Re: [zfs-discuss] diagnosing read performance problem
Ok, I have recieved a new set of NICs and a new switch and the problem still remains. Just for something to do I ran some tests: Copying a 200Mb file over scp from the main problem workstation to a totally unrelated gentoo linux box. Absolutely no problems. So I thought it was down to the zfs fileserver. Then I ran the same test to the zfs filer just to check. Absolutely no problems again!$%?%^ I may just be getting light-headed from the hair pulling, but it seems that the problem only occurs when the traffic is going thru the CIFS server. I'm going to write a new thread to cifs-discuss and provide them some captures, maybe they have a clue why this might happen. I'm also going to switch back to the snv_95 BE I still have on the server, it's possible it might have some effect. Thanks Matt pgpdK9z30ugR8.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Well, somehow it's fixed: Since putting in the new Intel card, the transfer from the box dropped so badly, I couldn't even copy a snoop from it. So I removed the dohwchksum line from /etc/system and rebooted. Then just to clean up a bit I disabled the onboard NICs in the bios. Now I'm still seeing the duplicate ACKs and the checksum errors from that client, but the transfers have sped right up. Video playback and all other copying from the server are now working again without any problems so far. Thanks to all that have contributed to this thread, it really did help me organise my thoughts. Matt pgpVCuBqFE9Pi.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt Well this time you have filtered out any SSH traffic on port 22 successfully. But I'm still only seeing half of the conversation! I see packets sent from client to server. That is from source: 10.194.217.12 to destination: 10.194.217.3 So a different client IP this time And the Duplicate ACK packets (often long bursts) are back in this capture. I've looked at these a little bit more carefully this time, and I now notice it's using the 'TCP selective acknowledgement' feature (SACK) on those packets. Now this is not something I've come across before, so I need to do some googling! SACK is defined in RFC1208. http://www.ietf.org/rfc/rfc2018.txt I found this explanation of when SACK is used: http://thenetworkguy.typepad.com/nau/2007/10/one-of-the-most.html http://thenetworkguy.typepad.com/nau/2007/10/tcp-selective-a.html This seems to indicate these 'SACK' packets are triggered as a result of 'lost packets', in this case, it must be the packets sent back from your server to the client, that is during your video playback. Of course I'm not seeing ANY of those packets in this capture because there are none captured from server to client! I'm still not sure why you cannot seem to capture these packets! Oh, by the way, I probably should advise you to run... # netstat -i ..on the OpenSolaris box, to see if any errors are being counted on the network interface. Are you still seeing the link going up/down in '/var/admin/message'? You are never going to do any good while that is happening. I think you need to try a different network card in the server. Regards Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Nigel Smith wrote: Hi Matt Well this time you have filtered out any SSH traffic on port 22 successfully. But I'm still only seeing half of the conversation! Grr this is my day, I think I know what the problem was...user error as I'm not used to snoop. I see packets sent from client to server. That is from source: 10.194.217.12 to destination: 10.194.217.3 So a different client IP this time And the Duplicate ACK packets (often long bursts) are back in this capture. I've looked at these a little bit more carefully this time, and I now notice it's using the 'TCP selective acknowledgement' feature (SACK) on those packets. Now this is not something I've come across before, so I need to do some googling! SACK is defined in RFC1208. http://www.ietf.org/rfc/rfc2018.txt I found this explanation of when SACK is used: http://thenetworkguy.typepad.com/nau/2007/10/one-of-the-most.html http://thenetworkguy.typepad.com/nau/2007/10/tcp-selective-a.html This seems to indicate these 'SACK' packets are triggered as a result of 'lost packets', in this case, it must be the packets sent back from your server to the client, that is during your video playback. Well thats a bit above me. I can understand the lost packets though, it sounds about right for the situation. Of course I'm not seeing ANY of those packets in this capture because there are none captured from server to client! I'm still not sure why you cannot seem to capture these packets! I think I know the problem, I thought I should enable promiscuous mode, so I quickly scanned the help output and added the -P