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NAS1200's Slow to copy files

 
Ulrick65
Advisor

NAS1200's Slow to copy files

I have two NAS1200's running server 2003. I have a 1GB lan, with gigabit switch and router. The two NAS devices are connected directly to the gigabit router. When I copy files to the nas devices (or even between them) it starts out fast (50MB/sec+) but then slows down to around 6 to 8MB/sec.

Can anyone help me out with this? What should I be seeing for speeds on these?

Thanks.

Eric
5 REPLIES 5
TTr
Honored Contributor

Re: NAS1200's Slow to copy files

Verify that the 1Gb lan ports are indeed running at 1Gb on both the NAS devices and the switch/router. Sometimes when you connect a server to a switch (or router) there is an auto negotiation between them and they do not link at 1Gb. You may have to either hard set all device lan ports to 1Gb or set one side to 1Gb and the other to auto-negotiate. Also ensure that all ports are set to full duplex.
The 6-8MB/sec looks like a 100BaseT connection. If this is not the problem then you have to look into how the storage is configured within each NAS device.
Ulrick65
Advisor

Re: NAS1200's Slow to copy files

I have checked the links and they operate at 1GB on both ends (also on other PC's I have on the network).

It appears to me to be a drive write issue (perhaps the configuration as you said). I can read from both NAS devices at 65+MB/sec when reading files to another computer on the LAN.

I have the NAS setup at the default configuration. 4-250GB disks. Primary operating system on drive C (mirrored) and secondary operating system on drive E (mirrored). Data partition is drive F and is RAID-5 on all all disks.

Layout (GB sizes are rounded off):

Disk - Drive - Size - Layout

0 - C - 8GB - Mirrored from Disk 1
0 - F - 220GB - Raid5
1 - C - 8GB - Mirrored to Disk 0
1 - F - 220GB - Raid5
2 - E - 8GB - Mirrored from Disk 3
2 - F - 220GB - Raid5
3 - E - 8GB - Mirrored to Disk 2
3 - F - 220GB - Raid5

I was new to NAS servers when I got these a couple years ago, so I am still no expert by any means.

Any suggestions on what I can do differently or if there might be a different thing I can try?

As a side note, it does look like the file transfers fast for almost 50% (I am testing with a 800MB file) then slows down...so I am thinking it fills some buffer then has to wait on the disk write process.

I ran performance monitor, setup to monitor total bandwidth (stays at 1Gb/sec), received Mb/sec (starts out 46MB+, then finishes 6MB to 8MB with avg around 9MB or 10MB), disk read and write percentages (which hover around 175% throughout the transfer which seems odd, how can it be over a 100%?) and disk percent idle (which hovers around 6% to 8%). By the way this is the "Physical Disk" "_Total" instance that I am monitoring.

Any help and pointers would be much appreciated.

Thanks.

Eric
TTr
Honored Contributor

Re: NAS1200's Slow to copy files

There isn't much you can do with the disk layout. It is what it is. The only thing you can choose is NTFS format type and the block size.

The initial burst of 50MB/sec that you get is probably caused by the disk caching effect. Then when the cache empties out, you rely solely on the disk speed. Note you are dealing with SATA disks here and this is an old unit and I can't find any perfromance specs on it.

Elsewhere in this forum there is mention of patches that improve performance, check if any of these apply to you
Ulrick65
Advisor

Re: NAS1200's Slow to copy files

I've not been able to find any discussions about patches for the NAS1200.

Anyone else who has these units ever done any testing on speed? I am curious if it is just me, or is this all these units can do?

Seems to me I read here about people using dual gigabit connections, backups at high speed, etc. But I convinced that the network is not the issue here...it is the write speed of the drives.

I will continue to look for patches, but if you happen to have a link that would be great.

Thanks for the help, I appreciate the feedback.

Eric
Ulrick65
Advisor

Re: NAS1200's Slow to copy files

Here's what I have determined after several hours of testing:

Writing to F: (RAID 5 across all 4 disks) is considerably slower than the writing to E: or C: (both mirrored across 2 disks each). The difference is 75% slower...meaning writing to E: for example is 4 times faster than F:

What I see by running performance monitor is that the system is READING from F: at the same time it is writing. This does not happen on C: or E:...only writing is active.

Is there a reason that the RAID 5 needs to read from the array at the same time it writes? Or is the system reading from F: for some reason whenever anything is written?

I thought maybe DFS was doing it, so I removed it. Then I removed all the shares from F: (except the default F$). nothing makes a difference...it still reads during write operations.

Any thoughts?

Thanks again for the help...

Eric