev/.udevdb,F_OK) == 0) + autof=2; + I'm worried that this test is not very robust. On my Debian/unstable system running used, there is no /dev/.udevdb though there is a /dev/.udev/db I guess I could test for both, but then udev might change again I'd really like a more robust check. Maybe I could test if /dev was a mount point? Any other ideas? 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: [PATCH] enable auto=yes by default when using udev
[EMAIL PROTECTED] said: Maybe I could test if /dev was a mount point? Any other ideas? there's a udevd you can check for. I don't know whether that's a better test or not. Jason - 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
