Completely replace SD Card? (duet ethernet)
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For 4Gb and under cards, use FAT16 format. FAT16 provides an additional performance boost over FAT32.
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Good to know. I'll try retesting with the 4GB class 4 card that came with the Duet with FAT16 and 64k clusters. Is that how they are supposed to come formatted? Mine was FAT32 with 32k clusters.
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We have been using FAT32 for the 4GB cards. I was not actually aware of the FAT16 performance increase that David mentioned.
Something to change on the next batch.
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One final data point then.
[c]
Transcend 4gb Class 4 FAT16 with 64kb clusters 00:50
[/c]10 seconds off the FAT32 format.
So there you go. For best speeds the stock card formatted at FAT16 with 64k clusters is the way to go. This might require you to reformat the card yourself though, as out of the box mine was FAT32 and 32k clusters.
If you need a larger card, FAT32 with 64kb clusters and A1 classification.
I may try again with an ideal wireless situation with the router directly line of site to the printer and my laptop on a wired connection, just to isolate the SD card performance. In actual practice there isn't much difference.
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Sorry to be pedantic, would using fAT16 provide a significant upload speed boost?
If I am driving prints remotely (http xfer gcode to Duet, start print remotely, from a script on a server that it will automatically remove completed print files too); Would it provide a useful/noteworthy speed boost to the upload If I reformatted my card to FAT16.
(I'm suggesting not using the whole drive.. eg just force a FAT16 filesystem onto the first four gigs and ignore the rest.. I've done something similar to this before.)
Edit: Looking at the above.. I guess not.
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One final data point then.
[c]
Transcend 4gb Class 4 FAT16 with 64kb clusters 00:50
[/c]10 seconds off the FAT32 format.
So there you go. For best speeds the stock card formatted at FAT16 with 64k clusters is the way to go. This might require you to reformat the card yourself though, as out of the box mine was FAT32 and 32k clusters.
If you need a larger card, FAT32 with 64kb clusters and A1 classification.
I may try again with an ideal wireless situation with the router directly line of site to the printer and my laptop on a wired connection, just to isolate the SD card performance. In actual practice there isn't much difference.
Thanks for running the tests!
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Sorry to be pedantic, would using fAT16 provide a significant upload speed boost?
If I am driving prints remotely (http xfer gcode to Duet, start print remotely, from a script on a server that it will automatically remove completed print files too); Would it provide a useful/noteworthy speed boost to the upload If I reformatted my card to FAT16.
(I'm suggesting not using the whole drive.. eg just force a FAT16 filesystem onto the first four gigs and ignore the rest.. I've done something similar to this before.)
Edit: Looking at the above.. I guess not.
Short stroking a drive like that used to be popular with spinning platters back when they topped out at 120ish gigs, but for an SD card it might actually degrade performance further due to the wear leveling algorithm having less space to work with. If there is some performance to be gained from FAT16 it would probably be lost from that.
As it is, I think unless you have a really poor SD card, you're probably more limited by wireless transfer than write speed.
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The wear levelling algorithm works at a level underneath the FAT format, so it shouldn't be affected.
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I have tried to reproduce this issue, but so far without success. I copied a 384Mbyte file over wifi to the Duet. The speed started at over 1Mbyte/sec but had dropped to 657kbytes/sec by the time it finished. DWC shows file information for it. Then I tacked half a megabyte of useless comments on the end so that DWC would have to search a long way back from the end of the file without finding what it wanted, and uploaded that. Again, no problems but file info is not displayed because the Duet does not search back as far as half a megabyte from the end. When I refresh the file list, it pauses on that file for 4 seconds, but carries on after that.
So I conclude that you can use files up to at least 385Mbytes long if your choice of SD card and format is suitable. This card is a Sandisk 16Gb card with a class 4 speed rating, formatted to FAT32 with 64Kb clusters. In DWC I have the status update interval set to 250ms which I think is the default, and the maximum number of AJAX retries set to 1 which is wrong - I recommend at least 3 when using WiFi.
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Thanks for the feedback, and the testing! super helpful
I'm certainly not going this route for a modest gain, I guess I was optimistically hoping for a dramatic (2x or whatever) speedup
Once this weekend's re-organising and wiring is complete I should have my Pi acting as the AP for my print cupboard, I just, errm, 'acquired' a 10m CAT5 cable for this purpose from the nest at work. This will put the AP ~10cm from the Duet in line-of-sight; so I'm hoping to push the speed if I can, and see if this solves the disconnects that plague me from webcontrol. (yes, I know that may be too close; I'll play with separating them if I see weirdness before complaining here)
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If you are getting disconnects, check that you have the retry count set to at least 3 in DWC.
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20 enough?I've seen all the advice, but since I have a signal strength that flaps between -50 and -70 I'll wait till that is stable before passing judgement.. at the moment I'm happy to continue blaming my end of the network.
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With the signal strength changing that much, I suspect you are getting interference from another device in the same band. Have you tried changing the WiFi channel?
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Just found something odd. I have near identical printers setup, one which has a Duet Wifi, and one which is a Duet Ethernet. Using DWC to upload a 30MB file shows the performance is severely different between the two, but not in a way that I would expect. The Wifi connected Duet can be uploaded to significantly quicker. The Duet Wifi seems to top out at around 580k/sec, whereas the Ethernet only gets to about 340k/s. Could this be a feature of the firmware on the Ethernet version? Does anyone else have similar results?
The SD card in both is a brand new 16GB SanDisk Ultra SDHC Class 10.
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@spoonunit are both SD cards formatted with 64 KB blocks? That can make a difference.
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You can run M39 to check the cluster size.
The other thing that can make a difference is fragmentation of the SD card. A heavily-fragmented SD card tends to slow down the speed of writing to it.
In my tests, both WiFi (with a good signal strength)and Ethernet top out at about 1Mbps if the SD card has a large cluster size and is not heavily fragmented. For very large files it drops to around 800kbytes/sec.
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Will double check. Both were straight out the packet, so I assume they're identically formatted. Assumptions can be wrong though.
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It may be worth checking that the Ethernet physical link has connected at 100Mbps, not 10Mbps.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
Ethernet machine
M39
SD card in slot 0: capacity 15.93Gb, free space 15.89Gb, speed 20.00MBytes/sec, cluster size 32kbWifi Machine
M39
SD card in slot 0: capacity 15.93Gb, free space 15.92Gb, speed 20.00MBytes/sec, cluster size 32kb -
@dc42 Is there M command to check link speed established?
M552
Network is enabled, configured IP address: 0.0.0.0, actual IP address: 192.168.XXX.155Looking at the router, the 100M light is lit. The cable went from duet to cable to a connector on the back of the box. I've plugged the cable in directly to the Duet to rule out that short cable, but the longer cable could in theory still be to blame.
