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About cas

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  • Location
    Redmond, WA
  • Interests
    OS Design, Embedded Systems, Storage Networking, Telematics

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  1. cas

    Cas 2.5 or 2.0

    Did somebody ask about cas? A similar question was asked about a year and half ago. My response can be found here.
  2. cas

    Intel Pentium 4 with 64-Bit processing

    You recall incorrectly. Big real mode is a technique for entering protected mode on a 386+, bumping the segment limits to 4GB, and returning to real mode. 1. This is incompatible with 'regular' real mode in a number of subtle ways. 2. It doesn’t work on a 286, because the 286 was a 16 bit processor. 3. Even if it wasn’t, it still wouldn’t work because you can’t return to real mode on a 286.
  3. cas

    Intel Pentium 4 with 64-Bit processing

    Congratulations casa, you have entered protected mode and flushed your prefetch queue, but how do you propose to get out? The inability of the 286 to return to real mode without a reset was a serious limitation of the device. Bill Gates immediately pronounced the device “Brain Dead”, and insisted that Microsoft skip the 286 and focus exclusively on the 386. Gates lost, but the chip still sucked.
  4. cas

    Honold 3k posts....

    I am afraid that I have just been very hard at work. It was kind of you to miss me. But then, this is honold's thread.
  5. Each drive is assigned a GUID, and the GUIDs are then replicated in the LDM database on each of the drives in the array. If you install the array in another machine, you will have to 'Import Foreign Disks', but everything should work just fine.
  6. cas

    Honold 3k posts....

    You forgot CNN news clippings, and his various explanations about why he took people's money, and never delivered the goods they paid for. I haven't been around for a while, but you are certainly one of the few that makes SR worth reading. Kudos, and thanks for all the posts.
  7. Due to circumstances beyond my control, this project has been suspended indefinitely.
  8. cas

    DDR Memory Questions

    I describe the difference between CL2 and CL3 SDRAM here. DDR SDRAM is similar, except that double pumping means that latencies can be measured in half clocks (like CL2.5).
  9. I have been reading your posts for some time now, Frank. If you display half of the competence you have shown here, and go in knowing why manholes are round, the hiring manager would be a fool to turn you away.
  10. For hundreds of years, Americans have been inventing reasons to disparage any group of individuals willing to work hard, for less money. They came up with reasons to hate legal immigrants from Ireland, China, and Eastern Europe, as well as emancipated slaves from the South. Even when immigration is removed from the equation, trade unionists(and others) can often be found making similar remarks about workers in other countries because free markets make them a threat despite physical separation. I do not doubt that some of the posters here have had legitimately negative encounters with Indian engineers or IT specialists. However, the population of India is very large, and each man will stand on his own merits. The colleague I most respected in high school was brilliant, athletic, thoughtful and kind. He was an articulate speaker, and president of the student body; he was also Indian. He did not attend high school in the United States, yet his verbal skills in English would have put most Americans to shame. My previous employer was also Indian, having learned how to develop software at a University in India. He was an experienced manager of large scale development efforts, and I learned a great deal from his example. I am very fortunate that he did not have the same blanket policy towards those foreign to him, as some have shown here. There is no question that the ability to communicate clearly in English is a requirement for many jobs. To deny this would be an exercise in political correctness. To suggest that not one of the hundreds of millions of people in India possess this ability would be an exercise in stupidity. Furthermore, there is a class of jobs for which the ability to speak in English in secondary to the ability to write code. I rarely make these kinds of posts, and recognize that in this case it is squarely off-topic. There are some things however, which simply cannot stand.
  11. There is something else to consider as well. In the case of a disk to self copy, a 500MB file can often be done in a single pass if the PC has enough ram. Due to the limited RAM in most disks however, an autonomous copy would require a great deal of seeking, and would probably be much slower. Adding the heuristics necessary to determine which way to copy the files would require that still more details (like disk cache size) be exposed to the filesystem.
  12. In order to manage complex systems, we often create abstract models of what devices can do. The filesystem exposed model of what a disk can do (on any OS I am familiar with), includes reading and writing (plus a few other things), but not copying. Ideally, that model would be expanded to include copy and xor (for soft RAID) operations. The underlying system software could then invoke the hardware when the operations were supported, or emulate them in software when they were not. In the absence of such an abstraction, the determination of which blocks constitute an individual file must be determined at the application level. While you could probably copy from a mounted disk with some knowledge of the underlying filesystems and a defrag API, it’s pretty messy. Copying to a mounted filesystem would be an even bigger mess, and might require remounting the volume for each set of files copied. At the very least, some decent flush primitives would be required. Filesystems don’t particularly like new files to show up on their volumes, unannounced.
  13. Although support for the command is optional, SCSI has supported COPY for many years. This can be something as simple as moving data around on a single disk without loading the SCSI bus, or something as complex as a complete autonomous transfer from a disk to a tape. Due to limitations with COPY, SCSI-3 introduced the more sophisticated EXTENDED COPY that enables robust multi-part transfers across a storage fabric with almost no host intervention. While certain backup programs may use these commands, regular copy programs do not.
  14. cas

    Ah crap, now its all finished..

    Aw shucks :oops: You are very kind. We should have a chat about OS X sometime, it actually has much less to do with FreeBSD than many people think.
  15. Actually, this is not the case. All of the partitions and volumes for all of the dynamic disks in a system are maintained in a single database. That database is then replicated across every dynamic disk in the system. Older software does not work well with dynamic disks because they have not been updated to read the Veritas database records used by dynamic disks. Another consideration is that the dynamic disk driver strips the SL_WRITE_THROUGH flag from the write command. This is a bug, but it can result in higher performance. For more information, see the XP Cache Filter thread.