S9 Autoset SD Card Capacity?
- Slartybartfast
- Posts: 1633
- Joined: Wed Sep 01, 2010 12:34 pm
S9 Autoset SD Card Capacity?
I just finished saving my data from the last week, and just for grins, looked at the capacity of my SD card. I've been using it since September, and figured it is probably getting close to full. So I provoked the Properties thingy on XP and,
What to my wondering eyes should appear,
But the following image which I thought was quite queer:
Seems there's only a very small amount of data stored on this 1 Gig card, leaving beaucoup room for more than the 7 days of detailed data that the S9 stores. So why the need for such capacity if the S9 only utilizes a very small part of it?
I don't know why that bothers me, but it does.
What to my wondering eyes should appear,
But the following image which I thought was quite queer:
Seems there's only a very small amount of data stored on this 1 Gig card, leaving beaucoup room for more than the 7 days of detailed data that the S9 stores. So why the need for such capacity if the S9 only utilizes a very small part of it?
I don't know why that bothers me, but it does.
Last edited by Slartybartfast on Fri Jun 24, 2011 2:51 pm, edited 1 time in total.
Re: S9 Autoset SC Card Capacity?
Could it be because you can leave your SD card in the machine for 30-days to record a month's worth of detailed data, before HAVING to remove it otherwise the new data will save over the oldest data?
Cheers,
xena
Cheers,
xena
_________________
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Additional Comments: Dx 10/14/10. Also a T2 diabetic. High night/fasting numbers prompted a sleep study and here I am :-) |
- Slartybartfast
- Posts: 1633
- Joined: Wed Sep 01, 2010 12:34 pm
Re: S9 Autoset SC Card Capacity?
I left it in for 2 weeks this time, and it only recorded 7 days of detailed data as it always does. Perhaps there's a setting that I haven't found yet?
Re: S9 Autoset SC Card Capacity?
Slartybartfast wrote:I left it in for 2 weeks this time, and it only recorded 7 days of detailed data as it always does. Perhaps there's a setting that I haven't found yet?
Re: S9 Autoset SC Card Capacity?
Hi Slarty and all, to me the question is more like, since there is so much more room on the card, why doesn't the S9 make more use of that space? The S9 Autoset II Clinician Manual pg 23 has a chart that shows it writes 365 nights of summary data to both the S9 and SD card. It writes 30 nights of detailed data to the SD card only. It writes 7 nights of high resolution flow data to the SD card only.
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Last edited by Jeffster on Mon Jun 20, 2011 2:03 pm, edited 1 time in total.
- Lizistired
- Posts: 2835
- Joined: Tue Dec 14, 2010 10:47 pm
- Location: Indiana
Re: S9 Autoset SC Card Capacity?
I tend to agree with Jeffster. Store more high rate data. It's probably used because it's a standard storage format. It's hard to find a 1 gig anymore.
How long do you think it will take to fill it up?
How long do you think it will take to fill it up?
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Machines Video: http://www.cpaplibrary.com/machine-education
- Slartybartfast
- Posts: 1633
- Joined: Wed Sep 01, 2010 12:34 pm
Re: S9 Autoset SC Card Capacity?
Bob, my download settings are same as your example, yet you can see not much seems to be stored on the card. I usually just download each week's worth of data on Monday mornings, review, save .pdf reports on the computer, then close the program after telling it "Yes" I want to save the changes.
Right, the failure to utilize all the available memory capacity is what puzzles me. And, yes, I recall reading 7 days high rate data, 30 days detailed data, no more. It just seemed odd they'd supply it with a 1 Gig card when so little ends up getting stored on it. I'd really like to be able to store high rate data there and, once it's full, have data roll off into the bit-bucket on a first in first out basis, but I guess they didn't seem to think that was important for some reason.
Jeffster wrote:It writes 30 nights of detailed data to the SD card only. It writes 7 nights of high resolution flow data to the SD card only.
