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What is 2.4.0-test10: md1 has overlapping physical units with md2!

DISCUSSION George Garvey 4 participants 4 messages Nov 19, 2000 – Nov 20, 2000

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George Garvey

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Is this something to be concerned about? It sounds like a disaster waiting to happen from the message. This is on 2 systems (with similar disk setups [same other than size]).

dmesg from bootup:

Nov 18 16:31:01 mwg kernel: md driver 0.90.0 MAX_MD_DEVS=256, MAX_REAL=12  
Nov 18 16:31:01 mwg kernel: raid1 personality registered  
Nov 18 16:31:01 mwg kernel: md.c: sizeof(mdp_super_t) = 4096  
Nov 18 16:31:01 mwg kernel: autodetecting RAID arrays  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus0/target0/lun0/part1's sb offset: 524544 [events: 00000056]  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus0/target0/lun0/part3's sb offset: 4194688 [events: 00000055]  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus0/target0/lun0/part4's sb offset: 24771008 [events: 00000058]  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus1/target0/lun0/part1's sb offset: 524544 [events: 00000056]  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus1/target0/lun0/part3's sb offset: 4194688 [events: 00000055]  
Nov 18 16:31:01 mwg kernel: (read) ide/host0/bus1/target0/lun0/part4's sb offset: 24771008 [events: 00000058]  
Nov 18 16:31:01 mwg kernel: autorun ...  
Nov 18 16:31:01 mwg kernel: considering ide/host0/bus1/target0/lun0/part4 ...  
Nov 18 16:31:01 mwg kernel:   adding ide/host0/bus1/target0/lun0/part4 ...  
Nov 18 16:31:01 mwg kernel:   adding ide/host0/bus0/target0/lun0/part4 ...  
Nov 18 16:31:01 mwg kernel: created md2  
Nov 18 16:31:01 mwg kernel: bind<ide/host0/bus0/target0/lun0/part4,1>  
Nov 18 16:31:01 mwg kernel: bind<ide/host0/bus1/target0/lun0/part4,2>  
Nov 18 16:31:01 mwg kernel: running: <ide/host0/bus1/target0/lun0/part4><ide/host0/bus0/target0/lun0/part4>  
Nov 18 16:31:01 mwg kernel: now!  
Nov 18 16:31:01 mwg kernel: ide/host0/bus1/target0/lun0/part4's event counter: 00000058  
Nov 18 16:31:01 mwg kernel: ide/host0/bus0/target0/lun0/part4's event counter: 00000058  
Nov 18 16:31:01 mwg kernel: md: md2: raid array is not clean -- starting background reconstruction  
Nov 18 16:31:01 mwg kernel: md2: max total readahead window set to 124k  
Nov 18 16:31:01 mwg kernel: md2: 1 data-disks, max readahead per data-disk: 124k  
Nov 18 16:31:01 mwg kernel: raid1: device ide/host0/bus1/target0/lun0/part4 operational as mirror 1  
Nov 18 16:31:01 mwg kernel: raid1: device ide/host0/bus0/target0/lun0/part4 operational as mirror 0  
Nov 18 16:31:01 mwg kernel: raid1: raid set md2 not clean; reconstructing mirrors  
Nov 18 16:31:01 mwg kernel: raid1: raid set md2 active with 2 out of 2 mirrors  
Nov 18 16:31:01 mwg kernel: md: updating md2 RAID superblock on device  
Nov 18 16:31:01 mwg kernel: ide/host0/bus1/target0/lun0/part4 [events: 00000059](write) ide/host0/bus1/target0/lun0/part4's sb offset: 24771008  
Nov 18 16:31:01 mwg kernel: md: syncing RAID array md2  
Nov 18 16:31:01 mwg kernel: md: minimum _guaranteed_ reconstruction speed: 100 KB/sec/disc.  
Nov 18 16:31:01 mwg kernel: md: using maximum available idle IO bandwith (but not more than 100000 KB/sec) for reconstruction.  
Nov 18 16:31:01 mwg kernel: md: using 124k window, over a total of 24771008 blocks.  
Nov 18 16:31:01 mwg kernel: ide/host0/bus0/target0/lun0/part4 [events: 00000059](write) ide/host0/bus0/target0/lun0/part4's sb offset: 24771008  
Nov 18 16:31:01 mwg kernel: .  
Nov 18 16:31:01 mwg kernel: considering ide/host0/bus1/target0/lun0/part3 ...  