switch. However that does the opposide of what I thought and takes the snoop out of promiscuous mode. Oh, by the way, I probably should advise you to run... # netstat -i Yes one of the previous replies to this thread advised me to try that. The count does increase, however quite slowly to me. After being up for 6 hours with a few video playback tests the Oerr count sits at 92 currently. ..on the OpenSolaris box, to see if any errors are being counted on the network interface. Are you still seeing the link going up/down in '/var/admin/message'? You are never going to do any good while that is happening. I think you need to try a different network card in the server. Strangely the link up/down problem was only present on the second switch I tried (which works perfectly for other connections). On the first switch the link appears stable at first glance however we're getting these duplicate acks, and checksum errors (although the csums might be caused by the hardware offloading of that client as you pointed out). I've got a couple of brand new Intel Pro 1000s and a new switch arriving by courier tomorrow morning, so with any luck I should see some difference. I'm getting a bit busy but I will attempt to make another snoop *without* disabling promiscuous mode. Thanks for all your input Matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Tue, Oct 28, 2008 at 05:30:55PM -0700, Nigel Smith wrote: Hi Matt. Ok, got the capture and successfully 'unzipped' it. (Sorry, I guess I'm using old software to do this!) I see 12840 packets. The capture is a TCP conversation between two hosts using the SMB aka CIFS protocol. 10.194.217.10 is the client - Presumably Windows? 10.194.217.3 is the server - Presumably OpenSolaris - CIFS server? All correct so far Using WireShark, Menu: 'Statistics Endpoints' show: The Client has transmitted 4849 packets, and the Server has transmitted 7991 packets. Menu: 'Analyze Expert info Composite': The 'Errors' tab shows: 4849 packets with a 'Bad TCP checksum' error - These are all transmitted by the Client. (Apply a filter of 'ip.src_host == 10.194.217.10' to confirm this.) The 'Notes' tab shows: ..numerous 'Duplicate Ack's' For example, for 60 different ACK packets, the exact same packet was re-transmitted 7 times! Packet #3718 was duplicated 17 times. Packet #8215 was duplicated 16 times. packet #6421 was duplicated 15 times, etc. These bursts of duplicate ACK packets are all coming from the client side. This certainly looks strange to me - I've not seen anything like this before. It's not going to help the speed to unnecessarily duplicate packets like that, and these burst are often closely followed by a short delay, ~0.2 seconds. And as far as I can see, it looks to point towards the client as the source of the problem. If you are seeing the same problem with other client PC, then I guess we need to suspect the 'switch' that connects them. I have another switch on the way to move to. I will see if this helps. Thanks for your input Matt pgpPpxSVqiW79.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Tue, Oct 28, 2008 at 05:45:48PM -0700, Richard Elling wrote: I replied to Matt directly, but didn't hear back. It may be a driver issue with checksum offloading. Certainly the symptoms are consistent. To test with a workaround see http://bugs.opensolaris.org/view_bug.do?bug_id=6686415 Hi, Sorry for not replying, we had some problems with our email provider yesterday and I was up all night restoring backups. I did try the workaround, but it didn't have any effect, presumbably because it's not using the rge driver as you stated before. I'll try swapping the switch out and post back my results. Many Thanks Matt pgphN0KxBmHEz.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Matt Harrison wrote: On Tue, Oct 28, 2008 at 05:45:48PM -0700, Richard Elling wrote: I replied to Matt directly, but didn't hear back. It may be a driver issue with checksum offloading. Certainly the symptoms are consistent. To test with a workaround see http://bugs.opensolaris.org/view_bug.do?bug_id=6686415 Hi, Sorry for not replying, we had some problems with our email provider yesterday and I was up all night restoring backups. I did try the workaround, but it didn't have any effect, presumbably because it's not using the rge driver as you stated before. The dohwcksum is not an rge option, it is an ip option (hence it is named ip:dohwcksum) and it transcends NIC drivers. But if that didn't fix anything, then you should be able to safely ignore it. I'll try swapping the switch out and post back my results. Yeah, I've seen this sort of thing before, too. I once had a switch that lost its mind and wouldn't let big packets through unscathed. We could telnet, ping, ftp, and do all sorts of things through the switch, but we