Right, the failure to utilize all the available memory capacity is what puzzles me. And, yes, I recall reading 7 days high rate data, 30 days detailed data, no more. It just seemed odd they'd supply it with a 1 Gig card when so little ends up getting stored on it. I'd really like to be able to store high rate data there and, once it's full, have data roll off into the bit-bucket on a first in first out basis, but I guess they didn't seem to think that was important for some reason.
- chunkyfrog
- Posts: 34548
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Re: S9 Autoset SC Card Capacity?
Am I right that some data is stored for a full year--then just rolls off the end?
Summary, maybe, or compliance for sure?
Summary, maybe, or compliance for sure?
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Additional Comments: Airsense 10 Autoset for Her |
Re: S9 Autoset SC Card Capacity?
Yes, you're right: "Compliance and therapy summary and statistic data (usage, AHI, pressure, and leak)"chunkyfrog wrote:Am I right that some data is stored for a full year--then just rolls off the end?
Summary, maybe, or compliance for sure?
_________________
Mask: Mirage Quattro™ Full Face CPAP Mask with Headgear |
Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
Re: S9 Autoset SC Card Capacity?
Perhaps the code responsible for this is from the S8 or an even earlier machine, and it reflects the limitations of earlier storage technology. Does anyone know how much data those proprietary smartcards hold?
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Re: S9 Autoset SC Card Capacity?
I have problems downloading the data graphs via ResScan 3.12, consistently. For a few days it works and other days it does not. If it does I see the graphs icon in the Browser data on the left. I been trying 2 GB and 8 GB SD cards and see no difference. In my S9 AutoSet I don't see any instructions about saving the data on the SD card. In the ResScan during the downloading, I pick the 5 days with details but before it's done it asks if to Overwrite or Discard and I click Overwrite. I don't know why. After I am done reviewing, it asks if to save the info and I click yes. But I don't know where it's being saved.
The most nuisance with ResScan is to convert the PDF graphs to a photo kind in order to save in Photobucket.com.
The most nuisance with ResScan is to convert the PDF graphs to a photo kind in order to save in Photobucket.com.
_________________
Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
Additional Comments: S9 Autoset machine; Ruby chinstrap under the mask straps; ResScan 5.6 |
see my recent set-up and Statistics:
http://i.imgur.com/TewT8G9.png
see my recent ResScan treatment results:
http://i.imgur.com/3oia0EY.png
http://i.imgur.com/QEjvlVY.png
http://i.imgur.com/TewT8G9.png
see my recent ResScan treatment results:
http://i.imgur.com/3oia0EY.png
http://i.imgur.com/QEjvlVY.png
Re: S9 Autoset SC Card Capacity?
And 365 days of summary data. It all is recorded round-robin, i.e., oldest data is overwritten by newest. The number of days of data is hard coded in the S9. There is no way to change it. If you want to save all your data on your PC you must download at least once a week. The 7, 30, & 365 day choices may have their roots in data card size of years past, but I speculate it also reflects how many days of data sleep doctors really care about, on average, when they review patients' data. Remember, Resscan and the data on the S9 is intended for doctors' use, not ours. They don't give a twit what we want. Resmed supplies the smallest most common card. If 512 mb cards were the cheapest, that's what we would get from them. I think I used one one time in my S9 with no problem at all.Slartybartfast wrote: Right, the failure to utilize all the available memory capacity is what puzzles me. And, yes, I recall reading 7 days high rate data, 30 days detailed data, no more. It just seemed odd they'd supply it with a 1 Gig card when so little ends up getting stored on it. I'd really like to be able to store high rate data there and, once it's full, have data roll off into the bit-bucket on a first in first out basis, but I guess they didn't seem to think that was important for some reason.
Click on discard, not overwrite. When you click on overwrite Resscan keeps only as much detail and hi-res data as there is on the card. When you select discard it tosses out the data off the card that is already in Resscan. It downloads all new data and adds it to the already stored data. It's a weird download option that doesn't really make sense, but that's the way it is. As long as you never sleep over the noon hour and download that afternoon and the next day also, you won't have any problems.avi123 wrote: In the ResScan during the downloading, I pick the 5 days with details but before it's done it asks if to Overwrite or Discard and I click Overwrite. I don't know why.
