WHS Performance

[mtber]

Local IOZone Tests

yep, I probably have Cool & Quite enabled. Will have to check into it.


ok, ran the local IOZone tests on all of my systems last night. Results are attached. The first is a plot of Read results, the 2nd is Write results and the third is a summary of the machines and the full IOZone results for each.

What do they suggest?

Are the horrendous write results for the two IDE drives (John & Dorene) representative for IDE or is soemthing else up? (I had forgotten that an IDE was in the Dorene system, I guess that I need to upgrade her? John is an aging Dell Inspiron 9300 notebook, he will not be getting any upgrades.)

Thanks,

John

 

[Jay_S]

Now we're getting somewhere!

I'm pretty sure these IOZone tests measure sequential reads and writes. So, similar to a single large file being written/read. Results will be quite different for multiple smaller files.

Your WHS looks plenty fast: 100MB/s reads & writes.

Let's focus on Eric, as your fastest client (ignoring kelsey's eSata drive for the moment). The 4 & 8GB results suggest that Eric's HDD is physically only capable of: 51-52 MB/s reads and 45-50 MB/s writes. That's pretty poor by today's standards, as demonstrated by WHS's Seagate 7200.12 results.

If you're transferring a file from Eric to WHS, Eric's 51-52 MB/s read speed is your bottleneck. Factoring in network and application protocol overhead, the 50MB/s you reported here sounds pretty good, actually!

What do you see transferring to/from Kelsey's eSata drive to WHS? Kelsey is running Vista (SP1? check on that, as SP1 improved the file copy engine), and the eSata HDD is capable of 80MB/s reads - so I'd expect transfers from Kelsey's eSata drive to WHS to be better then Eric.

 

[wathman]

You had a question about how windows 7 performance stacks up, and since I've been able to do a little real world testing with the final version of Win 7 Ultimate 64-bit, (Was lucky enough to be a Win 7 Launch Party Host) My fastest transfers are between my core i7 860 (with the win 7 install) as client, and a C2D E6850 running Vista Ultimate 64-bit. Anything going between those two machines transfers at speeds between 100-107 MB/sec. Both machines are using RAID 0 arrays so I have a disk performance advantage on my server, but eventually I will migrate it to a RAID 5 array when I can invest a bit more in extra drives.

Basically, it should be about the same as Vista SP 2 performance, maybe a bit better on hardware limited systems as it is supposed to be more friendly with resource usage under win 7.

 

[mtber]

So the Eric system is performing pretty much as good as it will get with the current hard drive? Wow, there is a huge difference between the single 1 GB file transfer versus the 351 files totally 1GB (the latter being more typical usage for my systems right now) – 50 versus mid 20’s MB/S.

Kelsey is running Vista 64 - 6.0.6002 Service Pack 2 Build 6002

I don't have manual transfer data between Kelsey's eSata and WHS, I'll generate that tonight.

However, a massive copy (couple hundred gigs of thousands of 2-8 MB digital pics) from WHS to Kelsey's eSata is what got me concerned to begin with. That transfer started off fast (in the area of 80 MB/S), but within a minute or so dropped off to around 3 MB/S and took all night long. But,

• That was with a different 500 GB eSATA drive, a Seagate Barracuda 7200.10 ST3500630AS versus the WDC WD5001AALS-00L3B Caviar black on there now (I have two external 500 GB eSata drives that I back up all of the family photos, etc to and always keep one at work in case the house burns down or something)
• The Barracuda 7200.10 is older and not in the same league as the Caviar Black
• I realize that is a much different copy than my little 1GB 351 file test set.

Here is the manual file copy data (MB/S) that I do have for Kelsey.

Kelsey (Vista 64) to WHS - 21
WHS to Kelsey (Vista 64) – 26

Kelsey (Vista 64) to Eric (Vista 32) – 37

Kelsey (Vista 64) to Kelsey (Vista 64) eSATA Drive - 83

John (XP) to Kelsey (Vista 64) – 9
John (XP) to Kelsey (Vista 64) – via cross over cable – 13

So, to round out the data set, I need to generate the large manual single file copy data to compare to the IOZone Local Test data I just generated.

