[linux-lvm] Bad disk?

[linux-lvm] Bad disk?

[Mauricio Tavares]

Yesterday I added a hard drive (to put extra stuff on it) to my ubuntu 
10.10 box and created a LVM in it. Then copied some files to it and 
restarted the machine to see if it would mount into the right 
mountpoint. It didn't. So I decided to see if it was there (vg in 
question is export):

raub@strangepork:~$ sudo vgscan
   Reading all physical volumes.  This may take a while...
   /dev/dm-0: read failed after 0 of 4096 at 429496664064: Input/output 
error
   /dev/dm-0: read failed after 0 of 4096 at 429496721408: Input/output 
error
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   /dev/dm-0: read failed after 0 of 4096 at 4096: Input/output error
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   Found volume group "export" using metadata type lvm2
   Found volume group "root" using metadata type lvm2
raub@strangepork:~$

Those dm-0 messages do not make me happy. dmesg and vgchange make me 
think the problem is on the new drive:

[  268.024593] scsi 0:0:0:0: Direct-Access     ATA      ST3500320NS 
  SN04 PQ: 0 ANSI: 5
[  268.024900] sd 0:0:0:0: [sdc] 976773168 512-byte logical blocks: (500 
GB/465 GiB)
[  268.024918] sd 0:0:0:0: Attached scsi generic sg2 type 0
[  268.024996] sd 0:0:0:0: [sdc] Write Protect is off
[  268.025003] sd 0:0:0:0: [sdc] Mode Sense: 00 3a 00 00
[  268.025046] sd 0:0:0:0: [sdc] Write cache: enabled, read cache: 
enabled, doesn't support DPO or FUA
[  268.025377]  sdc: sdc1
[  268.049853] sd 0:0:0:0: [sdc] Attached SCSI disk
[  335.467482] quiet_error: 3 callbacks suppressed
[  335.467492] Buffer I/O error on device dm-0, logical block 104857584
[  335.467540] Buffer I/O error on device dm-0, logical block 104857584
[  335.467589] Buffer I/O error on device dm-0, logical block 104857598
[  335.467615] Buffer I/O error on device dm-0, logical block 104857598
[  335.467647] Buffer I/O error on device dm-0, logical block 0
[  335.467671] Buffer I/O error on device dm-0, logical block 0
[  335.467703] Buffer I/O error on device dm-0, logical block 1
[  335.467734] Buffer I/O error on device dm-0, logical block 104857599
[  335.467762] Buffer I/O error on device dm-0, logical block 104857599
[  335.467788] Buffer I/O error on device dm-0, logical block 104857599

raub@strangepork:~$ sudo vgchange -a y
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   1 logical volume(s) in volume group "export" now active
   4 logical volume(s) in volume group "root" now active
raub@strangepork:~$

Glancing through http://readlist.com/lists/centos.org/centos/1/5704.html 
I wondered if I had the wrong file system descriptor:

raub@strangepork:~$ sudo sfdisk -l /dev/sdc

Disk /dev/sdc: 60801 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

    Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdc1          0+  60800   60801- 488384001   8e  Linux LVM
/dev/sdc2          0       -       0          0    0  Empty
/dev/sdc3          0       -       0          0    0  Empty
/dev/sdc4          0       -       0          0    0  Empty
raub@strangepork:~$

I guess that rules that out. Does that mean the disk is bad? If so, is 
there a way to retrieve the data I put in it?

Re: [linux-lvm] Bad disk?

[Phillip Susi]

On 11/10/2010 9:39 AM, Mauricio Tavares wrote:
> Yesterday I added a hard drive (to put extra stuff on it) to my ubuntu
> 10.10 box and created a LVM in it. Then copied some files to it and
> restarted the machine to see if it would mount into the right
> mountpoint. It didn't. So I decided to see if it was there (vg in
> question is export):

None of the errors you posted mention a physical disk at all, so there
isn't anything wrong with them.  To find out what dm-0 is you need to
poke around with dmsetup.