couldn't push NFS through. These sorts of failures can be difficult to isolate. -- richard ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt Can you just confirm if that Ethernet capture file, that you made available, was done on the client, or on the server. I'm beginning to suspect you did it on the client. You can get a capture file on the server (OpenSolaris) using the 'snoop' command, as per one of my previous emails. You can still view the capture file with WireShark as it supports the 'snoop' file format. Normally it would not be too important where the capture was obtained, but here, where something strange is happening, it could be critical to understanding what is going wrong and where. It would be interesting to do two separate captures - one on the client and the one on the server, at the same time, as this would show if the switch was causing disruption. Try to have the clocks on the client server synchronised as close as possible. Thanks Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Wed, Oct 29, 2008 at 10:01:09AM -0700, Nigel Smith wrote: Hi Matt Can you just confirm if that Ethernet capture file, that you made available, was done on the client, or on the server. I'm beginning to suspect you did it on the client. That capture was done from the client You can get a capture file on the server (OpenSolaris) using the 'snoop' command, as per one of my previous emails. You can still view the capture file with WireShark as it supports the 'snoop' file format. I am uploading a snoop from the server to http://distfiles.genestate.com/snoop.zip Please note this snoop will include traffic to ssh as I can't work out how to filter that out :P Normally it would not be too important where the capture was obtained, but here, where something strange is happening, it could be critical to understanding what is going wrong and where. It would be interesting to do two separate captures - one on the client and the one on the server, at the same time, as this would show if the switch was causing disruption. Try to have the clocks on the client server synchronised as close as possible. Clocks are synced via ntp as we're using Active Directory with CIFS. On another note, I've just moved the offending network to another switch and it's even worse I think. I've noticed that under high load, the link light for the server's connection blinks on and off, not quite steadily but about every 2 seconds. This appears in /var/adm/messages: Oct 29 18:24:22 exodus mac: [ID 435574 kern.info] NOTICE: rtls0 link up, 100 Mbps, full duplex Oct 29 18:24:24 exodus mac: [ID 486395 kern.info] NOTICE: rtls0 link down Oct 29 18:24:25 exodus mac: [ID 435574 kern.info] NOTICE: rtls0 link up, 100 Mbps, full duplex Oct 29 18:24:27 exodus mac: [ID 486395 kern.info] NOTICE: rtls0 link down Oct 29 18:24:28 exodus mac: [ID 435574 kern.info] NOTICE: rtls0 link up, 100 Mbps, full duplex Oct 29 18:24:30 exodus mac: [ID 486395 kern.info] NOTICE: rtls0 link down Oct 29 18:24:31 exodus mac: [ID 435574 kern.info] NOTICE: rtls0 link up, 100 Mbps, full duplex I think it's got to be the NIC, the network runs full duplex quite happily so I don't think its an auto-neg problem. Thanks for sticking with this :) Matt pgpgEL3gweH2e.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt In your previous capture, (which you have now confirmed was done on the Windows client), all those 'Bad TCP checksum' packets sent by the client, are explained, because you must be doing hardware TCP checksum offloading on the client network adaptor. WireShark will capture the packets before that hardware calculation is done, so the checksum all appear to be wrong, as they have not yet been calculated! http://wiki.wireshark.org/TCP_checksum_offload http://www.wireshark.org/docs/wsug_html_chunked/ChAdvChecksums.html Ok, so lets look at the new capture, 'snoop'ed on the OpenSolaris box. I was surprised how small that snoop capture file was - only 753400 bytes after unzipping. I soon realized why... The strange thing is that I'm only seeing half of the conversation! I see packets sent from client to server. That is from source: 10.194.217.10 to destination: 10.194.217.3 I can also see some packets from source: 10.194.217.5 (Your AD domain controller) to destination 10.194.217.3 But you've not capture anything transmitted from your OpenSolaris server - source: 10.194.217.3 (I checked, and I did not have any filters applied in WireShark that would cause the missing half!) Strange! I'm not sure how you did that. The half of the conversation that I can see looks fine - there does not seem to be any problem. I'm not seeing any duplication of ACK's from the client in this capture. (So again somewhat strange, unless you've fixed the problem!) I'm assuming your using a single network card