Another question: The performance that I’m most concerned about is accessing digital photos stored on the WHS for reviewing and editing by either PhotoShop Elements (all catalogs, etc stored on WHS) or Lightroom (catalog local, images on WHS). Is the file read/write performance a reasonable surrogate for telling if the particular system is performing as well as it can with it’s hardware/OS (and maybe identifying what could be upgraded to improve performance)?

Thanks,

John

 

[mtber]

Nevermind that last question. On reflection, it's primarily the read performance off of the WHS that's going to impact performance when moving through a Photoshop Elements Catalog and pulling up a file to edit. Same for Lightroom, with a little more emphasis on the local machine since the catalog and thumbnails are local.

I think.

 

[mtber]

wathman, thanks for the Win 7 feedback.

Here's the manual Win Explorer copy data for Kelsey eSata (WDC WD5001AALS-00L3B Caviar black ) and the WHS


Single 1 GB file

Kelsey (Vista 64) eSATA to WHS 56 MB/S - maintained speed throughout copy
WHS to Kelsey (Vista 64) eSATA 30 MB/S - initiated from Kelsey - started >60 MB/s, finished ~30 MB/sec
​

1 GB folder of 351 files

Kelsey (Vista 64) eSATA to WHS 28 MB/S - steady speed throughout copy
WHS to Kelsey (Vista 64) eSATA 14 MB/S - steady speed throughout copy
​

 

[wathman]

seems like you're getting better performance numbers, but I think your older hard drive is doing more harm than good since it's contribution of virtual memory to the system is not exactly speedy. Since that system has 4GB of system RAM, it might be interesting to see what your transfer speeds do if you turn off virtual memory.

Also, I noticed that you are using different brands of DDR2 RAM, this in itself is not a problem, though I'm guessing one set may be better than the other set. In cases like that, the motherboard should automatically clock all your RAM to the slower of the two, but it may have done something strange. Might be worth at least verifying your RAM timings are set correctly on Kelsey.

 

[benogil]

This is a a response from another forum, with a parallel scenario. May be worth a try.
I've had similar problems with my WHS / W7 RTM setup and these seem to have helped, though I'm still early in testing.

http://support.microsoft.com/kb/948066

Try disabling this feature by changing the following registry setting to 0xffffffff (DWORD):
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\NetworkThrottling Index

You can also change
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\SystemResponsiven ess
to 10 from 20.

You will need to reboot after making this change.

Other things to try (though it looks like you've adjusted adapter settings):
Network loss due to the PC network card:
- Right click on My Network Places and choose properties.
- Double click on the Local Area Connection icon to bring up the status page.
- Check that the Speed is reported as 100Mbps or 1Gbps.
- Click Properties. Check the brand/model of the network interface:
-- nForce based interface: Click Configure and switch to the Advanced tab. Disable checksum offloading features.
-- Intel based interface: Click Configure and switch to the Advanced tab. Test with alternative Interrupt Mitigation settings. onfigure are switch to the Advanced tab. Increase the Receive Buffer size (if this option is present). Test with the Interrupt Mitigation/Moderation setting both On and Off (if this option is present).

Ben

 

[00Roush]

wathman, thanks for the Win 7 feedback.

Here's the manual Win Explorer copy data for Kelsey eSata (WDC WD5001AALS-00L3B Caviar black ) and the WHS


Single 1 GB file

Kelsey (Vista 64) eSATA to WHS 56 MB/S - maintained speed throughout copy
WHS to Kelsey (Vista 64) eSATA 30 MB/S - initiated from Kelsey - started >60 MB/s, finished ~30 MB/sec
​

1 GB folder of 351 files

Kelsey (Vista 64) eSATA to WHS 28 MB/S - steady speed throughout copy
WHS to Kelsey (Vista 64) eSATA 14 MB/S - steady speed throughout copy
​

Hmmm... Was hoping to see a bit higher than that. Any chance you could move that eSATA drive over to the Eric system and run the same test? Better yet any chance you could move the drive from being in the eSATA enclosure to an internal drive? Technically eSATA should be just as fast but I am not quiet sure if that is ACTUALLY true when dealing with moving data across the network. I have never owned a eSATA enclosure so I am not sure if it makes a difference. Just trying to eliminate any possible bottlenecks.

You know since seeing how low your performance is I am considering testing WHS with Vista SP2 on my server and main PC. I have extra IDE drives I could use for the server to test with. Also I have been meaning to reinstall Vista. It has been so long since I set it up I don't recall what problems I had with it right out of the box. Haven't tested SP2 yet either.