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Mask: AirFit™ P10 Nasal Pillow CPAP Mask with Headgear |
Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
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Re: S9 Autoset SC Card Capacity?
[quote="idamtnboy
Thanks, I started doing as you said.
Click on discard, not overwrite. When you click on overwrite Resscan keeps only as much detail and hi-res data as there is on the card. When you select discard it tosses out the data off the card that is already in Resscan. It downloads all new data and adds it to the already stored data. It's a weird download option that doesn't really make sense, but that's the way it is. As long as you never sleep over the noon hour and download that afternoon and the next day also, you won't have any problems.[/quote]avi123 wrote: In the ResScan during the downloading, I pick the 5 days with details but before it's done it asks if to Overwrite or Discard and I click Overwrite. I don't know why.
Thanks, I started doing as you said.
_________________
Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
Additional Comments: S9 Autoset machine; Ruby chinstrap under the mask straps; ResScan 5.6 |
see my recent set-up and Statistics:
http://i.imgur.com/TewT8G9.png
see my recent ResScan treatment results:
http://i.imgur.com/3oia0EY.png
http://i.imgur.com/QEjvlVY.png
http://i.imgur.com/TewT8G9.png
see my recent ResScan treatment results:
http://i.imgur.com/3oia0EY.png
http://i.imgur.com/QEjvlVY.png
Re: S9 Autoset SC Card Capacity?
I put together a post back in February to explain this in detail, but I never did get around to posting it. When I get home today, I'll pull it off my other computer and post it for everyone.Slartybartfast wrote:.. So why the need for such capacity if the S9 only utilizes a very small part of it?
...
Ray
Diagnosed in 1997
Diagnosed in 1997
Re: S9 Autoset SC Card Capacity?
As I mentioned in Pythone EDF library – To read cpap machine datalog files, I want to try to clear up at least some of the confusion regarding the Resmed S9 SD data card and the limits of data storage on it.
As many of us know, Resmed states that 365 days of summary data, 30 days of detailed data, and 7 days of high resolution data (HRD) can be stored on the SD card. I’ve also seen claims that, even with 1 year of high resolution data, that would only amount to about 30 Mb of data. I have no desire to check that value nor any reason to doubt it. Let’s just assume that it is correct for now. So then, why doesn’t Resmed allow 365 days of detail and HRD on the card? The answer is, with their decision to use the EDF data file format and SD cards, they simply can’t. Here’s why.
The Resmed S9 SD card has 1Gb of memory. A portion of that is used, in figurative terms, to lay down a grid that allows the computer to locate different files, very much like street addresses. The scheme used for this on ResMed memory cards is the FAT32 file system. Without going into a lot of computer details (which can be found in the previous link and other sources), what is important is that FAT32 on the Resmed SD cards can only address memory in 4 Kb chunks. That means a file with only a single character (or byte) in it will use 4 Kb (4096 bytes) of storage space on the card just like a file with 4096 bytes would. There isn’t a way around this without using a different, less universal, file system. This minimum size, in computer terms, is called the cluster size. Think of it this way – each of our houses vary in size, yet each of them have a single address. That’s exactly how computers access memory. If you need multiple locations at that address, suites, room/apartment numbers, etc are used in the real world. In computers, all you have is the address. If a file only has a single byte in it, the other 4095 don’t hold any data but the computer can’t access them either because all 4096 bytes share the same, single address. As long as that one byte file exists, the other 4095 bytes of memory are unreachable. I know this is not intuitive to many folks, but this is how computers work.
It’s important to know that each mask event (putting on, using, then removing the mask) creates 8 files. 4 of them contain data and 4 of them contain an 8 byte CRC value. CRC, or cyclic redundancy check values, are used to verify that a data file has not been tampered with. The 4 EDF files that contain the real data are:
*_BRP.EDF – contains high resolution flow and mask pressure readings, taken 25 times per second
*_EVE.EDF – contains data on each detected event on a per event basis
*_PLD.EDF – contains mask pressure, therapy pressure, expiratory pressure, leak, RR, ventilation, minute ventilation, snore index, FFL index, taken 2 times per second
*_SAD.EDF – pulse and SPo2, taken once each second (if no monitor is connected, the values are all zero)
At this point, I’ll make a few assumptions. The first is that our test person sleeps, on average, 8 hours a night and wakes up once each night (2 mask events). Let’s also assume this person has 4 events per night.