in the Solaris server, but maybe you had better just confirm that. Regarding not capturing SSH traffic and only capturing traffic from ( hopefully to) the client, try this: # snoop -o test.cap -d rtls0 host 10.194.217.10 and not port 22 Regarding those 'link down', 'link up' messages, '/var/adm/messages'. I can tie up some of those events with your snoop capture file, but it just shows that no packets are being received while the link is down, which is exactly what you would expect. But dropping the link for a second will surely disrupt your video playback! If the switch is ok, and the cable from the switch is ok, then it does now point towards the network card in the OpenSolaris box. Maybe as simple as a bad mechanical connection on the cable socket BTW, just run '/usr/X11/bin/scanpci' and identify the 'vendor id' and 'device id' for the network card, just in case it turns out to be a driver bug. Regards Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Wed, Oct 29, 2008 at 05:32:39PM -0700, Nigel Smith wrote: Hi Matt In your previous capture, (which you have now confirmed was done on the Windows client), all those 'Bad TCP checksum' packets sent by the client, are explained, because you must be doing hardware TCP checksum offloading on the client network adaptor. WireShark will capture the packets before that hardware calculation is done, so the checksum all appear to be wrong, as they have not yet been calculated! I know that the client I was using has an nForce board with nVidia network controllers. There is an option to offload to hardware but I believe that was disabled. The strange thing is that I'm only seeing half of the conversation! I see packets sent from client to server. That is from source: 10.194.217.10 to destination: 10.194.217.3 I can also see some packets from source: 10.194.217.5 (Your AD domain controller) to destination 10.194.217.3 But you've not capture anything transmitted from your OpenSolaris server - source: 10.194.217.3 (I checked, and I did not have any filters applied in WireShark that would cause the missing half!) Strange! I'm not sure how you did that. I believe i was using the wrong filter expression...my bad :( The half of the conversation that I can see looks fine - there does not seem to be any problem. I'm not seeing any duplication of ACK's from the client in this capture. (So again somewhat strange, unless you've fixed the problem!) I'm assuming your using a single network card in the Solaris server, but maybe you had better just confirm that. Confirmed, there is a single PCI NIC that i'm using (there is the dual onboard but they don't work for me anymore). Regarding not capturing SSH traffic and only capturing traffic from ( hopefully to) the client, try this: # snoop -o test.cap -d rtls0 host 10.194.217.10 and not port 22 Much better thanks. I am attaching a second snoop from the server with the full conversation. http://distfiles.genestate.com/snoop2.zip Incidentally, this is talking to a different client, which although doesn't show checksum errors, does still have a load of duplicate ACKs. If this confuses the issue, I can do it from the old client as soon as it becomes free. Regarding those 'link down', 'link up' messages, '/var/adm/messages'. I can tie up some of those events with your snoop capture file, but it just shows that no packets are being received while the link is down, which is exactly what you would expect. But dropping the link for a second will surely disrupt your video playback! If the switch is ok, and the cable from the switch is ok, then it does now point towards the network card in the OpenSolaris box. Maybe as simple as a bad mechanical connection on the cable socket Very possible. I have an Intell Pro 1000 and a new GB switch on the way. BTW, just run '/usr/X11/bin/scanpci' and identify the 'vendor id' and 'device id' for the network card, just in case it turns out to be a driver bug. pci bus 0x0001 cardnum 0x06 function 0x00: vendor 0x10ec device 0x8139 Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ and the two onboards that no longer function: pci bus 0x cardnum 0x08 function 0x00: vendor 0x10de device 0x0373 nVidia Corporation MCP55 Ethernet pci bus 0x cardnum 0x09 function 0x00: vendor 0x10de device 0x0373 nVidia Corporation MCP55 Ethernet Thanks Matt pgpG9O5VYjefY.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Mon, Oct 27, 2008 at 06:18:59PM -0700, Nigel Smith wrote: Hi Matt Unfortunately, I'm having problems un-compressing that zip file. I tried with 7-zip and WinZip reports this: skipping _1_20081027010354.cap: this file was compressed using an unknown compression method. Please visit www.winzip.com/wz54.htm for more information. The compression method used for this file is 98. Please can you check it out, and if necessary use a more standard compression algorithm. Download File Size was 8,782,584 bytes. Apologies, I had let winzip compress it with whatever it thought was best, apparently this was the best method for size, not compatibility. There's a new upload under the same URL compressed with 2.0 compatible compression. Fingers crossed that works better for you. Thanks Matt pgphON3KUfHQn.