Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
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 ?
>
>
>
> Thank you,
>
> Ben
>
>
>
> 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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