Nov 18 16:31:02 mwg kernel:   adding ide/host0/bus1/target0/lun0/part3 ...  
Nov 18 16:31:02 mwg kernel:   adding ide/host0/bus0/target0/lun0/part3 ...  
Nov 18 16:31:02 mwg kernel: created md1  
Nov 18 16:31:02 mwg kernel: bind<ide/host0/bus0/target0/lun0/part3,1>  
Nov 18 16:31:02 mwg kernel: bind<ide/host0/bus1/target0/lun0/part3,2>  
Nov 18 16:31:02 mwg kernel: running: <ide/host0/bus1/target0/lun0/part3><ide/host0/bus0/target0/lun0/part3>  
Nov 18 16:31:02 mwg kernel: now!  
Nov 18 16:31:02 mwg kernel: ide/host0/bus1/target0/lun0/part3's event counter: 00000055  
Nov 18 16:31:02 mwg kernel: ide/host0/bus0/target0/lun0/part3's event counter: 00000055  
Nov 18 16:31:02 mwg kernel: md: md1: raid array is not clean -- starting background reconstruction  
Nov 18 16:31:02 mwg kernel: md1: max total readahead window set to 124k  
Nov 18 16:31:02 mwg kernel: md1: 1 data-disks, max readahead per data-disk: 124k  
Nov 18 16:31:02 mwg kernel: raid1: device ide/host0/bus1/target0/lun0/part3 operational as mirror 1  
Nov 18 16:31:02 mwg kernel: raid1: device ide/host0/bus0/target0/lun0/part3 operational as mirror 0  
Nov 18 16:31:02 mwg kernel: raid1: raid set md1 not clean; reconstructing mirrors  
Nov 18 16:31:02 mwg kernel: raid1: raid set md1 active with 2 out of 2 mirrors  
Nov 18 16:31:02 mwg kernel: md: updating md1 RAID superblock on device  
Nov 18 16:31:02 mwg kernel: ide/host0/bus1/target0/lun0/part3 [events: 00000056](write) ide/host0/bus1/target0/lun0/part3's sb offset: 4194688  
Nov 18 16:31:02 mwg kernel: md: serializing resync, md1 has overlapping physical units with md2!  
Nov 18 16:31:02 mwg kernel: ide/host0/bus0/target0/lun0/part3 [events: 00000056](write) ide/host0/bus0/target0/lun0/part3's sb offset: 4194688  
Nov 18 16:31:02 mwg kernel: .  
Nov 18 16:31:02 mwg kernel: considering ide/host0/bus1/target0/lun0/part1 ...  
Nov 18 16:31:02 mwg kernel:   adding ide/host0/bus1/target0/lun0/part1 ...  
Nov 18 16:31:02 mwg kernel:   adding ide/host0/bus0/target0/lun0/part1 ...  
Nov 18 16:31:02 mwg kernel: created md0  
Nov 18 16:31:02 mwg kernel: bind<ide/host0/bus0/target0/lun0/part1,1>  
Nov 18 16:31:02 mwg kernel: bind<ide/host0/bus1/target0/lun0/part1,2>  
Nov 18 16:31:02 mwg kernel: running: <ide/host0/bus1/target0/lun0/part1><ide/host0/bus0/target0/lun0/part1>  
Nov 18 16:31:02 mwg kernel: now!  
Nov 18 16:31:02 mwg kernel: ide/host0/bus1/target0/lun0/part1's event counter: 00000056  
Nov 18 16:31:02 mwg kernel: ide/host0/bus0/target0/lun0/part1's event counter: 00000056  
Nov 18 16:31:02 mwg kernel: md: md0: raid array is not clean -- starting background reconstruction  
Nov 18 16:31:02 mwg kernel: md0: max total readahead window set to 124k  
Nov 18 16:31:02 mwg kernel: md0: 1 data-disks, max readahead per data-disk: 124k  
Nov 18 16:31:02 mwg kernel: raid1: device ide/host0/bus1/target0/lun0/part1 operational as mirror 1  
Nov 18 16:31:02 mwg kernel: raid1: device ide/host0/bus0/target0/lun0/part1 operational as mirror 0  
Nov 18 16:31:02 mwg kernel: raid1: raid set md0 not clean; reconstructing mirrors  
Nov 18 16:31:02 mwg kernel: raid1: raid set md0 active with 2 out of 2 mirrors  
Nov 18 16:31:02 mwg kernel: md: updating md0 RAID superblock on device  
Nov 18 16:31:02 mwg kernel: ide/host0/bus1/target0/lun0/part1 [events: 00000057](write) ide/host0/bus1/target0/lun0/part1's sb offset: 524544  
Nov 18 16:31:02 mwg kernel: md: serializing resync, md0 has overlapping physical units with md2!  
Nov 18 16:31:02 mwg kernel: ide/host0/bus0/target0/lun0/part1 [events: 00000057](write) ide/host0/bus0/target0/lun0/part1's sb offset: 524544  
Nov 18 16:31:02 mwg kernel: .  
Nov 18 16:31:02 mwg kernel: ... autorun DONE.