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt. Ok, got the capture and successfully 'unzipped' it. (Sorry, I guess I'm using old software to do this!) I see 12840 packets. The capture is a TCP conversation between two hosts using the SMB aka CIFS protocol. 10.194.217.10 is the client - Presumably Windows? 10.194.217.3 is the server - Presumably OpenSolaris - CIFS server? Using WireShark, Menu: 'Statistics Endpoints' show: The Client has transmitted 4849 packets, and the Server has transmitted 7991 packets. Menu: 'Analyze Expert info Composite': The 'Errors' tab shows: 4849 packets with a 'Bad TCP checksum' error - These are all transmitted by the Client. (Apply a filter of 'ip.src_host == 10.194.217.10' to confirm this.) The 'Notes' tab shows: ..numerous 'Duplicate Ack's' For example, for 60 different ACK packets, the exact same packet was re-transmitted 7 times! Packet #3718 was duplicated 17 times. Packet #8215 was duplicated 16 times. packet #6421 was duplicated 15 times, etc. These bursts of duplicate ACK packets are all coming from the client side. This certainly looks strange to me - I've not seen anything like this before. It's not going to help the speed to unnecessarily duplicate packets like that, and these burst are often closely followed by a short delay, ~0.2 seconds. And as far as I can see, it looks to point towards the client as the source of the problem. If you are seeing the same problem with other client PC, then I guess we need to suspect the 'switch' that connects them. Ok, that's my thoughts conclusion for now. Maybe you could get some more snoop captures with other clients, and with a different switch, and do a similar analysis. Regards Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
I replied to Matt directly, but didn't hear back. It may be a driver issue with checksum offloading. Certainly the symptoms are consistent. To test with a workaround see http://bugs.opensolaris.org/view_bug.do?bug_id=6686415 -- richard Nigel Smith wrote: Hi Matt. Ok, got the capture and successfully 'unzipped' it. (Sorry, I guess I'm using old software to do this!) I see 12840 packets. The capture is a TCP conversation between two hosts using the SMB aka CIFS protocol. 10.194.217.10 is the client - Presumably Windows? 10.194.217.3 is the server - Presumably OpenSolaris - CIFS server? Using WireShark, Menu: 'Statistics Endpoints' show: The Client has transmitted 4849 packets, and the Server has transmitted 7991 packets. Menu: 'Analyze Expert info Composite': The 'Errors' tab shows: 4849 packets with a 'Bad TCP checksum' error - These are all transmitted by the Client. (Apply a filter of 'ip.src_host == 10.194.217.10' to confirm this.) The 'Notes' tab shows: ..numerous 'Duplicate Ack's' For example, for 60 different ACK packets, the exact same packet was re-transmitted 7 times! Packet #3718 was duplicated 17 times. Packet #8215 was duplicated 16 times. packet #6421 was duplicated 15 times, etc. These bursts of duplicate ACK packets are all coming from the client side. This certainly looks strange to me - I've not seen anything like this before. It's not going to help the speed to unnecessarily duplicate packets like that, and these burst are often closely followed by a short delay, ~0.2 seconds. And as far as I can see, it looks to point towards the client as the source of the problem. If you are seeing the same problem with other client PC, then I guess we need to suspect the 'switch' that connects them. Ok, that's my thoughts conclusion for now. Maybe you could get some more snoop captures with other clients, and with a different switch, and do a similar analysis. Regards Nigel Smith ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt Unfortunately, I'm having problems un-compressing that zip file. I tried with 7-zip and WinZip reports this: skipping _1_20081027010354.cap: this file was compressed using an unknown compression method. Please visit www.winzip.com/wz54.htm for more information. The compression method used for this file is 98. Please can you check it out, and if necessary use a more standard compression algorithm. Download File Size was 8,782,584 bytes. Thanks Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Sat, Oct 25, 2008 at 06:50:46PM -0700, Nigel Smith wrote:
Hi Matt
What chipset is your PCI network card?
(obviously, it not Intel, but what is it?)
Do you know which driver the card is using?