00Roush

 

[00Roush]

This is a a response from another forum, with a parallel scenario. May be worth a try.
I've had similar problems with my WHS / W7 RTM setup and these seem to have helped, though I'm still early in testing.

http://support.microsoft.com/kb/948066

Try disabling this feature by changing the following registry setting to 0xffffffff (DWORD):
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\NetworkThrottling Index

You can also change
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\SystemResponsiven ess
to 10 from 20.

You will need to reboot after making this change.

Other things to try (though it looks like you've adjusted adapter settings):
Network loss due to the PC network card:
- Right click on My Network Places and choose properties.
- Double click on the Local Area Connection icon to bring up the status page.
- Check that the Speed is reported as 100Mbps or 1Gbps.
- Click Properties. Check the brand/model of the network interface:
-- nForce based interface: Click Configure and switch to the Advanced tab. Disable checksum offloading features.
-- Intel based interface: Click Configure and switch to the Advanced tab. Test with alternative Interrupt Mitigation settings. onfigure are switch to the Advanced tab. Increase the Receive Buffer size (if this option is present). Test with the Interrupt Mitigation/Moderation setting both On and Off (if this option is present).

Ben

Just wanted to bring up a couple of points. First would be that normally these changes would only affect network performance while any type of media is being played. There was a thread a while back about this. Next would be that HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\SystemResponsiveness registry key sets the amount of CPU resources set aside for non media tasks. Default is 20%. This means that when media is being played all other tasks combined are limited to 20% cpu usage. So I believe this should be made bigger not smaller to allow other non media tasks more cpu usage. I currently have mine set at 50.

00Roush

 

[mtber]

00Roush

yep, I should be able to move the eSata to Eric and run the tests, will take me a through the end of the weekend to get a chance top do it.

I'm wishing that I had started looking at all of this stuff and established benchmarks before putting that older 160 GB in Kelsey. (I do have Passmark benchmarks on all systems before, haven't run them since putting the 160 in Kelsey. Are they of any value? - I'm assuming the IOZone and manual file copy data is "better".

Boy, I didn't realize that my HD's were so below par. Seems that just a couple of years ago, if you had a 7200 rpm drive I was happy. - although I guess the same would be said of the other major components.

I have ordered a Seagate Barracuda 7200.12 ST3500418AS 500GB to put in Dorene for my planned Win 7 upgrade. I don't need 500 GB in that machine now that I have the WHS, but it seems that it's not really significantly cheaper to go with less capacity from a price/performance perspective.

wathman,

I'll check the RAM timings and experiment with the virtual memory when I get a chance.


Ben,

The network speed is reported as 1 GB.

The network interface driver fields and settings on Kelsey are below. There are several CheckSum entries, would I disable them all? What about the Large Send Offload? (I see that I haven't disabled the IPv6 on this system either.)

Marvell PHY
Driver Date - 5/3/2007
Driver version - 65.7.4.0 - Nvidia Driver
Vlan ID - 1
Interupt moderation - Enabled
IP CheckSum Offload - Rx&Tx enabled
TCP Checksum offload (IPv4) - Rx&Tx enabled
TCP Checksum offload (IPv6) - Rx&Tx enabled
UDP Checksum offload (IPv4) - Rx&Tx enabled
UDP Checksum offload (IPv6) - Rx&Tx enabled
Flow Control - Rx&Tx enabled
Jumbo Frame - 1514 bytes (no options to disable, just chnage size)
Large Send Offload (IPv4) - Enabled
Large Send Offload v2 (IPv4) - Enabled
Large Send Offload v2 (IPv6) - Enabled
Priority & Vlan - Priority Enabled
Receive side scaling - Enabled
Transmit buffers - Enabled
Low Power State Link Speed - Enabled
Network Address - not present
Speed & Duplex - auto negotiation
Wake on LAn Capabilities - Enabled



Thanks,

John

 

[Jay_S]

I'm wishing that I had started looking at all of this stuff and established benchmarks before putting that older 160 GB in Kelsey. (I do have Passmark benchmarks on all systems before, haven't run them since putting the 160 in Kelsey. Are they of any value? - I'm assuming the IOZone and manual file copy data is "better".

Not better really, but probably not objectively comparable. In my experience, IOZone is ruthless in ways the other HDD benchmarks aren't.