Re: [linux-lvm] Bad disk?

[Stuart D. Gathman]

On Wed, 10 Nov 2010, Mauricio Tavares wrote:

> Those dm-0 messages do not make me happy. dmesg and vgchange make me think the
> problem is on the new drive:

Those dm-0 messages are probably a logical error.  For instance, a snapshot
that is full would give those errors.  You need to tell us what dm-0 is
mapped to.  Look in /dev/mapper for starters.

> [  268.024593] scsi 0:0:0:0: Direct-Access     ATA      ST3500320NS  SN04 PQ:
> 0 ANSI: 5
> [  268.024900] sd 0:0:0:0: [sdc] 976773168 512-byte logical blocks: (500
> GB/465 GiB)
> [  268.024918] sd 0:0:0:0: Attached scsi generic sg2 type 0
> [  268.024996] sd 0:0:0:0: [sdc] Write Protect is off
> [  268.025003] sd 0:0:0:0: [sdc] Mode Sense: 00 3a 00 00
> [  268.025046] sd 0:0:0:0: [sdc] Write cache: enabled, read cache: enabled,
> doesn't support DPO or FUA
> [  268.025377]  sdc: sdc1
> [  268.049853] sd 0:0:0:0: [sdc] Attached SCSI disk

This is normal for your new disk.

> [  335.467482] quiet_error: 3 callbacks suppressed
> [  335.467492] Buffer I/O error on device dm-0, logical block 104857584
> [  335.467540] Buffer I/O error on device dm-0, logical block 104857584
> [  335.467589] Buffer I/O error on device dm-0, logical block 104857598
> [  335.467615] Buffer I/O error on device dm-0, logical block 104857598
> [  335.467647] Buffer I/O error on device dm-0, logical block 0
> [  335.467671] Buffer I/O error on device dm-0, logical block 0
> [  335.467703] Buffer I/O error on device dm-0, logical block 1
> [  335.467734] Buffer I/O error on device dm-0, logical block 104857599
> [  335.467762] Buffer I/O error on device dm-0, logical block 104857599
> [  335.467788] Buffer I/O error on device dm-0, logical block 104857599

Again, this is on dm-0, not sdc.

> raub@strangepork:~$ sudo sfdisk -l /dev/sdc
> 
> Disk /dev/sdc: 60801 cylinders, 255 heads, 63 sectors/track
> Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
> 
>    Device Boot Start     End   #cyls    #blocks   Id  System
> /dev/sdc1          0+  60800   60801- 488384001   8e  Linux LVM
> /dev/sdc2          0       -       0          0    0  Empty
> /dev/sdc3          0       -       0          0    0  Empty
> /dev/sdc4          0       -       0          0    0  Empty

This is normal, not sure what is has to do with filesystem desciptors.

Tell us exactly what you mean by "put a LVM on it".  Did you run
pvcreate?  vgcreate?  lvcreate? You might find the output of "pvs"
enlightening.  That will tell us what PVs you have created.
And list /dev/mapper so we know what dm-0 is, and include the output of "lvs".

-- 
	      Stuart D. Gathman <stuart@bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

Re: [linux-lvm] Bad disk?

[Mauricio Tavares]

On 11/10/2010 10:11 AM, Phillip Susi wrote:
> On 11/10/2010 9:39 AM, Mauricio Tavares wrote:
>> Yesterday I added a hard drive (to put extra stuff on it) to my ubuntu
>> 10.10 box and created a LVM in it. Then copied some files to it and
>> restarted the machine to see if it would mount into the right
>> mountpoint. It didn't. So I decided to see if it was there (vg in
>> question is export):
>
> None of the errors you posted mention a physical disk at all, so there
> isn't anything wrong with them.  To find out what dm-0 is you need to
> poke around with dmsetup.

