Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello.
I didnt reply your email because:
I'm a DRBD user. I'm not in the DRBD Team.
My english is poor.
And I dont understand what is your problem, because in the email you
send the DRBD sync is aprox 680MB/s.
RAID 10 to 800MB/s is a theoretical or tested value ?
Do you test link connection ? What it is the real speed of your
connection ? I think that 680MB/s is good. The theoretical value in a
10Gb/s is 1280MB/s but real depends
You can test speed link connection with
http://eggdrop.ch/projects/bwbench/
What is you want ?
more speed in sync ??
El 08/06/15 a las 16:47, Ben RUBSON escribió:
> Hello,
>
> I am confused to ask again, but could you help me with this please ?
> I really don't know how to go further, if the behavior I would like to
> have is supported by DRBD or not...
>
> DRBD team ?
> Any support would really be appreciated.
>
> Thank you again,
>
> Best regards,
>
> Ben
>
>
>
> 2015-05-28 17:05 GMT+02:00 Ben RUBSON <ben.rubson at gmail.com
> <mailto:ben.rubson at gmail.com>>:
>
> So,
>
> I played during hours with the dynamic resync rate controller.
> Here are my settings :
>
> c-plan-ahead 10; //10ms between my 2 nodes, but minimum 1 second
> recommended here :
> https://blogs.linbit.com/p/128/drbd-sync-rate-controller/
> resync-rate 680M; //mainly ignored
> c-min-rate 400M;
> c-max-rate 680M;
> c-fill-target 20M; //my BDP is 6.8M, guides say to use a value
> between 1x and 3x BDP
>
> Resync can achieve up to 680M when there are no application IOs on
> the source.
> However, as soon as there are application IOs (writes with dd in
> my tests), resync slows down to some MB/s...
> I played with c-plan-ahead and c-fill-target without success.
> I also tested c-delay-target.
> I tried to set unplug-watermark to 16.
> My IO scheduler is already the deadline one...
>
> Well, I'm a little bit lost, I can't achieve to get resync with a
> minimum rate of 400M when there are application IOs...
>
> Here, Lars says :
> http://lists.linbit.com/pipermail/drbd-user/2011-August/016739.html
> The dynamic resync rate controller basically tries to use as much
> as c-max-rate bandwidth, but will automatically throttle, if
> - application IO on the device is detected (READ or WRITE), AND
> the estimated current resync speed is above c-min-rate
> - the amount of in-flight resync requests exceeds c-fill-target
>
> However, does DRBD throttle application IOs when resync rate is
> lower than c-min-rate ?
> According to my tests I'm not so sure.
>
>
>
> 2015-05-26 15:06 GMT+02:00 A.Rubio <aurusa at etsii.upv.es
> <mailto:aurusa at etsii.upv.es>>:
>
> Have you test these values ?
>
> https://drbd.linbit.com/users-guide/s-throughput-tuning.html
>
>
> El 26/05/15 a las 13:16, Ben RUBSON escribió:
>> RAID controller is OK yes.
>>
>> Here is a 4 steps example of the issue :
>>
>>
>>
>> ### 1 - initial state :
>>
>> Source :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 0
>> - eth1 incoming MB/s : 0
>> - eth1 outgoing MB/s : 0
>> Target :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 0
>> - eth1 incoming MB/s : 0
>> - eth1 outgoing MB/s : 0
>>
>>
>>
>> ### 2 - dd if=/dev/zero of=bigfile :
>>
>> Source :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 670
>> - eth1 incoming MB/s : 1
>> - eth1 outgoing MB/s : 670
>> Target :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 670
>> - eth1 incoming MB/s : 670
>> - eth1 outgoing MB/s : 1
>>
>>
>>
>> ### 3 - disable the link between the 2 nodes :
>>
>> Source :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 670
>> - eth1 incoming MB/s : 0
>> - eth1 outgoing MB/s : 0
>> Target :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 0
>> - eth1 incoming MB/s : 0
>> - eth1 outgoing MB/s : 0
>>
>>
>>
>> ### 4 - re-enable the link between the 2 nodes :
>>
>> Source :
>> - sdb read MB/s : ~20
>> - sdb write MB/s : ~670
>> - eth1 incoming MB/s : 1
>> - eth1 outgoing MB/s : 670
>> Target :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 670
>> - eth1 incoming MB/s : 670
>> - eth1 outgoing MB/s : 1
>> DRBD resource :
>> 1: cs:SyncTarget ro:Secondary/Primary
>> ds:Inconsistent/UpToDate C r-----
>> ns:62950732 nr:1143320132 dw:1206271712 dr:1379744185
>> al:9869 bm:6499 lo:2 pe:681 ua:1 ap:0 ep:1 wo:d oos:11883000
>> [>...................] sync'ed: 6.9% (11604/12448)M
>> finish: 0:34:22 speed: 5,756 (6,568) want: 696,320 K/sec
>>
>>
>>
>> ### values I would have expected in step 4 :
>>
>> Source :
>> - sdb read MB/s : ~400 (because of c-min-rate 400M)
>> - sdb write MB/s : ~370
>> - eth1 incoming MB/s : 1
>> - eth1 outgoing MB/s : 670
>> Target :
>> - sdb read MB/s : 0
>> - sdb write MB/s : 670
>> - eth1 incoming MB/s : 670
>> - eth1 outgoing MB/s : 1
>>
>> Why resync is totally ignored and application (dd here in the
>> example) still consumes all available IOs / bandwidth ?
>>
>>
>>
>> 2015-05-25 16:50 GMT+02:00 A.Rubio <aurusa at etsii.upv.es
>> <mailto:aurusa at etsii.upv.es>>:
>>
>> 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
>> <mailto: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 ...
>>
>> Le 12 avr. 2014 à 17:23, Ben RUBSON
>> <ben.rubson at gmail.com
>> <mailto: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 ?
>>
>
>
>
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