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In Reply to: RE: Any failure of hard disks in your NAS ? posted by Tony Lauck on November 19, 2014 at 09:58:39
Hi and sorry to disturb again
If i understand well a Ram disk inserted in the PCI (which one ?) slot reduce the I/O operations ?
Why not go further and increase the amount of the real RAM ?
some PC can use up to 16 GB (if not more)
Is it possible to do so ?
There is nothing like a speedy RAM i think when direct access is required
Thanks a lotP.S. i think this new family of SSD will make you change your take on SSD
http://www.maximumpc.com/ocz_trots_out_vertex_460a_ssd_series_using_toshiba_a19_nand_flash_2014
around 0.5 Gbps reading speed on a SATA 6Gbps channel (wow !)
allowed by the new 19nm Nand chip by Toshiba, i guess a great achievement indeedor better still ... wait a little bit for this ... SATA Express (16 Gbps !)
http://www.legitreviews.com/what-is-sata-express-and-why-it-matters_140093
the "PC world" is the only one that is getting better and better ... unfortunately
Kind regards,
bg
Edits: 11/19/14 11/20/14Follow Ups:
A RAM disk is not any separate physical component. It's just a device driver (software) that grabs a block of RAM at system boot, removing it from other use and creating the appearance that there's a separate disk device and file system.
For my Windows system I am using an older (free 4 GB) version of the software linked below. This was free, but I don't see a free version on the web page today. For Linux systems ram disk software is available for all distributions and can be installed and activated for free (assuming necessary Linux knowledge).
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Hi and thanks a lot now i understand better
Interesting solution indeed
I guess this is the most direct way to read data without possible bottleneck
A very high end solution
I wonder if the benefits would be evident also on an average playback system
I have to try of course
Thanks again.
Kind regards,
bg
First of all, for 2-ch audio playback there is no bottleneck at all within any modern PC or Mac. Audio playback is not resource, disk, or I/O intensive. It just isn't. You can use the slowest and very quiet 5400rpm 2.5" laptop drives which will be more than sufficient.Some folks use RAM disk so the music is pre-loaded and played out of RAM so the spinning disk drive is not being accessed while the music is playing. One theory is that if the disk heads are moving to access the music file, you might hear it.... or just the fact that there's a signal (noise) from the disk I/O, that might be an issue. All highly debatable stuff in terms of whether it matters or not, and the only way to determine any benefit is to try for yourself.
The benefit of using a RAM disk with SSD is also debatable. The SSD has no moving parts so who cares if it's being directly accessed while playing music. Some will say that the mere fact that it is being accessed might produce noise due to the I/O to the SSD. Again, in the weeds audiophile stuff. Try for yourself and see if it matters.
And finally, many music players like Audirvana Plus, Pure Music, and others incorporate their own form of RAM disk often called 'memory play'. Again, music is preloaded into your system RAM before playback so there are no disk or SSD I/O operations taking place while playing music.
As for experimenting with RAM disk, Tony had some comments on how to do it in Windows. Here's how on a Mac with no special additional software or drivers. Just some command line stuff in the Terminal window:
Create experimental 1GB RAM DISK on Mac
Disk Utility shows the 1GB RAMDISK
Edits: 11/20/14
I went to using a RAM disk because it bypassed using spinning rust. I was able to hear the noise made by the spinning rust while seeking. Also, I wanted to do the conversion from FLAC to WAV off line. If I had an SSD to use as a cache for music files then perhaps I would have done it differently. However, I don't think this is a good idea, as it creates a lot of write traffic to the SSD and may impact wear.
If your favorite player uses memory storage and this is done correctly it will be better to load the play list into the player's memory. This avoids processing the WAV file RIFF headers during real-time music playback. However, this is only feasible on a 64 bit operating system with lots of RAM if one has long playlists of high-res files. With this approach it is possible to completely suspend the operating system if the DMA controller for the audio output has enough addressing/counting capability.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Tony, when you do your FLAC to WAV conversion is that done 'on the fly' just prior to each music file being played? Or is it more of a batch process? I'm not sure I understand but it would make sense not perform a lot of unnecessary writes to the SSD, and doing your conversions in RAM will be lightning fast.
In most music server setups SSD write endurance isn't a problem because well over 90% of the operations to SSD will be reads. Besides, the endurance of MLC SSDs have gone up significantly just in the past couple years. So much so that the lines between MLC and SLC have blurred. Many enterprise class storage systems that used SLC SSDs have recently gone to MLC. SLC is already rare, very expensive, and likely to become unavailable in short order..... because it is too expensive and no longer cost effective.
I work as follows when playing FLAC files.
1. I open the folder containing the tracks of an album.
2. I select the tracks that I wish to play. (Typically several tracks, e.g. four tracks for four movements of a symphony.)
3. I right click on the selected tracks and Dbpoweramp converter converts these to WAV and stores them in the RAM disk.
4. I open HQPlayer and tell it to pick up all the tracks in the RAM disk.
5. I click play.
6. When done I close HQPlayer.
7. I clear out the RAM disk.
It would not be practical to do the conversion prior to each track as this would change the delay between tracks and add glitches to albums that were made to be played "gapless". The downside is that long play lists (e.g. Bach's St. Matthew Passion) can exhaust the size of the RAM disk that I have set up if they are hires. If this happened often I would upgrade the RAM disk from 4 GB to 8 GB, but then I would need to add more RAM to my computer, which presently has only 12 GB of RAM.
I have no idea whether or not SSDs have become reliable. They were not. As far as I can tell micro SD cards are still unreliable -- it's been only about two months since I lost data on one that was being used to do compiles and operating system updates on a Raspberry Pi. I recently got a 120 GB SSD that I am using on an Atom based NUC as a Linux server. This will get a pretty good thrashing due to data base updates. I will be pleasantly surprised if this device makes it through a year.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Hi Mr. Collins !
thanks a lot for the very helpful advice as always
The idea of direct memory access is very sane on principle
I will look for a Windows audio player SW with the Ram disk feature
As a second option i like very much SSD, that are getting bigger and faster any day
I have read something about the new NAND chips and i am impressed
They allow for 0.5 Gbit/s read and write speed
Transfer speeds almost at RAM levels and also " ... up to 95K read IOPS [input/output operations per second] ! ... "
Ok ... there will be still some I/O but this is very fast and not very expensive i hope.
Thanks a lot again.
Kind regards,
bg
Edits: 11/20/14 11/20/14
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