SADs, even though all readings are zero when no monitor is connected, seem to total about 100 Kb for 8 hours sleep, or 50 Kb for each mask event. A single event seems to create about 550 bytes of data so 4 events per night results in two 1 Kb EVE files. PLD files total about 110 Kb or 55 Kb per mask event. The big ones, BRP, seem to average about 350 Kb/hr, or 2800 kb per 8 hr night (1400 Kb per mask event for the 2 mask events in this example). Each CRC file holds 8 bytes of data, or about 0.008 Kb and there will be 8 of them for each night (4 per mask event).
The following chart shows how the space required for 1 year of this data, including HRD:
So, even if the data is only 30-40 Mb total for a year, because it is stored in a lot of small files (each of which uses 4Kb of space), it actually would take more than 1 Gb of storage space to store the full year with HRD included.
Limiting the HRD to 7 days and the detail data to 30 days, gives:
an easy fit.
Depending on how long a person sleep, how many time they wake up, and how many events they have, the numbers will obviously vary. But, as long as 5 of the 8 files contain very little data, a lot of storage space is lost due to the 4 Kb cluster size. That is not dependent on how a person sleeps. Since few of us sleep 8 hours undisturbed every night for a year, most people will have as many if not more files than these examples that waste a lot of space.
Given the variability in its patients sleep patterns, Resmed, had to insure there was enough space regardless of how each person sleeps in order to meet their 365/30/7 claim reliably. The only safe way to do that with a 1 Gb SD card using the open EDF format was to drastically reduce something. I suspect that HRD loses its clinical usefulness after a few days, since that is what they chose to limit. If it still had value, they wouldn’t have placed such a limit. In the long run, such a decision would cause a loss in market share if the RRTs and MDs were not getting what they needed to treat patients. As idamtnboy mentioned earlier, detail data beyond 30 days probably doesn't have much clinical usefulness either. I know that my pulmonologist isn't interested in older data.
But please, don’t take my word for the cluster size implication. Open explorer (for Windows users – I’m sure Mac has something similar) and navigate to your SD card. Right click on any of the CRC files and choose Properties. It will show the Size is 8 bytes, but the Size on disk is 4096 bytes. That is why a year’s worth of data including HRD cannot fit on a 1 Gb card. And, since it appears that Resmed has written their firmware to 365/30/7 day limits, using a larger card won’t help.
I don’t know why they chose the specific 365/30/7 day limits. I just know that with their current file scheme, they couldn’t reliably, if at all, store 365 days of details and HRD on a 1 Gb SD card.
As many of us know, Resmed states that 365 days of summary data, 30 days of detailed data, and 7 days of high resolution data (HRD) can be stored on the SD card. I’ve also seen claims that, even with 1 year of high resolution data, that would only amount to about 30 Mb of data. I have no desire to check that value nor any reason to doubt it. Let’s just assume that it is correct for now. So then, why doesn’t Resmed allow 365 days of detail and HRD on the card? The answer is, with their decision to use the EDF data file format and SD cards, they simply can’t. Here’s why.
The Resmed S9 SD card has 1Gb of memory. A portion of that is used, in figurative terms, to lay down a grid that allows the computer to locate different files, very much like street addresses. The scheme used for this on ResMed memory cards is the FAT32 file system. Without going into a lot of computer details (which can be found in the previous link and other sources), what is important is that FAT32 on the Resmed SD cards can only address memory in 4 Kb chunks. That means a file with only a single character (or byte) in it will use 4 Kb (4096 bytes) of storage space on the card just like a file with 4096 bytes would. There isn’t a way around this without using a different, less universal, file system. This minimum size, in computer terms, is called the cluster size. Think of it this way – each of our houses vary in size, yet each of them have a single address. That’s exactly how computers access memory. If you need multiple locations at that address, suites, room/apartment numbers, etc are used in the real world. In computers, all you have is the address. If a file only has a single byte in it, the other 4095 don’t hold any data but the computer can’t access them either because all 4096 bytes share the same, single address. As long as that one byte file exists, the other 4095 bytes of memory are unreachable. I know this is not intuitive to many folks, but this is how computers work.
