I was streaming some MP3music  from the tower through Foobar on Windows XP. I then copied a DVD iso to the media server while listening to music from the server. As soon as the transfer of the DVD iso started, the music started stuttering. Dissapointed. I have user shares for all the folders. I thought I would get better performance than that out of my UNRAID.

What performance are you getting.. I don't see you listing it anywhere only a useage scenario.

 

If you can quantify it then it can be compared to se if it an issue

I'm fairly sure that's par-for-the-course with unRAID, running w/o a caching drive. Have you attempted to use it with a cache drive?

 

The way unRAID works, it writes the data to the array, then to the parity drive. During that switch over, it will stutter streamed media. At least it always has for me.

I haven't seen this issue, however, I will do this test to double check it

 

Sometimes it depends on the quality of your parity drive.

On my server, the data drives are 500GB maxtor SATA and the parity drive is a 1TB WD.

 

So we have 7200 RPM data drives, 5400 RPM Parity drives and I don't stutter.

 

Is it because of the platter density of the 1TB drive?

Is it because of the 16MB cache?

It sure ain't the spindle speed!

 

This was one of the reasons I elected to go for a 7200RPM 32MB cache seagate for the parity drive.

 

When ram fills up and the buffer cache is getting flushed, I want it to be handled as quickly as possible.

 

 

I'm fairly sure that's par-for-the-course with unRAID, running w/o a caching drive. Have you attempted to use it with a cache drive?

 

The way unRAID works, it writes the data to the array, then to the parity drive. During that switch over, it will stutter streamed media. At least it always has for me.

Not exactly correct.  The two sets of writes to the two drives are written to disk cache memory interleaved and in parallel.  When the cache fills, a separate process in Linux writes the data to the physical disks to empty it. (This process, "pdflush" is not part of unRaid, but part of the underlying Linux operating system kernel and common regardless of using a RAID protected drive or not.)

 

I frequently rip DVDs while watching other already ripped full bitrate ISO images of my DVDs.  In fact, just to prove it still works, I'm playing a DVD ISO image in my Den, an MP3 from the server in my Bedroom, an avi file on my wireless laptop, and also ripping a DVD from that same laptop to the server.  All are doing fine.

 

In early versions of unRaid, writing took priority over reading...  That was fixed somewhere in version 1.something. 

 

The issue is more often network related.

 

All it takes is one or two dropped packets and then everything seemingly stops for a second or so while the windows networking protocol times out waiting for each packet ack in turn.  To you, it is a stutter.

 

This post describes the issue pretty well.

http://lime-technology.com/forum/index.php?topic=1790.0

 

I'm not saying there could not also be something else going on, but to help futher we would need to see a copy of your syslog to ensure the rest of unRaid on your hardware is working up to speed.

 

Joe L.

Network performance isnt bad when doing 1 thing. Its when I am downloading something from the server and then attempt to upload. It starts choking. All of my drives are Seagate 32MB cache.

 

As I said, lots of possible causes for the poor performance. 

I have an old IDE based unRaid array.  I do have a gigabyte switch and cables rated for gigabyte service.

 

Earlier I was writing 10 gig of data to the array from my digital movie camera on one PC, watching a DVD ISO on a media player, an avi file on a wireless laptop, and playing am mp3 on yet another media player.  All while ripping a DVD ISO image to the server.  Can you have contention, sure, but playing an mp3 is a very light load on the server compared to what I've done at times.

 

You might be only connecting at 100 MB, you might have a disk drive operating in PIO mode, you might have any number of issues to cause poor performance... we just need to get past those that are not an issue to figure out what is going on.

 

The only way for anyone to help you further is for you to post your syslog.

 

Joe L.

Joe, while I agree that the server should be able to handle multiple streams without stuttering, I also believe that copying a DVD ISO and ripping one are slightly different.

 

I also agree that nothing should interfere with streaming a MP3 as the size of an MP3 is small compared to the data stream of an MP3 or DVD ISO

 

Therefore I think doing an actual copy vs a RIP would be a better test.

 

I know with my rips, the data moving to my server is slower then with a copy.

 

 

Another suggestion for better performance, to avoid one of the possible bottlenecks, move your parity drive off the PCI bus.  PCI is fine for normal single disk access, but can become a bottleneck for simultaneous access.  Since every write to the unRAID array involves reading and writing both a data disk and the parity disk, it makes sense for best performance to assign the parity drive to a fast SATA disk on its own unshared PCI Express lane.  The worst case would be an IDE drive on a shared IDE channel on a PCI card.  Disclaimer:  These are just my opinions, informed ones I believe, but personally untested, would be happy to see either verification or correction.

 

Read performance is not usually a problem, whether the drives are slow, all PCI based, all IDE, etc, mostly because the parity drive is not used at all.  As Joe and others have said, you can simultaneously stream multiple media files FROM the server (at low bitrate) without a problem.  Copying a multi-gigabyte file from a fast source TO the server is probably creating an I/O bound condition, hampering all other I/O.

