[ClusterLabs] Antw: [EXT] DRBD Dual Primary Write Speed Extremely Slow

[Ulrich Windl]

Hi!

If you have planty of RAM you could configure an iSCSI disk using a ram disk and try how much I/O you get from there.
Maybe you issue is not-su-much DRBD related. However when my local MD-RAID1 resyncs with about 120MB/s (spinning disks), the system also is hardly usable.

Regards,
Ulrich

>>> Tyler Phillippe via Users <users at clusterlabs.org> schrieb am 13.11.2022 um
19:26 in Nachricht <NGmE_x7--3-9 at tutamail.com>:
> Hello all,
> 
> I have setup a Linux cluster on 2x CentOS 8 Stream machines - it has 
> resources to manage a dual primary, GFS2 DRBD setup. DRBD and the cluster 
> have a diskless witness. Everything works fine - I have the dual primary DRBD 
> working and it is able to present an iSCSI LUN out to my LAN. However, the 
> DRBD write speed is terrible. The backing DRBD disks (HDD) are RAID10 using 
> mdadm and they (re)sync at around 150MB/s. DRBD verify has been limited to 
> 100MB/s, but left untethered, it will get to around 140MB/s. If I write data 
> to the iSCSI LUN, I only get about 10-15MB/s. Here's the DRBD 
> global_common.conf - these are exactly the same on both machines:
> 
> global {
>         usage-count no;
>         udev-always-use-vnr;
> }
> 
> common {
>         handlers {
>         }
> 
>         startup {
>                 wfc-timeout 5;
>                 degr-wfc-timeout 5;
>         }
> 
>         options {
>                 auto-promote yes;
>                 quorum 1;
>                 on-no-data-accessible suspend-io;
>                 on-no-quorum suspend-io;
>         }
> 
>         disk {
>                 al-extents 4096;
>                 al-updates yes;
>                 no-disk-barrier;
>                 disk-flushes;
>                 on-io-error detach;
>                 c-plan-ahead 0;
>                 resync-rate 100M;
>         }
> 
>         net {
>                 protocol C;
>                 allow-two-primaries yes;
>                 cram-hmac-alg "sha256";
>                 csums-alg "sha256";
>                 verify-alg "sha256";
>                 shared-secret "secret123";
>                 max-buffers 36864;
>                 rcvbuf-size 5242880;
>                 sndbuf-size 5242880;
>         }
> }
> 
> Respectfully,
>  Tyler