[DRBD-user] Digest integrity check FAILED (when using MySql)

Martin Gombač martin at isg.si
Tue Jan 12 12:39:48 CET 2010



Martin Gombač wrote:
> Florian Haas wrote:
>> On 2010-01-11 19:44, Martin Gombač wrote:
>>  
>>> Hi,
>>>
>>> under heavy-to-mild mysql usage in Xen PV server hosted on drbd block
>>> device, i get the Digest integrity check FAILED. dd or copy operations
>>> seem not trigger it.
>>> I've read posts about this issue before, so i'm aware that it's saving
>>> my data and the usual ways to go about fixing it.
>>> http://lists.linbit.com/pipermail/drbd-user/2008-January/008343.html
>>> http://lists.linbit.com/pipermail/drbd-user/2009-February/011357.html
>>>
>>> First thing i did was to remove all offloaded work from network 
>>> card, to
>>> the CPU ([rx on|off] [tx on|off] [sg on|off] [tso on|off] [ufo on|off]
>>> [gso on|off] [gro on|off]) but it didn't help. Then i switched to 
>>> second
>>> network card, intel server type and it still didn't work. Offloading or
>>> not, it didn't matter. I tried two more different network cards, 
>>> just to
>>> be sure. These were the cards:
>>> # Broadcom Corporation NetXtreme BCM5721 Gigabit Ethernet PCI Express
>>> # Intel Corporation 82574L Gigabit Network Connection
>>> # Intel Corporation 82572EI Gigabit Ethernet Controller (Copper)
>>> # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
>>>
>>> The system is latest stable CentOS (5.3) running Xen. Drbd is from
>>> extras repo.
>>>     
>>
>> You're running Xen VMs on top of DRBD? Most likely guess is that these
>> errors occur in you guest domain's swap space then. Can you confirm (or
>> disprove)?
>>
>> Cheers,
>> Florian
>>
>> P.S.: Your subject is misleading. You're not running into these messages
>> "when using MySQL", but "when running MySQL inside Xen", IIUC. That's a
>> big difference. :)
>>
>>
>>   
>
> Hi Florian,
>
> that (swap thing) was my first guess so i disabled swap (file) all 
> together. I will do it again today just to confirm it 100%. Will post 
> results a bit later.
> As a note, i'm not using reiserfs and it's magic, so that can't be the 
> reason either.
>
> About MySql u're technically correct and i have had the subject like 
> that: (when using MySql under Xen PV) but preforming all other IO 
> operations i can think off on the PV, didn't result in digest 
> integrity failing, so i removed Xen out of the subject. :-) Please 
> note that there have been similar problems reported on this mailing 
> list in the past in relation to MySql without Xen.
>
> Thank you for taking the time to answer,
> Regards,
> M.
> _______________________

It seems i was waisting your time. I'm sorry. SWAP file is to blame.
Well at least now during 20 minutes of testing with swap off, i couldn't 
reproduce the failure. I don't know how i managed to get failures last 
time with swap disabled. Beer and sleep deprivation maybe? :-)

I have just another quick question. Can i safely disable integrity 
checking now, that i know that SWAP file is to blame and still be sure 
that my data is consistent all on both nodes?

Thank you and sorry for waisting your time Florian. :-)

Regards,
M.


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