Boy, I didn't realize that my HD's were so below par. Seems that just a couple of years ago, if you had a 7200 rpm drive I was happy. - although I guess the same would be said of the other major components.

I hear ya - this was a hard lesson for me as well. A 7200rpm drive is going to give you latency performance you can't get with slower rpm drives. But throughput depends on rpm + platter density (GB / platter). My 7200.9 was a spare I had from an old build. It replaced a failing 7200.11 in my htpc. The upside is that it's still under warranty! Since I rip directly to (and play from) my server, the slow HDD isn't a big deal.

I have ordered a Seagate Barracuda 7200.12 ST3500418AS 500GB to put in Dorene for my planned Win 7 upgrade. I don't need 500 GB in that machine now that I have the WHS, but it seems that it's not really significantly cheaper to go with less capacity from a price/performance perspective.

The 500GB 7200.12 is the one you want - all 500GB is on a single platter. High platter density is good for throughput, and with only 1 platter power consumption is low.

Having praised the 7200.12, magnetic storage is a dead end. Especially in your/my environment (desktop clients with mass available networked storage). SSDs are the future. They're expensive now (and NAND prices are crazy volatile), but no storage tech has had such a disruptive effect in a long time. Slow magnetic storage has been "good enough" for ... well, as long as magnetic storage has been around. Today you can get better performance than 2-drive RAID0 with a single SSD, with 10x the random I/O, 1/10th the power consumption, 1/100 the seek time, zero noise - in a smaller form factor to boot! I can't wait for SSD's to drop in price. Fingers are crossed for some Intel or Indilinx love around black friday.

 

[mtber]

The SSDs do look fantastic for this type of application - when the prices become reasonable. Thinking about that, I don't feel too bad about "wasting” the unneeded capacity of the 7200.12 500 GB drive. Once the SSDs come down to reasonable prices, I can put one in Dorene and move the fast 500 GB to expand the WHS storage – win/win.

The 7200.12 500 GB seems to be a sweat spot right now and hard to pass up at $55 with free shipping. A couple of months ago a comparable drive would have been $100.

Here’s the Passmark Performance test comparison for Kelsey (kind of hard to read the jpeg). The 28-Aug data was with a Seagate Barracuda 7200.10 ST3500630AS 500GB, Disk Mark 329 (slower than the 384 reported in Passmark's tables). The “This Computer” is the Seagate Barracuda 7200.9 ST3160812AS7200160GB, Disk Mark 409. Looks like she is actually marginally better off than when I had the 500’s in there. But, slow is slow.

 

[mtber]

duh, no eSata port on Eric, so won't be able to easily make that comparison.

 

[00Roush]

duh, no eSata port on Eric, so won't be able to easily make that comparison.

LOL! That's okay.

I have actually been doing some testing with WHS and Vista SP2. So far it has been interesting. I also now have a eSATA enclosure and a couple more 320 GB WD Carviar Blue drives to play with. Read speeds were seemed to be good but write speeds had some problems. I think I found out what my problem is so I am going to reload WHS and Vista to see where I am at. On a side note... From what I can tell the eSATA drive works just as fast as a internal drive. I will post up some of my results after some more testing.

During my testing I have come across quite a bit of information talking about problems with Windows Server 2003 SP2 network offloading features. WHS is based on this verison of Windows so the same problems could be in WHS. Not sure if you want to try it but these changes might help.

To manually disable RSS and TCP Offload yourself, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
3. Right-click EnableTCPChimney, and then click Modify.
4. In the Value data box, type 0, and then click OK.
5. Right-click EnableRSS, and then click Modify.
6. In the Value data box, type 0, and then click OK.
7. Right-click EnableTCPA, and then click Modify.
8. In the Value data box, type 0, and then click OK.
9. Exit Registry Editor, and then restart the computer.

This is straight out of this Microsoft KB.

You know I just realized a couple of things...

First was that I have not seen any file transfer tests between Eric and Kelsey's eSATA drive using a large single file.

Next would be that it might be helpful to see Iperf results between some of your other machines. Maybe do a Eric\Kelsey or Eric\Dorene test.

