Lav skrivehastighet SCSI seagate 15k

[Nizzen]

Har et lite problem med min nye Seagate 15000 rmp 36 gig....

 

Den leser veldig raskt, men når jeg skal skrive til harddisken så går det bare i ca 14- 15 MB/s. Lesing fra disken går i ca 50-60 MB/s

 

Har en adaptec 29160LP kontroller som er i en pci slot på mitt

ic7-g hovedkort. P4 3,2.

 

Trenger jeg nye drivere eller er det noe annet galt... Sata diskene mine skriver jo i ca 50 MB/s...

[Nizzen]

Har hørt noe om at skrivehastighet på SCSI i win XP ikkje er helt bra av en eller annen grunn... kan det stemme? Kanskje jeg må bruke Windows 2000?

[Nizzen]

Nå har jeg prøvd Windows 2000 adv. Server og det er samme skriveproblemet til harddisken..... Må jeg bruke vanelig windows 2000?

[Nizzen]

Hater SCSI!?

 

[Nizzen]

Hurra det funka!!! Nå er skriveytelsen konge i windows 2000! Kanskje i win XP også! :w00t:

 

 

Why is Windows XP so bad with SCSI?

 

 

From StorageReview:

quote:

It's really time for us to close the thread 'Terrible SCSI Performance in Windows XP". 678 posts, and no one reads any of the previous information because there's too much of it. This leads to a kind of self-perpetuating rant, which serves no purpose other than to keep circulating a myth about SCSI and XP.

 

So here's the bottom line, followed by a FAQ.

 

Windows 2000 had a minor bug where application requests to write through the cache (i.e. ignore the drive/controller cache and write directly to the disc) were not honored. In other words, writes were being cached even if the application asked for them not to be cached. This provided artificially high write performance in Windows 2000 for such applications (which are rare). Unfortunately, a number of benchmarks (e.g. ATTO) incorrectly used the WRITE_THROUGH flag in an attempt to provide what they thought was the most accurate, uncached, performance result.

 

Windows XP correctly honors the WRITE_THROUGH flag for Basic disks. When people upgraded from Windows 2000 to Windows XP, and ran a benchmark like ATTO, they saw greatly "decreased" write scores. That's because the writes were no longer being cached. While this is an accurate measurement of totally uncached writes, it's not the kind of performance result that ATTO wanted to provide their users.

 

Many people found that changing from Basic to Dynamic disks in Windows XP "reclaimed" their performance in ATTO. This is because Microsoft forgot to fix the WRITE_THROUGH issue with the Dynamic disk code path. Dynamic disks do not "reclaim" any "lost" performance, because the performance was never lost. It's an artificial benchmark phenomenon. Oh, sure, some file copy operations were affected, because they were using the WRITE_THROUGH flag. That's by design to ensure files are copied/moved with integrity. It doesn't affect 99.9% of system performance on non-server platforms.

 

The next version of Windows will likely have a checkbox under the "enable write caching" checkbox in the disk properties, to turn on and off the ignore WRITE_THROUGH flag behavior (for people who are using battery-backup and/or UPS and are therefore sure of disk integrity). In the meantime, users can choose one behavior or the other by choosing Basic or Dynamic disks.

 

OK, so that's the bottom line, please read over it carefully. Here is the FAQ.

 

Q: Is there a Windows XP BUG that reduces SCSI performance?

A: Absolutely NOT.

 

Q: Should I move back to Windows 2000, or to some other OS, due to this issue?

A: No, read the opening statements of this post again.

 

Q: Is this a SCSI related issue? Does it affect IDE or IDE RAID?

A: This is in no way SCSI related. The only reason it occurs on SCSI-class devices (SCSI & IDE RAID) and not on standard IDE, is that IDE does not have a WRITE_THROUGH flag in its command set. This could be considered a flaw in the IDE specification, which I understand is due to be rectified in a future spec revision. Note that any IDE controller which has its own drivers is a SCSI-class device and will appear as such (e.g. Promise Ultra100) even if it isn't RAID.

 

Q: If this is just due to ATTO writes being uncached, why is my write performance SO SLOW? I should have xxMBps to the platter...

A: The only way you can truly have sequential writes is if they are cached in the drive buffer. Without a cache, you can only write a chunk at a time, and in between chunks, you'll have missed the heads coming around and have to wait on rotational latency. That's why you'll see writes peaking after a certain block sized is reached in ATTO.

 

Q: You said I could choose behaviors by using Basic or Dynamic disks. What if I have XP Home, which doesn't support Dynamic disks?

A: SCSI (and IDE RAID) are high-end / enthusiast platforms. It would be very unusual for anyone to run XP Home on such platforms. For example, workstation-class machines from Dell, HP, etc. are not even offered with XP Home.

 

Q: How do I convert to Dynamic disks?

A: Control Panel, Administrative Tools, Computer Management, Disk Management, right-click on "Disk n" and choose "Convert to Dynamic Disk". Read the online help about Dynamic Disks to make sure you understand the restrictions, etc.

 

Q: Does XP Service Pack 1 affect the issue?

A: No.

 

Q: I heard that Windows XP was "made for the masses" and therefore "isn't optimized for best performance". Are there any tweaks I can use to improve disk performance?

A: Not really. That whole "made for the masses" stuff sounds slick but in fact, XP is very self-optimizing. Defragment your disk often, delete temp files and temporary internet files first. Be aware of an IE bug that leaves extraneous files in your Temporary Internet Files\Content.IE5 directory under randomly generated temporary directory names (basically, it dumps a file there every time you hit Stop while a page is loading, or navigate to another page before a page completely loads). Establish a paging file on each physical drive. Ensure write caching is enabled (some SCSI controllers will cause the write caching flag to be turned off on every reboot unless you set the controller to turn on write caching in its BIOS). Avoid converting FAT32 to NTFS, format as NTFS in the first place.

 

Q: I think you're wrong about this, because I have xxx SCSI performance problem under Windows XP.

A: There are dozens of reasons you may be experiencing poor performance that have nothing to do with this issue, and are not due to any global issue with SCSI performance under Windows XP.

 

[Sir_cruz]

Du har hatt en intresang diskusjon med deg selv her ser jeg

 

Jeg har litt lyst på SCSI jeg også , men har rett og slett ikke ressuser til det