	Now that might be interesting since I honestly do not know how to use 
it (and my google-fu seems weak today). But this is a bit more info I found:

raub@strangepork:~$ sudo pvs -a
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   /dev/dm-0: read failed after 0 of 4096 at 429496664064: Input/output 
error
   /dev/dm-0: read failed after 0 of 4096 at 429496721408: Input/output 
error
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   /dev/dm-0: read failed after 0 of 4096 at 4096: Input/output error
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   PV         VG     Fmt  Attr PSize   PFree
   /dev/dm-0              --        0       0
   /dev/dm-1  root   lvm2 a-   277.05g 192.55g
   /dev/dm-2              --        0       0
   /dev/dm-3              --        0       0
   /dev/dm-4              --        0       0
   /dev/dm-5              --        0       0
   /dev/ram0              --        0       0
   /dev/ram1              --        0       0
   /dev/ram10             --        0       0
   /dev/ram11             --        0       0
   /dev/ram12             --        0       0
   /dev/ram13             --        0       0
   /dev/ram14             --        0       0
   /dev/ram15             --        0       0
   /dev/ram2              --        0       0
   /dev/ram3              --        0       0
   /dev/ram4              --        0       0
   /dev/ram5              --        0       0
   /dev/ram6              --        0       0
   /dev/ram7              --        0       0
   /dev/ram8              --        0       0
   /dev/ram9              --        0       0
   /dev/root              --        0       0
   /dev/sda1              --        0       0
   /dev/sda3              --        0       0
   /dev/sdc1  export lvm2 a-   465.76g  65.76g
raub@strangepork:~$

FYI, the root vg in inside /dev/sda3, which is an encrypted partition. 
How can I find which drive /dev/dm-0 is?

Re: [linux-lvm] Bad disk?

[Ray Morris]

On 11/10/2010 11:56:24 AM, Mauricio Tavares wrote:

> How can I find which drive /dev/dm-0 is?

Try:
  cat /sys/block/dm-0/dm/name

On my system, I created dm2device so I can tell which snapshot is
full or whatever device has a problem:

# cat /usr/local/bin/dm2device
#!/bin/sh

cat /sys/block/$1/dm/name

--
Ray Morris
support@bettercgi.com

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On 11/10/2010 11:56:24 AM, Mauricio Tavares wrote:
> On 11/10/2010 10:11 AM, Phillip Susi wrote:
>> On 11/10/2010 9:39 AM, Mauricio Tavares wrote:
>>> Yesterday I added a hard drive (to put extra stuff on it) to my  
>>> ubuntu
>>> 10.10 box and created a LVM in it. Then copied some files to it and
>>> restarted the machine to see if it would mount into the right
>>> mountpoint. It didn't. So I decided to see if it was there (vg in
>>> question is export):
>> 
>> None of the errors you posted mention a physical disk at all, so  
>> there
>> isn't anything wrong with them.  To find out what dm-0 is you need to
>> poke around with dmsetup.
> 
> 	Now that might be interesting since I honestly do not know how  
> to use it (and my google-fu seems weak today). But this is a bit more  
> info I found:
> 
> raub@strangepork:~$ sudo pvs -a
>   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>   /dev/dm-0: read failed after 0 of 4096 at 429496664064:  
> Input/output error
>   /dev/dm-0: read failed after 0 of 4096 at 429496721408:  
> Input/output error
>   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>   /dev/dm-0: read failed after 0 of 4096 at 4096: Input/output error
>   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>   PV         VG     Fmt  Attr PSize   PFree
>   /dev/dm-0              --        0       0
>   /dev/dm-1  root   lvm2 a-   277.05g 192.55g
>   /dev/dm-2              --        0       0
>   /dev/dm-3              --        0       0
>   /dev/dm-4              --        0       0
>   /dev/dm-5              --        0       0
>   /dev/ram0              --        0       0
>   /dev/ram1              --        0       0
>   /dev/ram10             --        0       0
>   /dev/ram11             --        0       0
>   /dev/ram12             --        0       0
>   /dev/ram13             --        0       0
>   /dev/ram14             --        0       0
>   /dev/ram15             --        0       0
>   /dev/ram2              --        0       0
>   /dev/ram3              --        0       0
>   /dev/ram4              --        0       0
>   /dev/ram5              --        0       0
>   /dev/ram6              --        0       0
>   /dev/ram7              --        0       0
>   /dev/ram8              --        0       0
>   /dev/ram9              --        0       0
>   /dev/root              --        0       0
>   /dev/sda1              --        0       0
>   /dev/sda3              --        0       0
>   /dev/sdc1  export lvm2 a-   465.76g  65.76g
> raub@strangepork:~$
> 
> FYI, the root vg in inside /dev/sda3, which is an encrypted  
> partition. How can I find which drive /dev/dm-0 is?
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 