Last was when you ran the Iozone tests on your WHS drive you were using the C drive I assume. This means you were only testing the Seagate 7200.12 drive. My understanding is that WHS writes to the other disks before it writes to the drive that has the OS on it. This means that most likely the other two drives are actually the ones that need to be tested. The problem is that with WHS the storage setup is well... goofy. By default the data drives are not assigned a drive letter so testing them becomes a little more difficult. I think you can assign a drive letter with the computer management control panel but I am not sure if that works out. I will test this out and see if it works.

I hope we are not driving you nuts with all of this. By the way your presentation of your results has been excellent. Everything is well organized and easy to read/understand. Especially considering how much data has been collected in this thread.

00Roush

 

[00Roush]

Okay I have done a bit more testing. First up I was able to run Iozone tests on my data drive in WHS. It turns out that WHS does not assign drive letters to data drives but instead maps them to folders. For example my data drive was mapped to c:\fs\4. I found this by going to Control Panel\Administrative Tools\Computer Management then double clicking on Disk Management near the bottom.

On my system I had the following listed:
( E: ) (This was a USB flash drive)
DATA (This was my data drive)
DATA ( D: ) (This was the 2nd partition on the system disk that was created by WHS which is also used for data)
SYS ( C: ) (This was the 20 GB system partition created by WHS)

Once here I right clicked on the drive marked "DATA" that did not have a drive letter attached and selected "Change Drive Letter and Paths...". A box popped up that showed where the drive was currently mounted. Then I just used that path with Iozone.

iozone -Rab c:\iozone\results.xls -i 0 -i 1 -+u -f c:\fs\4\test.txt -y 64k -q 64k -n 256m -g 8G -z

Both read and write speeds were between 104000 and 95000 from 2 GB to 8 GB file sizes with this drive.

File copy speeds were between 90 and 100 MB/sec for a few test files ranging in size from 1.2 GB to 20.1 GB in size. I have the exact copy times and file sizes if you want them. The problem I mentioned with write speed was caused by a storage controller driver. I found the standard windows version works best for my setup.

Here is my setup:
Client:
Athlon 64 5400+ (2.8 Ghz) CPU
2 x 2GB DDR2 800 RAM
Asus M3A78-T Motherboard
Marvell Yukon 88E8056 PCI-E Gigabit Ethernet Onboard Motherboard
320 GB WD Caviar SE16 Hard Drive (OS drive)
320 GB WD Caviar Blue Hard Drive in a eSATA enclosure (Data drive)
Vista SP2 x64 with all the updates

Server
Opteron 165 (1.8 Ghz) CPU
2 x 1GB DDR 400 RAM
Asus A8R32-MVP Deluxe Motherboard
Marvell Yukon 88E8053 PCI-E Gigabit Ethernet Onboard Motherboard
320 GB WD Caviar Blue Hard Drive (20 GB partition for OS)
320 GB WD Caviar SE16 Hard Drive (Data drive)
WHS SP2 trial with all the updates
Server

My setup would most likely be considered a best case scenario. Everything was freshly installed and no other programs were installed.

00Roush

 

[mtber]

00Roush,

Here’s some IOZone testing results between Kelsey (Vista 64) eSata, Eric (Vista 32), and Dorene which has been newly configured with a 500 GB Seagate 7200.12 and is now running 64 bit Win 7 (quite an upgrade compared to the XP/5400 rpm IDE).

Wait, that can't be right - I couldn't have run "from" Kelsey eSata, I was just running from regular Kelsey, duh.

I need to re-run the Eric to Kelsey eSata as the 8 GB point looks spurious.

In re-reading your post I see that you asked for IPerf between machines, do these IOZone results achieve the same end?

The bold lines are “local” IOZone runs.

I gathered data on manual file transfers between Eric and Kelsey eSATA, but need to repeat them as there are some inconsistencies.

I’ve also attached a summary of my manual file copy tests to date.

Nope, not driving me nuts (the computers may be driving me nuts) I haven’t had time to keep up with all of the suggestions, but do appreciate the help.

All IOZone and manual copy tests to WHS were done by copies to the Public folder, in the case of IOZone by mapping that share to a drive letter. Maybe it would be worthwhile for me to map that public folder through remote desktop on the WHS and re-run the IOZone local test to that mapped drive.


John

 

[mtber]

I checked, and the settings below were already set on my WHS.

