2tb-limit in dm-multipath?

2tb-limit in dm-multipath?

[Eckebrecht von Pappenheim]

Hello,

I run a setup with 2 SAN-boxes attached to a server using the multipath-tools
version 0.4.7 and kernel 2.6.17 (the qlogic-drivers do not compile against
2.6.18 ff.).

I had no problems setting this up (despite some udev-trouble due to an older
dmsetup). But when I try to access volumes > 2tb I get something like

[root@backup]/var/log> fsck /dev/san/estor02lun0p1 
fsck 1.37 (21-Mar-2005)
e2fsck 1.37 (21-Mar-2005)
The filesystem size (according to the superblock) is 1202399223 blocks
The physical size of the device is 128657399 blocks
Either the superblock or the partition table is likely to be corrupt!

Without multipath the device is accessible and fsck'ble. I suspect a 32bit-wrap
because of

[root@backup]~> bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
# 4k blocks to volume size
1202399223 * 4
4809596892
# wrap
4809596892 - (2^32)
514629596
# back to blocks
514629596 / 4
# qed...
128657399

My device map for this device is
[root@backup]/~> multipath -l 3600d0230000000000083591ea0567c00
3600d0230000000000083591ea0567c00dm-5 IFT,A24F-R2224-1
[size=4.5T][features=0][hwhandler=0]
\_ round-robin 0 [prio=0][active]
 \_ 3:0:1:0 sdp 8:240 [active][undef]

(I don't have actually a multipath for this device, but I'd like to have...)

Any idea which part of the multipath puzzle is the 32bit bottleneck?

Regards,
Eckebrecht

-- 
Eckebrecht von Pappenheim, network administration 
Heise Zeitschriften Verlag GmbH & Co KG
Helstorferstr. 7, D-30625 Hannover, FRG
E-Mail: evp@heise.de  - Tel: +49 511 5352 242  -  FAX: +49 511 5352 479
http://www.heise.de/

Re: 2tb-limit in dm-multipath?

[Bernd Zeimetz]

Hello,
> I had no problems setting this up (despite some udev-trouble due to an older
> dmsetup). But when I try to access volumes > 2tb I get something like
>   
do you have "Support for Large Block Devices" activated in your kernel
config?


Best regards,

Bernd Zeimetz

Re: 2tb-limit in dm-multipath?

[Eckebrecht von Pappenheim]

Hello,

>> I had no problems setting this up (despite some udev-trouble due to an
>> older dmsetup). But when I try to access volumes > 2tb I get something
>> like
>>   
> do you have "Support for Large Block Devices" activated in your kernel
> config?

yes, I have. I can and do use the big partitions directly without any
problems. The trouble starts when I try to use them through multipath.

Best regards,
Eckebrecht


-- 
Eckebrecht von Pappenheim, network administration 
Heise Zeitschriften Verlag GmbH & Co KG
Helstorferstr. 7, D-30625 Hannover, FRG
E-Mail: evp@heise.de  - Tel: +49 511 5352 242  -  FAX: +49 511 5352 479
http://www.heise.de/