Posted by Unknown | Posted in Windows | Posted on 12:15 PM
This shows a semi-permanent paging file (brown)
You will notice that the paging file is split into two parts. The permanent part is at the outer tracks of the hard disk in one contiguous block. The lower, fragmented blocks of paging file are the dynamic part of the semi-permanent paging file. As the paging file requirement exceeds what the permanent part can provide, the dynamic part of the semi-permanent paging file will dynamically convert available hard disk space (which is usually on the inner tracks on the hard disk) into virtual memory.
Because the paging file's two components are at opposite ends of the hard disk, the hard disk heads will have to seek up and down the platters while servicing the paging file! Needless to say, that greatly degrades the performance of the paging file. The head seeks required to service a dynamic paging file are already bad enough. The amount of head seeks required to service both the permanent part and the fragmented dynamic part will definitely put a big dent on the paging file's performance.
Permanent Or Semi-Permanent?
Performance-wise, both a permanent and a semi-permanent paging file will perform equally, if the virtual memory requirement does not exceed what the permanent component of the semi-permanent paging file can provide. As the dynamic part comes into play, the semi-permanent paging file gradually loses its performance advantage over the dynamic paging file. Eventually, it may even become slower than a dynamic paging file.
The only way around this is to ensure that the permanent part of the semi-permanent paging file is enough to meet your usual virtual memory requirements. Do not look at the semi-permanent paging file as a way to save hard disk space. Instead, think of it as a permanent paging file with a backup capacity for dynamic expansion in emergencies!
Hard disk space is no longer that much of a premium as it was back in the old days. With desktop hard disks approaching half a terabyte in size, allocating a few hundred megabytes or even a gigabyte or so for the paging file isn't going to break anyone's heart. The performance of the paging file, especially in systems with very little RAM or for people who multitask a lot, is definitely more important than saving a few hundred megabytes of hard disk space.
Is Writing And Rewriting To The Same Area Dangerous?
Creating a permanent or semi-permanent paging file inevitably causes numerous writes and rewrites of information in the same fixed area of the hard disk platters. Compared to other areas of the hard disk, the space allocated to the paging file will be the area where data is most often written, deleted and replaced with newer data.
Some users have expressed concern over this fact. Will the platter media in that area get worn out after continuous use? Like the magnetic cassettes that we used to record our favourite songs? Will bad sectors form in that area like the floppy disks that have been written to once too often?
Well, unlike magnetic cassettes or floppy disks, there is actually no contact between the hard disk read-write heads with the platters. The read-write heads actually fly over the platters on a thin cushion of air. In fact, at the high speed that the platters are spinning at, any contact between a read-write head with a platter would have resulted in a head crash, with disastrous consequences.
Therefore, friction isn't the concern here. What about the effect of changing the magnetic properties of the media during the write process? Will the magnetic properties of the media deteriorate after too many of such changes? Or in the context of this article, will creating a permanent paging file damage the drive in the long run and reduce its MTBF (Mean Time Between Failures)?
To obtain a definitive answer to these questions, I contacted IBM and Seagate. Let's see what their technical experts have to say.
Seagate
This should not hurt the drive at all. As you are aware, the heads are actually suspended above the platters on an air bearing, so there is no direct contact with the media. As far as the recording and re-recording of the same tracks, also no problems. What we are dealing with here in order to write the data is simply moving the magnetic domain one way or the other, no wear involved.
Regards,
Bob
Seagate Tech Support
IBM
Remember, the heads truly fly above the media. The wear and tear factor only becomes an issue for bearings (heat) and physical damage to the media if the drive is shocked during operation. Performance is best at the outer tracks of the drive, so any recurring access directed there will benefit you in performance. Writing and rewriting data to a drive is good in that it remagnetizes (refreshes) the area every time it is written.
To answer your question: Your swap file will not affect the MTBF of your drive.
Don Gardner
IBM Hard Disk Technical Support/SIT Lab
So, Are Multiple Writes To The Same Area Good?
Well, it appears to be so. From what Don Gardner said, I gather that the signal carried by the media weakens with time and rewriting it refreshes and strengthens the signal strength of the data carried by the media.
I guess that pretty much answers our questions. Creating a permanent or semi-permanent paging file won't harm your drive. In fact, it might even be good for your data!
