solid state disk

[Neil.Pate]

Hi All,

I recently have started using a solid-state drive (SSD) in my laptop, and it really flies (Intel X-25).

However, I am quite perturbed about the performance of Diadem 11.1 in loading files off this disk. Loading medium sized TDMS files (300 MB with 20 MB index files) seems to stall, ie the progress bar does not really move for long periods of time.

There is no problem with the disk, random reads and writes are exceptional on this SSD, and have not noticed this slowdown with any other applications. Any idea what is going on here?

Also, to muddy the situation, I am using this on Windows 7. Reading from a USB hard-drive seems to work as normal, so I figure its not the OS.

Any one else notice these kinds of problems?

[AndreasK]

Is it the same file you read from usb stick than you read from the SSD.

One thing is that the file might be fragmented.

But if the index is just about 20 MB this probably not that worse.

Greetings

Andreas

[Brad_Turpin]

Hi nrp,

I would not call a 300 MB TDMS file "medium-sized".  But I would still expect you to be able to load it outright into DIAdem within 15 seconds to perhaps 4 minutes depending on the CPU and RAM of the particular laptop you're on.  What happens when you register-load the TDMS file instead of just dragging it into the Data Portal?  What are the data types of the channels in this TDMS file-- SGLs, DBLs, or scaled I32s or I16s?  Note that DIAdem always loads data as DBLs, so you might be loading more like 600 MB or 1200 MB or even 2400 MB in the worst-case of I8s.

Have you tried to load this TDMS into DIAdem on another computer from a conventional magnetic platter hard drive?  Can you post this 300 MB TDMS file to the ftp.ni.com/incoming site for me to look at?

Brad Turpin
DIAdem Product Support Engineer
National Instruments

[Neil.Pate]

Brad,

I tried using the load menu, it seems to make a bit of difference in that the loading progress bar goes a bit quicker, but it still seems to take its merry time, around 5 to 10 minutes. The hard drive light on my laptop does not even come on for tens of seconds at a time when it is loading the original file, then there is a burst of activity, then nothing again for like 30 seconds etc. Diadem CPU utilisation is very low during all this time and there is nothing else being done on the CPU.

The data is mostly DBLs, about 10 to 15 channels.

Slightly more weird, if I save the dataset once it has loaded (to compact the index file), then the subsequent loads are amazingly quick. I know you are probably thinking its just cached in memory (I have seen this before with a traditional hard disk), but the file loads in about 5 seconds from a cold-boot!

SSDs have very very good random read speeds, so even if the file was highly fragmented it should still be quite quick.

I have a pretty quick laptop (dual core mobile processer) with 4 GB of RAM. I have no problem loading four of these data sets into memory (reloading them after they have been saved), the load goes very quickly and when its done Diadem is happily using 2.5 GB of the RAM and there is no paging to the swap file.

I will never get permission to post the file unfortunately...

Any other ideas?

ps: you are right, 300 MB is more of a baby TDMS file...  about 1 GB is medium sized 😉

Message Edited by nrp on 12-22-2009 09:59 PM

[Brad_Turpin]

Hi nrp,

I actually meant the NAVIGATOR context menu "Register Data", which you get by right-clicking on the TDMS file in the NAVIGATOR tree view.  Since register-loading only loads a description of the data and none of the data points, this really should happen instantaeously.  If it doesn't, then that tells us the problem is in the TDMS index file.

Have you tried deleting the *.tdms_index file and reloading the TDMS file?

If the file is mostly DBLs in 10 or 15 channels, then why would DIAdem be using 2.5 GB after loading the file?  I'd expect no more than 500 MB, and that's a BIG difference.  Something to look into if nothing else works.

Brad Turpin

DIAdem Product Support Engineer
National Instruments