 

For maximum write performance, add a very fast Cache drive, perhaps a Raptor?  Or monitor WeeboTech's testing, to see if a RAID 0 setup can be used for the Cache drive.

 

I've attached my syslog.

 

Here is my setup

 

D-Link 8 port Gigabit switch

Windows XP Machine with Realtek Gigabit onboard card

IBM thinkpad T61Pwith Ubuntu 7.10

Unraid Box (See specs in Sig) - 4 500GB Seagate sata Drive connected directly to onboard sata ports

 

I'm going to do various tests and post the results. You guys can use your judgement as to whether this is normal.

Test Results

 

WinXP Machine

Download 4GB movie from server = 2mins

Download 4GB movie from server while uploading movie to server = 6min 50s

Download 4GB movie from server while Streaming MP3 = No stutter, Movie downloads in 2mins

Stream movie in VLC player + stream MP3 same time = No stuttering at all

Streaming MP3 + Movie streaming in VLC + Download 4GB file to PC = No stuttering

Streaming MP3 + Upload Movie to Server = Stuttering MP3 playback

Streaming MP3 + Streaming Movie + Upload 4GB file to server  = Movie and MP3 stuttering.

Upload of 4GB Movie = 6mins 45s

 

 

 

Joe, while I agree that the server should be able to handle multiple streams without stuttering, I also believe that copying a DVD ISO and ripping one are slightly different.

True, but I was also copying about 10 Gig of data from the hard-drive in my video camera to the server. (via a USB cable.  Granted, it was through my laptop and then over a wireless link, so slower than if a direct connection via a Gigabit lan connection.)

I also agree that nothing should interfere with streaming a MP3 as the size of an MP3 is small compared to the data stream of an MP3 or DVD ISO

 

Therefore I think doing an actual copy vs a RIP would be a better test.

 

I know with my rips, the data moving to my server is slower then with a copy.

It sounds as if the stutters occur when the network is very very busy.  Most of my clients are 100 MB, only 4 machines on the LAN are 1000 MB. I have a feeling my usage is not as heavy as others and I don't saturate the LAN the same way.

 

Joe L.

I'm suffering from the same exact problem... stuttering during MP3 playback while ripping/transferring large files (DVDs) to the Server. Happens in both Winamp(default) and WMP.

 

Main PC:

Corsair 550VX PSU

Abit IP35-E

E6300 @ 3.0Ghz

4x2GB OCZ Reaper HPC (4-4-4-15 variation)

2x 320GB Seagate SATAII drives (7200.10's)

XFX 8800GT

 

UnRaid Media Server:

Antec Earthwatts 430 PSU

MSI K8N Neo3-F

AMD Sempron 2800+

2x512MB 3200DDR

1x1TB Seagate SATAII (7200.11)

1x500GB Western Digital SATAII

1x500GB Maxtor SATAII (7200.10)

 

D-Link DGS-2205 10/100/1000 5-Port Switch (only Media Server and PC hooked up)

with

Linksys WRTP54G Router uplinking for internet access

I'm suffering from the same exact problem... stuttering during MP3 playback while ripping/transferring large files (DVDs) to the Server. Happens in both Winamp(default) and WMP.

 

Your syslog looks good, your performance looks good, I don't see any real problems.  You should not be having any trouble.  Your network did drop out a couple of times for a few seconds each time, around 1:58pm, any chance that was the time of the stutter?

 

The stutter happens continuously while I'm transferring and playing music (it's practically timed intervals... stutter every 5 seconds) so I'm not sure why you'd notice that specifically at 1:58pm. Surprisingly I think video playback is fine (haven't tried HD content yet though)...

So the 'network stutter' at 1:58pm was not the cause.  I'm not aware of any source of unRAID activity peaks with a period of around 5 seconds.  I have not seen reports of such either, but that does not mean there aren't, you may be the first to observe it.

 

I have to lean though to a local source being more likely.  I'm not an expert in these things, but in my experience, the most significant cause of stutter has been local CPU spikes of activity.  Something to test, try playback of an MP3 while heavy transfer to the unRAID server occurs from another computer, not the same one being used for playback.  Either start a rip or transfer from another desktop computer, or start a major copy on the server itself, directly to a parity protected drive, not a Cache drive.  By doing that, you will have isolated your playback machine from local sources of high CPU activity, by moving the heavy activity elsewhere, and the unRAID server will be under as heavy or heavier a load.

 

You can also try monitoring CPU activity on the playback and ripping machine, using Task Manager.  Temporarily setting Update Speed to High will cause even more CPU activity, but will more accurately display the peaks, and who's responsible.

 

I went to transfer an 8gig ISO from my unraid to my laptop and it said it would take 40 minutes. So I tried to transfer the ISO from the server to a windows machine, 40 minutes to transfer. I rebooted unraid box and all machines. Same things 40 minutes to transfer the 8 gig ISO...Something has happened somewhere in the network.

 

I am out of town for work so I will have to wait for a few days until I can do some testing.

 

Anyone experience this?