Re: [linux-lvm] Bad disk?

[Mauricio Tavares]

On 11/10/2010 01:58 PM, Ray Morris wrote:
> On 11/10/2010 11:56:24 AM, Mauricio Tavares wrote:
>
>> How can I find which drive /dev/dm-0 is?
>
> Try:
> cat /sys/block/dm-0/dm/name
>
> On my system, I created dm2device so I can tell which snapshot is
> full or whatever device has a problem:
>
> # cat /usr/local/bin/dm2device
> #!/bin/sh
>
> cat /sys/block/$1/dm/name
>
	Thanks!

cat /sys/block/dm-0/dm/name returned export-vms, which is /dev/sdc1.

> --
> Ray Morris
> support@bettercgi.com
>
> Strongbox - The next generation in site security:
> http://www.bettercgi.com/strongbox/
>
> Throttlebox - Intelligent Bandwidth Control
> http://www.bettercgi.com/throttlebox/
>
> Strongbox / Throttlebox affiliate program:
> http://www.bettercgi.com/affiliates/user/register.php
>
>
> On 11/10/2010 11:56:24 AM, Mauricio Tavares wrote:
>> On 11/10/2010 10:11 AM, Phillip Susi wrote:
>>> On 11/10/2010 9:39 AM, Mauricio Tavares wrote:
>>>> Yesterday I added a hard drive (to put extra stuff on it) to my ubuntu
>>>> 10.10 box and created a LVM in it. Then copied some files to it and
>>>> restarted the machine to see if it would mount into the right
>>>> mountpoint. It didn't. So I decided to see if it was there (vg in
>>>> question is export):
>>>
>>> None of the errors you posted mention a physical disk at all, so there
>>> isn't anything wrong with them. To find out what dm-0 is you need to
>>> poke around with dmsetup.
>>
>> Now that might be interesting since I honestly do not know how to use
>> it (and my google-fu seems weak today). But this is a bit more info I
>> found:
>>
>> raub@strangepork:~$ sudo pvs -a
>> /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>> /dev/dm-0: read failed after 0 of 4096 at 429496664064: Input/output
>> error
>> /dev/dm-0: read failed after 0 of 4096 at 429496721408: Input/output
>> error
>> /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>> /dev/dm-0: read failed after 0 of 4096 at 4096: Input/output error
>> /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
>> PV VG Fmt Attr PSize PFree
>> /dev/dm-0 -- 0 0
>> /dev/dm-1 root lvm2 a- 277.05g 192.55g
>> /dev/dm-2 -- 0 0
>> /dev/dm-3 -- 0 0
>> /dev/dm-4 -- 0 0
>> /dev/dm-5 -- 0 0
>> /dev/ram0 -- 0 0
>> /dev/ram1 -- 0 0
>> /dev/ram10 -- 0 0
>> /dev/ram11 -- 0 0
>> /dev/ram12 -- 0 0
>> /dev/ram13 -- 0 0
>> /dev/ram14 -- 0 0
>> /dev/ram15 -- 0 0
>> /dev/ram2 -- 0 0
>> /dev/ram3 -- 0 0
>> /dev/ram4 -- 0 0
>> /dev/ram5 -- 0 0
>> /dev/ram6 -- 0 0
>> /dev/ram7 -- 0 0
>> /dev/ram8 -- 0 0
>> /dev/ram9 -- 0 0
>> /dev/root -- 0 0
>> /dev/sda1 -- 0 0
>> /dev/sda3 -- 0 0
>> /dev/sdc1 export lvm2 a- 465.76g 65.76g
>> raub@strangepork:~$
>>
>> FYI, the root vg in inside /dev/sda3, which is an encrypted partition.
>> How can I find which drive /dev/dm-0 is?
>>
>> _______________________________________________
>> linux-lvm mailing list
>> linux-lvm@redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-lvm
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Bad disk?