To manually disable RSS and TCP Offload yourself, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\Tcpip\Parameters
3. Right-click EnableTCPChimney, and then click Modify.
4. In the Value data box, type 0, and then click OK.
5. Right-click EnableRSS, and then click Modify.
6. In the Value data box, type 0, and then click OK.
7. Right-click EnableTCPA, and then click Modify.
8. In the Value data box, type 0, and then click OK.
9. Exit Registry Editor, and then restart the computer.

​

 

[mtber]

00Roush,

I did some testing to follow-up on your WHS testing in regard to which disks are actually being written to.

Attached is a plot of local tests results run through Remote Desktop. I ran the same IOZone test on the C: and D: drives and then mapped the Public folder to a drive letter and ran the same test.

The Read data seems pretty clear, both the Public and D: data are really slow compared to the C: data. The Write data are less clear with D: being slow and Public being better, but not at straight C: performance.

I’m not sure what to make of the data other than to confirm your point that the WHS isn’t using my fast Seagate 7200.12 for client I/O operations. That is a real BUMMER!

This is very discouraging and suggests that it’s crippling to move “older” slower drives to the WHS storage pool to allow folder duplication. That’s part of the whole point of setting up the WHS, who wants to have to buy all new drives to expand storage when you have multiple otherwise decent 500 GB SATA drives laying around.

This data also would seem to change the equation for all of the other IOZone data that I have been generating for client to WHS. I’ll need to take some time to sift through it and see if it is consistent and makes sense.

A question though, since I’m typically working with much smaller files, < 10 MB, does any of this 2- 8 GB IOZone data really matter except when I just occasionally do big file copies? I understand that it’s needed diagnostically to determine if I have any configuration issues that are affecting overall performance. I’m just wondering if I’m chasing my tail at this point.

Thanks,

John

 

[00Roush]

Well I am not sure if I was clear in the previous post about the drives to test. With WHS testing D: or your public folder does not actually mean you would be testing your data drives specifically. D: is actually the second partition on your Seagate 7200.12 drive but it could also be a combination of all three drives. Same goes for your Public folder... it is a single folder that is linked to all three drives. This could also mean that if you have file duplication on it could have affected your Iozone results. I am not sure exactly though as the way WHS deals with the storage pool is unusual. This is why I recommended using the Disk Management part of the Computer Management control panel to find out where (what folder) WHS mapped your data drives. That way you can test them directly without interference from the drive extender software. But file duplication still might be in effect. With that said your results still might be correct. I mean testing the Public folder should give you actual read\write speeds to\from that folder. If that is true then you have definitely found a bottleneck.

Now you are hitting on some points that really irk me with WHS. Like the fact that you have no control over where your data gets written. Also the fact that by default WHS installs itself on the largest drive (fastest in your case) in the system. Then this drive is set to be used the least amount. This means if you want to use a old small drive as the OS drive you have to only have that drive hooked up when installing WHS. Also using this drive could bring down your overall performance as it might be considerably slower than some of the other drives in the storage pool. Basically what it comes down to is if you want consistent high performance out of WHS all of your drives should have similar read\write speeds. At least from what I can tell.

You do make a good point about the different file sizes. Testing the larger file sizes allows us to see performance without interference from files being cached. In reality this is what would happen if you tried to open a 10 MB file that had not recently been opened. It would have to be read directly from the disk and not memory so we want to see the actual speed data can be read from the disk. A single large file also helps with consistent resuslts. As you mentioned it is used as a diagnostic tool to determine if you have any configuration issues that are affecting overall performance.

Here is my thought process... I test for the best case scenario getting rid of all variables that might interfere with performance. This is helpful because I know from here performance goes down. So using Iperf I test the best case for network throughput. Then using Iozone I can test the best case local disk throughput. These results can give me a good idea of what I can expect for best case performance for network file transfers. The higher these results the better the chance that every other scenario will also have higher performance. For example... my best case scenario for large file transfers is 50 MB/sec. (Iperf of > 900 Mbps and Iozone of ~55 MB/sec read write) Now for a scenario of transfering 100 files at 10 MB a piece. Actual tranfser speed comes in at about 40 MB/sec or about 80% of the maximum. Now lets say the my best case scenario for a large file is 100 MB/sec. There is a chance that I still might see around 80% of maximum transfer speed so about 80 MB/sec. Realistically it would probably be more around 60-70 MB/sec though.

In your case it really comes down to what works for you. If photos seem to open quickly and you are able to move files around without much wait I'd say you doing good.

00Roush