I believe it's some sort of Realtek (8139 probably). It's coming up as rtls0
You say '..The system was fine for a couple of weeks..'.
At that point did you change any software - do any updates or upgrades?
For instance, did you upgrade to a new build of OpenSolaris?
No, since the original problem with the onboard NICs it hasn't been upgraded
or anything.
If not, then I would guess it's some sort of hardware problem.
Can you try different cables and a different switch - anything
in the path between client server is suspect.
Have tried different cables and switch ports, I will try a different switch
as soon as I can get some space on one of the others.
A mismatch of Ethernet duplex settings can cause problems - are
you sure this is Ok.
Not 100% sure, but I will check as best I can.
To get an idea of how the network is running try this:
On the Solaris box, do an Ethernet capture with 'snoop' to a file.
http://docs.sun.com/app/docs/doc/819-2240/snoop-1m?a=view
# snoop -d {device} -o {filename}
.. then while capturing, try to play your video file through the network.
Control-C to stop the capture.
You can then use Ethereal or WireShark to analyze the capture file.
On the 'Analyze' menu, select 'Expert Info'.
This will look through all the packets and will report
any warning or errors it sees.
It's coming up with a huge number of TCP Bad Checksum errors, a few
Previous Segment Lost and a few Fast retransmission.
Thanks
Matt
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Re: [zfs-discuss] diagnosing read performance problem
Ok on the answers to all my questions. There's nothing that really stands out as being obviously wrong. Just out of interest, what build of OpenSolaris are you using? One thing you could try on the Ethernet capture file, is to set the WireShark 'Time' column like this: View Time Display Format Seconds Since Previous Displayed Packet Then look down the time column for any unusual high time delays between packets. Any unusually high delays during a data transfer phase, may indicate a problem. Another thing you could try is measuring network performance with a utility called 'iperf'. It's not part of Solaris, so you would need to compile it. Download the source from here: http://sourceforge.net/projects/iperf/ I've just compiled the latest version 2.0.4 on snv_93 without problem, using the normal configure, make, make install. If you want to run 'iperf' on a windows box, you can download a '.exe' of an older version here: http://www.noc.ucf.edu/Tools/Iperf/ You can find tutorials on how to use it at these links: http://www.openmaniak.com/iperf.php http://www.enterprisenetworkingplanet.com/netos/article.php/3657236 I've just tried 'iperf' between my OpenSolaris pc an old Windows pc, both with low-cost realtek gigabit cards and linked via a low-cost NetGear switch. I measured a TCP bandwidth of 196 Mbit/sec in one direction and 145 Mbit/sec in the opposite direction. (On OpenSolaris, Iperf was not able to increase the default TCP window size of 48K bytes.) Regards Nigel Smith -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Nigel Smith wrote: Ok on the answers to all my questions. There's nothing that really stands out as being obviously wrong. Just out of interest, what build of OpenSolaris are you using? One thing you could try on the Ethernet capture file, is to set the WireShark 'Time' column like this: View Time Display Format Seconds Since Previous Displayed Packet Then look down the time column for any unusual high time delays between packets. Any unusually high delays during a data transfer phase, may indicate a problem. Along with the errors that I noted previously, some of the packets to seem to be taking a rather long time (0.5s). I've taken a cap file from wireshark in the hope it clears up some information. The capture is less than a minute of playing a video over the cifs share. It's a little too large to send in a mail so I've posted it at http://distfiles.genestate.com/_1_20081027010354.zip Another thing you could try is measuring network performance with a utility called 'iperf'. Thanks for pointing this program out, I've just run it to the gentoo firewall we've got, and it's reporting good speeds for the network. Thanks Matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Nigel Smith wrote: Ok on the answers to all my questions. There's nothing that really stands out as being obviously wrong. Just out of interest, what build of OpenSolaris are you using? Damn forgot to add that, I'm running SXCE snv_97. Thanks Matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Bob Friesenhahn wrote: Other people on this list who experienced the exact same problem ultimately determined that the problem was with the network card. I recall that Intel NICs were the recommended solution. Note that 100MBit is now considered to be a slow link and PCI is also considered to be slow. Thanks for the reply, Yes I understand that 100mbit and pci are a bit outdated, unfortunately I'm still campaigning to have our switches upgraded to gbit or 10gbit. I will see if I can aquire an intel nic to test it with, however before the problem with