Hey guys.  After learning the RAID lesson the hard way, I'm currently setting up an UNRAID NAS box to store all my stuff.  I really liked what UNRAID claimed and have heard great things about it.  So far, everything is running great with the latest UNRAID Server Pro (4.5-beta6).

 

I've got my box up and running, and plan to eventually have this thing storing all of my media to be accessed by multiple computers.  I'm watching a 1080p mkv video off it right now while posting this, but if I start copying stuff onto the UNRAID box while watching the movie, it stutters and halts and won't play normally unless I cancel the file transfer.

 

File transfer speeds are around 11mb/sec, which is normal for the 10/100 network it's on (soon to be gigabit), but I would imagine it could copy files as fast as possible while maintaining read speed sufficient to play the movie smoothly.

 

I've tried allocating a 250gb drive for cache, but that didn't seem to affect much.

 

I can post system specs / syslog if necessary, but I was wondering if this was expected behavior or a common problem.

 

Thank in advance for everything!

I did some tests before buying the license:

 

http://lime-technology.com/forum/index.php?topic=3025.msg33510#msg33510

 

55mbps Blu-ray stream playing and data copying to the same drive at 10MByte/sec (80mbps):

 

 

But I have a gigabit LAN. If you are copying at 11MByte/sec*, that's 88mbit/sec, which is basically saturating your LAN.

You should expect it to stutter. With a gigabit LAN, you should get better results.

 

 

* Be careful not to confuse B for b. B = bytes, b = bits

Thanks for the quick and informative reply.  I might just try finding a crossover cable and hooking my desktop directly to it just to copy everything over faster, since both mobos have gigabit ethernet ports...

I did some tests before buying the license:

 

http://lime-technology.com/forum/index.php?topic=3025.msg33510#msg33510

 

55mbps Blu-ray stream playing and data copying to the same drive at 10MByte/sec (80mbps):

 

 

But I have a gigabit LAN. If you are copying at 11MByte/sec*, that's 88mbit/sec, which is basically saturating your LAN.

You should expect it to stutter. With a gigabit LAN, you should get better results.

 

 

* Be careful not to confuse B for b. B = bytes, b = bits

 

The 100mbit should be FDX (I'm assuming) so this shouldn't be so much of an issue.

 

If it helps the OP I built a new unraid server at the weekend (latest beta) and noticed the same thing.

 

Whilst writing data to the array directly under parity protection (no cache drive) at around 15-20 megabytes per second streaming even an mp3 from anywhere on the array (not necessarily the same drive!) would cause playback to stutter occasionally.

 

The box was always under full load and was either in kernel space (copying directly to a drive share) or in shfs when copying to a user share.

 

Cpu is a E1400 2GHz dual core celeron. 2 Gig of RAM all interconnected with Gigabit. Copying from the array (whilst not writing) returns a solid gigabit speed transfer rate. Small 3 disk array. 2x 1.5TB Samsung disks (one of which is parity) and 1x 1.5TB seagate for 3 TB total protected.

 

Seagate drive is the latest firmware and has given me no other problems though I'm aware the early ropey firmware drives did 'stutter' as part of their problems.

 

OP - do you have one of the seagate 1.5TB drives in your array anywhere?

 

I think this is a latency issue more than a transfer issue as I also noticed ping spikes to the server during the stutters. Depend on the media player I used and what caching it did also removed the problem. VLC was very sensitive until I gave it a 1 second read buffer after which time mp3 and video playback whilst copying were fine. Windows Media player seemed less affected as did media portal on my HTPC.

 

During the stutter I could hear the drives thrashing (beyond the usual copying 'noise') so I'm not sure if periodically a cache somewhere is being reached and flushed causing a huge dip in disk i/o. Or the seagate is causing a problem.

 

Or this is just normal.

 

I'm not overly worried as I'll be plopping a cache drive in soon (possibly an SSD although I've not decided if that will bring any value yet).

 

I've got it on a gigabit connection now between my desktop and the NAS, and sure enough file copying is going much faster (25MB/second), but the stuttering issue, while not as bad, is still there.

 

Also, I'm noticing the cache drive is not being used at all while copying over.  Does parity need to be enabled for the cache to do anything?  I'm not going to enable it until everything is copied over, then let the NAS build parity from then on.

 

It really just seems like a network priority thing.  Maybe with windows?

I've got it on a gigabit connection now between my desktop and the NAS, and sure enough file copying is going much faster (25MB/second), but the stuttering issue, while not as bad, is still there.

 

Also, I'm noticing the cache drive is not being used at all while copying over.  Does parity need to be enabled for the cache to do anything?  I'm not going to enable it until everything is copied over, then let the NAS build parity from then on.

 

It really just seems like a network priority thing.  Maybe with windows?

 

Ah so you don't have parity enabled at the moment?

 

I think our problems are very different then!

 

N.B. I use llink to stream Blu-rays. Try a http server if you can. Samba and NFS will work most of the time, but when you get to very high bitrates, llink is the way to go.

Also, I'm noticing the cache drive is not being used at all while copying over.  Does parity need to be enabled for the cache to do anything?  I'm not going to enable it until everything is copied over, then let the NAS build parity from then on.

 

Currently, the Cache drive is only used for writes to User Shares on the unRAID server, not for reads, and not for writes directly to the data disks.  It has nothing to do with the parity drive, except that it removes the 'parity penalty' from the writes, if the parity drive is in use.  Without parity, one write to a data disk is one I/O.  With parity, one write is 4 I/O's, which definitely results in some thrashing.  Writes to the Cache drive are always one I/O.