You will notice that the paging file is split into two parts. The permanent part is at the outer tracks of the hard disk in one contiguous block. The lower, fragmented blocks of paging file are the dynamic part of the semi-permanent paging file. As the paging file requirement exceeds what the permanent part can provide, the dynamic part of the semi-permanent paging file will dynamically convert available hard disk space (which is usually on the inner tracks on the hard disk) into virtual memory.
Because the paging file's two components are at opposite ends of the hard disk, the hard disk heads will have to seek up and down the platters while servicing the paging file! Needless to say, that greatly degrades the performance of the paging file. The head seeks required to service a dynamic paging file are already bad enough. The amount of head seeks required to service both the permanent part and the fragmented dynamic part will definitely put a big dent on the paging file's performance.
Permanent Or Semi-Permanent?
Performance-wise, both a permanent and a semi-permanent paging file will perform equally, if the virtual memory requirement does not exceed what the permanent component of the semi-permanent paging file can provide. As the dynamic part comes into play, the semi-permanent paging file gradually loses its performance advantage over the dynamic paging file. Eventually, it may even become slower than a dynamic paging file.
The only way around this is to ensure that the permanent part of the semi-permanent paging file is enough to meet your usual virtual memory requirements. Do not look at the semi-permanent paging file as a way to save hard disk space. Instead, think of it as a permanent paging file with a backup capacity for dynamic expansion in emergencies!
Hard disk space is no longer that much of a premium as it was back in the old days. With desktop hard disks approaching half a terabyte in size, allocating a few hundred megabytes or even a gigabyte or so for the paging file isn't going to break anyone's heart. The performance of the paging file, especially in systems with very little RAM or for people who multitask a lot, is definitely more important than saving a few hundred megabytes of hard disk space.
Is Writing And Rewriting To The Same Area Dangerous?
Creating a permanent or semi-permanent paging file inevitably causes numerous writes and rewrites of information in the same fixed area of the hard disk platters. Compared to other areas of the hard disk, the space allocated to the paging file will be the area where data is most often written, deleted and replaced with newer data.
Some users have expressed concern over this fact. Will the platter media in that area get worn out after continuous use? Like the magnetic cassettes that we used to record our favourite songs? Will bad sectors form in that area like the floppy disks that have been written to once too often?
Well, unlike magnetic cassettes or floppy disks, there is actually no contact between the hard disk read-write heads with the platters. The read-write heads actually fly over the platters on a thin cushion of air. In fact, at the high speed that the platters are spinning at, any contact between a read-write head with a platter would have resulted in a head crash, with disastrous consequences.
Therefore, friction isn't the concern here. What about the effect of changing the magnetic properties of the media during the write process? Will the magnetic properties of the media deteriorate after too many of such changes? Or in the context of this article, will creating a permanent paging file damage the drive in the long run and reduce its MTBF (Mean Time Between Failures)?
To obtain a definitive answer to these questions, I contacted IBM and Seagate. Let's see what their technical experts have to say.
Seagate
This should not hurt the drive at all. As you are aware, the heads are actually suspended above the platters on an air bearing, so there is no direct contact with the media. As far as the recording and re-recording of the same tracks, also no problems. What we are dealing with here in order to write the data is simply moving the magnetic domain one way or the other, no wear involved.
Regards,
Bob
Seagate Tech Support
IBM
Remember, the heads truly fly above the media. The wear and tear factor only becomes an issue for bearings (heat) and physical damage to the media if the drive is shocked during operation. Performance is best at the outer tracks of the drive, so any recurring access directed there will benefit you in performance. Writing and rewriting data to a drive is good in that it remagnetizes (refreshes) the area every time it is written.
To answer your question: Your swap file will not affect the MTBF of your drive.
Don Gardner
IBM Hard Disk Technical Support/SIT Lab
So, Are Multiple Writes To The Same Area Good?
Well, it appears to be so. From what Don Gardner said, I gather that the signal carried by the media weakens with time and rewriting it refreshes and strengthens the signal strength of the data carried by the media.
I guess that pretty much answers our questions. Creating a permanent or semi-permanent paging file won't harm your drive. In fact, it might even be good for your data!
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