[Aoetools-discuss] Unbearably slow performance

[<red...@pa...>]

Hello


I'm testing out ATA-over-Ethernet, and I'm getting very poor results. On the (only) client, I can't even get read speeds above 1 megabyte per second:

[root@polaris2 glenn]# hdparm -t /dev/etherd/e1.1

/dev/etherd/e1.1:
 Timing buffered disk reads:    4 MB in  5.61 seconds = 729.67 kB/sec
[root@polaris2 glenn]# hdparm -t /dev/etherd/e1.1

/dev/etherd/e1.1:
 Timing buffered disk reads:    4 MB in  5.58 seconds = 734.14 kB/sec
[root@polaris2 glenn]# 

Meanwhile, /dev/etherd/err fills up with these messages:
     retransmit e1.1 oldtag=6ad6e492@fffee518 newtag=6ae0e518 s=003048956e79 d=001109c15506 nout=1
     retransmit e1.1 oldtag=6b0ae51a@fffee590 newtag=6b51e590 s=003048956e79 d=001109c15506 nout=1
     retransmit e1.1 oldtag=6c01e591@fffee608 newtag=711ae608 s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=7109e5a9@fffee680 newtag=711be680 s=003048956e79 d=001109c15506 nout=1
     retransmit e1.1 oldtag=7560e691@fffee716 newtag=760ce716 s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=75c4e691@fffee716 newtag=760de716 s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=79dde727@fffee7ac newtag=7a06e7ac s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=7a03e727@fffee7ac newtag=7a07e7ac s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=7be4e7b2@fffee824 newtag=7c18e824 s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=7bf5e7b2@fffee824 newtag=7c19e824 s=003048956e79 d=001109c15506 nout=2
     retransmit e1.1 oldtag=7e6de82b@fffee89c newtag=7e7ee89c s=003048956e79 d=001109c15506 nout=1
     retransmit e1.1 oldtag=0072e8a6@fffee932 newtag=00cfe932 s=003048956e79 d=001109c15506 nout=1
     retransmit e1.1 oldtag=06b0e94e@fffee9c8 newtag=06c4e9c8 s=003048956e79 d=001109c15506 nout=1

ifconfig shows 0 errors, drops, overruns, frame or carrier errors, on BOTH sides. Each side is connected using gigabit ethernet with the MTU set to 1500. On the target side I'm using vblade:

vblade 1 1 eth0 /dev/sda5

On the iniator side I'm using the aoe kernel module included with linux 2.6.27.8.

The weird part is, I can't always reproduce this. When the stars are right and I modprobe aoe, I get "normal" read speeds, which are about 75% of what the actual disk is capable of. Just for refence:

[root@galaxy glenn]# hdparm -t /dev/sda5 

/dev/sda5:
 Timing buffered disk reads:  188 MB in  3.01 seconds =  62.42 MB/sec

When using other protocols like NFS I get normal read/write speeds, so there's nothing wrong with the hardware or the network.

What else can I look at?

Thanks,


Best regards,

Glenn