NICs started it operating fine. It seems though that there is an ongoing problem with NICs on this machine. The onboard ones haven't so much died (they still allow me to use them from the OS) but they just won't start up or accept there is a cable plugged in. The PCI nic does seem to be working and transfers to/from the server seem ok except when there's video being moved. I will do some testing and see if I can come up with a more definite reason to the performance problems. Thanks Matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Sat, 25 Oct 2008, Matt Harrison wrote: The onboard ones haven't so much died (they still allow me to use them from the OS) but they just won't start up or accept there is a cable plugged in. The PCI nic does seem to be working and transfers to/from the server seem ok except when there's video being moved. Hmmm, this may indicate that there is an ethernet cable problem. Use 'netstat -I interface' (where interface is the interface name shown by 'ifconfig -a') to see if the interface error count is increasing. If you are using a smart switch, use the switch admistrative interface and see if the error count is increasing for the attached switch port. Unfortunately your host can only see errors for packets it receives and it may be that errors are occuring for packets it sends. If the ethernet cable is easy to replace, then it may be easiest to simply replace it and use a different switch port to see if the problem just goes away. Bob == Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer,http://www.GraphicsMagick.org/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
On Sat, Oct 25, 2008 at 11:10:42AM -0500, Bob Friesenhahn wrote: Hmmm, this may indicate that there is an ethernet cable problem. Use 'netstat -I interface' (where interface is the interface name shown by 'ifconfig -a') to see if the interface error count is increasing. If you are using a smart switch, use the switch admistrative interface and see if the error count is increasing for the attached switch port. Unfortunately your host can only see errors for packets it receives and it may be that errors are occuring for packets it sends. If the ethernet cable is easy to replace, then it may be easiest to simply replace it and use a different switch port to see if the problem just goes away. Ok, I've just tried 2 other cables, one doesn't even get a link light so it's probably dead. The other one I had suspected was bad and indeed the connection is terrible and the Oerr field in netstat does increase. On the other hand, the Oerr field doesn't increase with the original cable, however the video performance is still bad (although not as bad as with the 2nd replacement cable). I will make up some new cables, and also place an order for an Intell Pro100, as they are supposed to be really reliable. Thanks Matt pgpgGq6AmGFWW.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] diagnosing read performance problem
Hi Matt
What chipset is your PCI network card?
(obviously, it not Intel, but what is it?)
Do you know which driver the card is using?
You say '..The system was fine for a couple of weeks..'.
At that point did you change any software - do any updates or upgrades?
For instance, did you upgrade to a new build of OpenSolaris?
If not, then I would guess it's some sort of hardware problem.
Can you try different cables and a different switch - anything
in the path between client server is suspect.
A mismatch of Ethernet duplex settings can cause problems - are
you sure this is Ok.
To get an idea of how the network is running try this:
On the Solaris box, do an Ethernet capture with 'snoop' to a file.
http://docs.sun.com/app/docs/doc/819-2240/snoop-1m?a=view
# snoop -d {device} -o {filename}
.. then while capturing, try to play your video file through the network.
Control-C to stop the capture.
You can then use Ethereal or WireShark to analyze the capture file.
On the 'Analyze' menu, select 'Expert Info'.
This will look through all the packets and will report
any warning or errors it sees.
Regards
Nigel Smith
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Re: [zfs-discuss] diagnosing read performance problem
On Sat, 25 Oct 2008, Matt Harrison wrote: I've got a lot of video files on a zfs/cifs fileserver running SXCE. A little while ago the dual onboard NICs died and I had to replace them with a PCI 10/100 NIC. The system was fine for a couple of weeks but now the performance when viewing a video file from the cifs share is appauling. Videos stop and jerk with audio distortion. I have tried this from several client machines so I'm pretty certain it lies with the server but I'm unsure of the next step to find out the source of the problem. Other people on this list who experienced the exact same problem ultimately determined that the problem was with the network card. I recall that Intel NICs were the recommended solution. Note that 100MBit is now considered to be a slow link and PCI is also considered to be slow. Bob == Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer,http://www.GraphicsMagick.org/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