[Mauricio Tavares]

On 11/10/2010 12:41 PM, Stuart D. Gathman wrote:
> On Wed, 10 Nov 2010, Mauricio Tavares wrote:
>
>> Those dm-0 messages do not make me happy. dmesg and vgchange make me think the
>> problem is on the new drive:
>
> Those dm-0 messages are probably a logical error.  For instance, a snapshot
> that is full would give those errors.  You need to tell us what dm-0 is
> mapped to.  Look in /dev/mapper for starters.
>
	Sorry for that: I did not think it would be there. But, as you said, it is:

lrwxrwxrwx 1 root root      7 2010-11-10 09:30 export-vms -> ../dm-0

the export vg is in /dev/sdc1.

>> [  268.024593] scsi 0:0:0:0: Direct-Access     ATA      ST3500320NS  SN04 PQ:
>> 0 ANSI: 5
>> [  268.024900] sd 0:0:0:0: [sdc] 976773168 512-byte logical blocks: (500
>> GB/465 GiB)
>> [  268.024918] sd 0:0:0:0: Attached scsi generic sg2 type 0
>> [  268.024996] sd 0:0:0:0: [sdc] Write Protect is off
>> [  268.025003] sd 0:0:0:0: [sdc] Mode Sense: 00 3a 00 00
>> [  268.025046] sd 0:0:0:0: [sdc] Write cache: enabled, read cache: enabled,
>> doesn't support DPO or FUA
>> [  268.025377]  sdc: sdc1
>> [  268.049853] sd 0:0:0:0: [sdc] Attached SCSI disk
>
> This is normal for your new disk.
>
>> [  335.467482] quiet_error: 3 callbacks suppressed
>> [  335.467492] Buffer I/O error on device dm-0, logical block 104857584
>> [  335.467540] Buffer I/O error on device dm-0, logical block 104857584
>> [  335.467589] Buffer I/O error on device dm-0, logical block 104857598
>> [  335.467615] Buffer I/O error on device dm-0, logical block 104857598
>> [  335.467647] Buffer I/O error on device dm-0, logical block 0
>> [  335.467671] Buffer I/O error on device dm-0, logical block 0
>> [  335.467703] Buffer I/O error on device dm-0, logical block 1
>> [  335.467734] Buffer I/O error on device dm-0, logical block 104857599
>> [  335.467762] Buffer I/O error on device dm-0, logical block 104857599
>> [  335.467788] Buffer I/O error on device dm-0, logical block 104857599
>
> Again, this is on dm-0, not sdc.
>
>> raub@strangepork:~$ sudo sfdisk -l /dev/sdc
>>
>> Disk /dev/sdc: 60801 cylinders, 255 heads, 63 sectors/track
>> Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
>>
>>     Device Boot Start     End   #cyls    #blocks   Id  System
>> /dev/sdc1          0+  60800   60801- 488384001   8e  Linux LVM
>> /dev/sdc2          0       -       0          0    0  Empty
>> /dev/sdc3          0       -       0          0    0  Empty
>> /dev/sdc4          0       -       0          0    0  Empty
>
> This is normal, not sure what is has to do with filesystem desciptors.
>
> Tell us exactly what you mean by "put a LVM on it".  Did you run
> pvcreate?  vgcreate?  lvcreate? You might find the output of "pvs"
> enlightening.  That will tell us what PVs you have created.
> And list /dev/mapper so we know what dm-0 is, and include the output of "lvs".
>
	Let me put this way, I thought I did. I mean, after creating the 
partition, setting it to LVM (8e), then running

