[PVE-User] DRBD sync speed

[dorsy]

DRBD related, google for DRBD resync speed :)

On 2018. 10. 10. 15:23, Adam Weremczuk wrote:
> Hi all,
>
> I'm trying out DRBD Pacemaker HA Cluster on Proxmox 5.2
>
> I have 2 identical servers connected with 2 x 1 Gbps links in 
> bond_mode balance-rr.
>
> The bond is working fine; I get a transfer rate of 150 MB/s with scp.
>
> Following this guide: 
> https://www.theurbanpenguin.com/drbd-pacemaker-ha-cluster-ubuntu-16-04/ 
> was going  smoothly up until:
>
> drbdadm -- --overwrite-data-of-peer primary r0/0
>
> cat /proc/drbd
> version: 8.4.10 (api:1/proto:86-101)
> srcversion: 17A0C3A0AF9492ED4B9A418
>  0: cs:SyncSource ro:Primary/Secondary ds:UpToDate/Inconsistent C r-----
>     ns:10944 nr:0 dw:0 dr:10992 al:8 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 
> wo:f oos:3898301536
>     [>....................] sync'ed:  0.1% (3806932/3806944)M
>     finish: 483:25:13 speed: 2,188 (2,188) K/sec
>
> The transfer rate is horribly slow and at this pace it's going to take 
> 20 days for two 4 TB volumes to sync!
>
> That's almost 15 times slower comparing with the guide video (8:30): 
> https://www.youtube.com/watch?v=WQGi8Nf0kVc
>
> The volumes have been zeroed and contain no live data yet.
>
> My sdb disks are logical drives (hardware RAID) set up as RAID50 with 
> the defaults:
>
> Strip size: 128 KB
> Access policy: RW
> Read policy: Normal
> Write policy: Write Back with BBU
> IO policy: Direct
> Drive Cache: Disable
> Disable BGI: No
>
> Performance looks good when tested with hdparm:
>
> hdparm -tT /dev/sdb1
>
> /dev/sdb1:
>  Timing cached reads:   15056 MB in  1.99 seconds = 7550.46 MB/sec
>  Timing buffered disk reads: 2100 MB in  3.00 seconds = 699.81 MB/sec
>
> The volumes have been zeroed and contain no live data yet.
>
> Any idea why the sync rate is so painfully slow and how to improve it?
>
> Regards,
> Adam
>
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