It’s important to know that each mask event (putting on, using, then removing the mask) creates 8 files. 4 of them contain data and 4 of them contain an 8 byte CRC value. CRC, or cyclic redundancy check values, are used to verify that a data file has not been tampered with. The 4 EDF files that contain the real data are:
*_BRP.EDF – contains high resolution flow and mask pressure readings, taken 25 times per second
*_EVE.EDF – contains data on each detected event on a per event basis
*_PLD.EDF – contains mask pressure, therapy pressure, expiratory pressure, leak, RR, ventilation, minute ventilation, snore index, FFL index, taken 2 times per second
*_SAD.EDF – pulse and SPo2, taken once each second (if no monitor is connected, the values are all zero)
At this point, I’ll make a few assumptions. The first is that our test person sleeps, on average, 8 hours a night and wakes up once each night (2 mask events). Let’s also assume this person has 4 events per night.
SADs, even though all readings are zero when no monitor is connected, seem to total about 100 Kb for 8 hours sleep, or 50 Kb for each mask event. A single event seems to create about 550 bytes of data so 4 events per night results in two 1 Kb EVE files. PLD files total about 110 Kb or 55 Kb per mask event. The big ones, BRP, seem to average about 350 Kb/hr, or 2800 kb per 8 hr night (1400 Kb per mask event for the 2 mask events in this example). Each CRC file holds 8 bytes of data, or about 0.008 Kb and there will be 8 of them for each night (4 per mask event).
The following chart shows how the space required for 1 year of this data, including HRD:
So, even if the data is only 30-40 Mb total for a year, because it is stored in a lot of small files (each of which uses 4Kb of space), it actually would take more than 1 Gb of storage space to store the full year with HRD included.
Limiting the HRD to 7 days and the detail data to 30 days, gives:
an easy fit.
Depending on how long a person sleep, how many time they wake up, and how many events they have, the numbers will obviously vary. But, as long as 5 of the 8 files contain very little data, a lot of storage space is lost due to the 4 Kb cluster size. That is not dependent on how a person sleeps. Since few of us sleep 8 hours undisturbed every night for a year, most people will have as many if not more files than these examples that waste a lot of space.
Given the variability in its patients sleep patterns, Resmed, had to insure there was enough space regardless of how each person sleeps in order to meet their 365/30/7 claim reliably. The only safe way to do that with a 1 Gb SD card using the open EDF format was to drastically reduce something. I suspect that HRD loses its clinical usefulness after a few days, since that is what they chose to limit. If it still had value, they wouldn’t have placed such a limit. In the long run, such a decision would cause a loss in market share if the RRTs and MDs were not getting what they needed to treat patients. As idamtnboy mentioned earlier, detail data beyond 30 days probably doesn't have much clinical usefulness either. I know that my pulmonologist isn't interested in older data.
But please, don’t take my word for the cluster size implication. Open explorer (for Windows users – I’m sure Mac has something similar) and navigate to your SD card. Right click on any of the CRC files and choose Properties. It will show the Size is 8 bytes, but the Size on disk is 4096 bytes. That is why a year’s worth of data including HRD cannot fit on a 1 Gb card. And, since it appears that Resmed has written their firmware to 365/30/7 day limits, using a larger card won’t help.
I don’t know why they chose the specific 365/30/7 day limits. I just know that with their current file scheme, they couldn’t reliably, if at all, store 365 days of details and HRD on a 1 Gb SD card.
Ray
Diagnosed in 1997
Diagnosed in 1997