Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Cache settings an I/O in RAID controller is optimal ??? Write-back,
write-through, cache enablad, I/O direct, ...
El 25/05/15 a las 11:50, Ben RUBSON escribió:
> The link between nodes is a 10Gb/s link.
> The DRBD resource is a RAID-10 array which is able to resync at up to 800M (as you can see I have lowered it to 680M in my configuration file).
>
> The "issue" here seems to be a prioritization "issue" between application IOs and resync IOs.
> Perhaps I miss-configured something ?
> Goal is to have resync rate up to 680M, with a minimum of 400M, even if there are application IOs.
> This in order to be sure to complete the resync even if there are a lot of write IOs from the application.
>
> With my simple test below, this is not the case, dd still writes at its best throughput, lowering resync rate which can’t reach 400M at all.
>
> Thank you !
>
>> Le 25 mai 2015 à 11:18, A.Rubio <aurusa at etsii.upv.es> a écrit :
>>
>> the link between nodes is ??? 1Gb/s ??? , 10Gb/s ??? ...
>>
>> the Hard Disks are ??? SATA 7200rpm ???, 10000rpm ???, SAS ???,
>> SSD ???...
>>
>> 400M to 680M with a 10Gb/s link and SAS 15.000 rpm is OK but less ...
>>
>> El dom, 24-05-2015 a las 20:43 +0200, Ben RUBSON escribió:
>>>> Le 12 avr. 2014 à 17:23, Ben RUBSON <ben.rubson at gmail.com> a écrit :
>>>>
>>>> Hello,
>>>>
>>>> Let's assume the following configuration :
>>>> disk {
>>>> c-plan-ahead 0;
>>>> resync-rate 680M;
>>>> c-min-rate 400M;
>>>> }
>>>>
>>>> Both nodes are uptodate, and on the primary, I have a test IO burst running, using dd.
>>>>
>>>> I then cut replication link for a few minutes so that secondary node will be several GB behind primary node.
>>>>
>>>> I then re-enable replication link.
>>>> What I expect here according to the configuration is that secondary node will fetch missing GB at a 400 MB/s throughput.
>>>> DRBD should then prefer resync IOs over application (dd here) IOs.
>>>>
>>>> However, it does not seems to work.
>>>> dd still writes at its best throughput, meanwhile reads are made from the primary disk between 30 and 60 MB/s to complete the resync.
>>>> Of course this is not the expected behaviour.
>>>>
>>>> Did I miss something ?
>>> Hello,
>>>
>>> Could I have your feedback please regarding this ?
>>>
>>> Thank you !
>>>
>>> Ben
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