fdisk:

	/dev/hda:

kernel version 132096

Command (m for help):
Disk /dev/hda: 16 heads, 63 sectors, 59554 cylinders Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1      1041    524632+  fd  Linux raid autodetect
/dev/hda2          1042      2082    524664   82  Linux swap
/dev/hda3          2083     10405   4194792   fd  Linux raid autodetect
/dev/hda4         10406     59554  24771096   fd  Linux raid autodetect

Command (m for help):

	/dev/hdc:

kernel version 132096

Command (m for help):
Disk /dev/hdc: 16 heads, 63 sectors, 59554 cylinders Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hdc1             1      1041    524632+  fd  Linux raid autodetect
/dev/hdc2          1042      2082    524664   82  Linux swap
/dev/hdc3          2083     10405   4194792   fd  Linux raid autodetect
/dev/hdc4         10406     59554  24771096   fd  Linux raid autodetect

Command (m for help):

/etc/raidtab:
raiddev /dev/md/0

	raid-level		1
	nr-raid-disks		2
	nr-spare-disks		0
	chunk-size		32
	persistent-superblock	1
	device			/dev/ide/host0/bus0/target0/lun0/part1
	raid-disk		0
	device			/dev/ide/host0/bus1/target0/lun0/part1
	raid-disk		1
raiddev	/dev/md/1
	raid-level		1
	nr-raid-disks		2
	nr-spare-disks		0
	chunk-size		32
	persistent-superblock	1
	device			/dev/ide/host0/bus0/target0/lun0/part3
	raid-disk		0
	device			/dev/ide/host0/bus1/target0/lun0/part3
	raid-disk		1
raiddev	/dev/md/2
	raid-level		1
	nr-raid-disks		2
	nr-spare-disks		0
	chunk-size		32
	persistent-superblock	1
	device			/dev/ide/host0/bus0/target0/lun0/part4
	raid-disk		0
	device			/dev/ide/host0/bus1/target0/lun0/part4
	raid-disk		1

/proc/mdstat:
Personalities : [raid1]
read_ahead 1024 sectors
md0 : active raid1 ide/host0/bus1/target0/lun0/part1[1] ide/host0/bus0/target0/lun0/part1[0]

      524544 blocks [2/2] [UU]

md1 : active raid1 ide/host0/bus1/target0/lun0/part3[1] ide/host0/bus0/target0/lun0/part3[0]

      4194688 blocks [2/2] [UU]

md2 : active raid1 ide/host0/bus1/target0/lun0/part4[1] ide/host0/bus0/target0/lun0/part4[0]

      24771008 blocks [2/2] [UU]

unused devices: <none>
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#1 lore raw
Quoted 3 lines · George Garvey

Is this something to be concerned about? It sounds like a disaster waiting to happen from the message. This is on 2 systems (with similar disk setups [same other than size]).

Nothing to worry. (I got worried also when I saw it the first time)

Quoted 1 line
Nov 18 16:31:02 mwg kernel: md: serializing resync,

md0 has overlapping physical units with md2!

It is perhaps poorly worded -- multiple MD "devices" using same physical devices, although they are not on overlapped partitions, do get that message.

It means simply that if those two were running reconstruction simultaneously, they would cause seeking back&forth over the device.
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#2 lore raw
In reply to George Garvey
Quoted 5 lines · George Garvey

Is this something to be concerned about? It sounds like a disaster waiting to happen from the message. This is on 2 systems (with similar disk setups [same other than size]).

Nov 18 16:31:02 mwg kernel: md: serializing resync, md1 has overlapping physical units with md2!

Nope, nothing to worry about -- it's just a bad choice of wording ;)

What it means is that some partititions in md1 and md2 are on the same disk, and that the md-code will not do the reconstruction of these arrays in parallel [of course, for performance reasons].

Regards,

Signature · 5 lines
Jasper Spaans  <[email protected]>
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#3 lore raw

Re: [PATCH] Re: What is 2.4.0-test10: md1 has overlapping physical unitswith md2!

In reply to George Garvey
Quoted 11 lines · Neil Brown

Linus, Ingo:

the attached patch, modifies a warning message in md.c which seems to often cause confusion - the following email includes one example there-of (there have been others over the months).

Hopefully the new text is clearer.

(patch against 2.4.0-test11-pre7)

There is a 'has' left in the text of the corrected line.

Quoted 2 lines

NeilBrown

This patch will has it fixed:

Marc

drivers/md/md.c 2000/11/20 00:44:19 1.3 renamed from drivers/md/md.c 2000/11/20 00:33:08 1.2 +1 -1
@@ -3279,7 +3279,7 @@
                if (mddev2 == mddev)
                        continue;
                if (mddev2->curr_resync && match_mddev_units(mddev,mddev2)) {
-                       printk(KERN_INFO "md: serializing resync, md%d has overlapping physical units with md%d!\n", mdidx(mddev), mdidx(mddev2));
+                       printk(KERN_INFO "md: serializing resync, md%d shares one or more physical units with md%d!\n", mdidx(mddev), mdidx(mddev2));
                        serialize = 1;
                        break;
                }
Signature · 9 lines
Marc Mutz <[email protected]>     http://EncryptionHOWTO.sourceforge.net/
University of Bielefeld, Dep. of Mathematics / Dep. of Physics

PGP-keyID's:   0xd46ce9ab (RSA), 0x7ae55b9e (DSS/DH)

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