SMB transfers are stop and go

[Marc Schubert]

Hi,

 

I'm using Alt-F 0.1RC3 on a DNS-323 and I'm experiencing "stop and go" SMB transfers.

 

I'm transferring videos (AVI, 700MB+) from a Windows 7 Pro workstation over a gigabit network to the box. Windows file transfer status typically shows a transfer speed of around 10MB/second (is this normal?)...

 

What concerns me is that when I look at the Windows Task Manager - Networking tab, it shows the transfer going (around 10% Network Utilization) for 5-10 seconds and then it drops to 0% (and the DNS-323 HDD lights stop blinking), for about 3-6 seconds, and then it starts transferring again, and it does this over and over. Is this normal?

 

As well, when I went to the Alt-F status page during the transfer, it showed the CPU at 100% utilization. Is this normal?

 

Thank you.

[João Cardoso]

On Thursday, August 29, 2013 3:55:59 AM UTC+1, Marc Schubert wrote:

Hi,

 

I'm using Alt-F 0.1RC3 on a DNS-323 and I'm experiencing "stop and go" SMB transfers.

 

I'm transferring videos (AVI, 700MB+) from a Windows 7 Pro workstation over a gigabit network to the box. Windows file transfer status typically shows a transfer speed of around 10MB/second (is this normal?)...

Yes.

 

 

What concerns me is that when I look at the Windows Task Manager - Networking tab, it shows the transfer going (around 10% Network Utilization) for 5-10 seconds and then it drops to 0% (and the DNS-323 HDD lights stop blinking),

so it stop receiving data...

 

for about 3-6 seconds, and then it starts transferring again, and it does this over and over. Is this normal?

No, you should see an almost continuous throughput. Try rebooting each box at a time (start restarting the MS box)

 

As well, when I went to the Alt-F status page during the transfer, it showed the CPU at 100% utilization. Is this normal?

Yes,  it has a very low-powered CPU and memory

 

Thank you.

[Marc Schubert]

Thank you for the reply.

I'll try rebooting later and let you know how it goes.

[Marc Schubert]

UPDATE:

I rebooted my Windows 7 workstation -> no change

I then rebooted the NAS and then the Windows 7 workstation again -> no change

However, I noticed that downloads from the NAS to my Win 7 workstation are perfect. Task Manager shows a (nearly) steady/continuous transfer at around 14Mbps.

I updated my Windows 7 workstation NIC driver and modified some of the NIC settings for performance. I've noticed that uploads to the box are now a little slower (~8.5Mbps) and the transfer pausing seems to be more frequent.

Is it possible that my Win 7 workstation is overwhelming the NAS and the NAS needs to pause to flush it's buffers or something? I've checked the NAS logs and don't see anything suspicious...

P.S. I noticed that when downloading files from the NAS, only the right hard drive LED flashes. Shouldn't both right and left LED's flash??

Thank you.

[João Cardoso]

On Wednesday, September 4, 2013 9:42:24 PM UTC+1, Marc Schubert wrote:

UPDATE:

I rebooted my Windows 7 workstation -> no change

I then rebooted the NAS and then the Windows 7 workstation again -> no change

However, I noticed that downloads from the NAS to my Win 7 workstation are perfect. Task Manager shows a (nearly) steady/continuous transfer at around 14Mbps.

I updated my Windows 7 workstation NIC driver and modified some of the NIC settings for performance. I've noticed that uploads to the box are now a little slower (~8.5Mbps) and the transfer pausing seems to be more frequent.

Is it possible that my Win 7 workstation is overwhelming the NAS and the NAS needs to pause to flush it's buffers or something?

In theory no.

There is a mechanism called "congestion control algorithm" where the slower box send a "Hold-on" to the faster sender, until the right (transfer window) value for both is found.

You also said that when the transfer pauses "the DNS-323 HDD lights stop blinking", so it is not doing anything (the congestion algorithm works at the millisecond, it should not be visible in the transfer plot).

Does the network leds blink during the 3-6 sec pause?

 

I've checked the NAS logs and don't see anything suspicious...

P.S. I noticed that when downloading files from the NAS, only the right hard drive LED flashes. Shouldn't both right and left LED's flash??

Do you have RAID0/1? I observed that on RAID1 the drives leds alternate at a slow pace. I would expect simultaneous (or faster alternation) access, but it's out of my control (or knowledge)

 

I don't have any clues for you... but continue power-cycling switches/routers... are you on a busy network? IPTV? streaming? try to isolate the NAS and Win7 computer...

What does other users with win7 have to say? No issue?

[Marc Schubert]

Thank you for the ideas.

 

Don't know if you're talking about "Flow Control". I do know that Flow Control is disabled on everything (NAS, switch, and pc)

 

The HDD LEDs stop blinking (go solid blue) during the pause, they resume blinking after the pause until the next pause or when the transfer is finished.

 

The network LED on the NAS stays solid all the time. The network LEDs on my switch and PC blink a lot LESS during a pause.

 

The NAS is setup in RAID 1 with two identical hard drives (1TB). After further testing I found that the HDD LED's do alternate (right will blink for a while and then left and then right...) when downloading a large file from the NAS.

 

It is not a busy network, only a couple computers and a printer. Traffic is mainly web browsing, email and SMB transfers to NAS. I'll try setting up shares on another computer and see if the same transfer issues occur.

 

NOTE: I recently did a few uploads that did not have the stop and go (pausing) issue. So right now it seems to be random as to whether there'll be issues. I've attached a screenshot of my task manager showing one upload that had no issues, and then a second upload plagued by the "pausing" issue.

 

I have a theory that this may be related to the filesystem (EXT4).... As I stopped seeing the issue in random uploads after I had uploaded a bunch of large files and deleted them. Is it possible that these issues occur when writing to "clean" or "unwritten" clusters on the NAS??

 

Thanks again for all the support!