pvcreate /dev/sdc1
vgcreate export /dev/sdc1
lvcreate -L 400G --name vms export

I used mkfs.ext4 to create partition (on /dev/mapper/export-vms) and off 
I went. Do you think I missed a step?

Re: [linux-lvm] Bad disk?

[Stuart D. Gathman]

On Wed, 10 Nov 2010, Mauricio Tavares wrote:

> > Tell us exactly what you mean by "put a LVM on it".  Did you run
> > pvcreate?  vgcreate?  lvcreate? You might find the output of "pvs"
> > enlightening.  That will tell us what PVs you have created.
> > And list /dev/mapper so we know what dm-0 is, and include the output of
> > "lvs".
> >
> 	Let me put this way, I thought I did. I mean, after creating the
> partition, setting it to LVM (8e), then running
> 
> pvcreate /dev/sdc1
> vgcreate export /dev/sdc1
> lvcreate -L 400G --name vms export
> 
> I used mkfs.ext4 to create partition (on /dev/mapper/export-vms) and off I
> went. Do you think I missed a step?

Great.  Now include output of "lvs"

BTW, if you really suspect a disk error, test for it directly.
E.g., you can run

# dd if=/dev/sdc1 of=/dev/null bs=256k

to read through the partition or

# smartctl -t long /dev/sdc

To initiate a long self test of the disk (need smartmontools installed).

A brand new disk that flunks self test is indeed defective.

However, for real physical I/O errors, there would be errors logged
in /var/log/messages referencing sdc (as opposed to dm-0), so I still
think it is a logical error.

-- 
	      Stuart D. Gathman <stuart@bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

Re: [linux-lvm] Bad disk?

[Mauricio Tavares]

On 11/11/2010 11:46 AM, Stuart D. Gathman wrote:
> On Wed, 10 Nov 2010, Mauricio Tavares wrote:
>
>>> Tell us exactly what you mean by "put a LVM on it".  Did you run
>>> pvcreate?  vgcreate?  lvcreate? You might find the output of "pvs"
>>> enlightening.  That will tell us what PVs you have created.
>>> And list /dev/mapper so we know what dm-0 is, and include the output of
>>> "lvs".
>>>
>> 	Let me put this way, I thought I did. I mean, after creating the
>> partition, setting it to LVM (8e), then running
>>
>> pvcreate /dev/sdc1
>> vgcreate export /dev/sdc1
>> lvcreate -L 400G --name vms export
>>
>> I used mkfs.ext4 to create partition (on /dev/mapper/export-vms) and off I
>> went. Do you think I missed a step?
>
> Great.  Now include output of "lvs"

raub@strangepork:~$ sudo lvs export
   /dev/dm-0: read failed after 0 of 4096 at 0: Input/output error
   LV   VG     Attr   LSize   Origin Snap%  Move Log Copy%  Convert
   vms  export -wi-a- 400.00g
raub@strangepork:~$

> BTW, if you really suspect a disk error, test for it directly.
> E.g., you can run
>
> # dd if=/dev/sdc1 of=/dev/null bs=256k
>
> to read through the partition or
>
> # smartctl -t long /dev/sdc
>
> To initiate a long self test of the disk (need smartmontools installed).
>
> A brand new disk that flunks self test is indeed defective.
>
> However, for real physical I/O errors, there would be errors logged
> in /var/log/messages referencing sdc (as opposed to dm-0), so I still
> think it is a logical error.
>