Is it possible to create a C: drive with 64K clusters?

[kolotyluk]

I'm trying to create a C: drive with 64K clusters - to match the block size of my RAID-0 drive. During the Windows 7 Setup process I drop into the command window with Shift-F10 and manually format the C: drive using

format c: /a:64k /x

then I continue with setup. Setup expands the files (seemingly normally) and then reboots, but when the system reboots I get

A disk read error occurred
Press Ctrl-Alt-Del to restart

If I reboot again it automatically reboots from the DVD.

I've tried this twice with the same results. I cannot tell if this is a bug in Windows 7 Setup, is a problem with the Dell system I am using, or if it is simply not supported to install Windows 7 this way.

If I use the default format from the Setup GUI, the installation works correctly.

Can someone please explain?

 

[iseeuu]

I'm trying to create a C: drive with 64K clusters - to match the block size of my RAID-0 drive.

I've tried this twice with the same results. I cannot tell if this is a bug in Windows 7 Setup, is a problem with the Dell system I am using, or if it is simply not supported to install Windows 7 this way.

Can someone please explain?

kolotyluk; Welcome to Seven Forums! Glad you dropped in.

I don't know that anyone has tried to do what you want to do. I believe as long as you use the "installer", it will create the default cluster best suited to Windows 7.

The only way I can see of getting 7 over a 64k partition it to use the 'upgrade' or 'repair' selection form the install DVD. Now you understand that anytime you experiment like this you are at risk of loosing all your DATA!? So make good backups before proceeding.

I have not done this so this is a quess: if you take an empty hard drive, you can use the 7 "Disk Management" utility to format it using 64k clusters.

Then you would have to COPY the contents of your current C drive to the new formatted partition. Connect only this drive and reinstall 7 via upgrade or repair. The installer should not reformat the drive and therefore should leave the 64k clusters alone. Now, and this is a big "Now", Windows 7 may simply not be able to function in a 64k environment so all your effort may be for nothing. You are welcome to try.

Have fun,
Robert

 

[kolotyluk]

Thanks for the info Robert - I have a sneaking suspicion that the problem is that Microsoft's boot loader cannot read a file system formatted with 64K clusters. It appears that Setup is correctly writing the O/S to the C: partition, and it writes a boot loader to the boot blocks on the drive, then it reboots to finalize the installation, but the boot loader is too simple to read the file system on the C: partition so it complains "A disk read error occurred."

I would imagine this is a scenario Microsoft have never tested before. Of course I don't know this is the case for sure, but I'm wondering if there is any way to get someone from Microsoft to confirm it. It would be another thing entirely to get someone from Microsoft to fix the problem.

Cheers, Eric Kolotyluk

 

[Antman]

In your BIOS, increase your PCI bus latency by single steps. Test.

You have been advised earlier in this thread to archive the data on the disk(s). Remove all other disks from the machine before playing with this trick.

 

[Antman]

Also note: You may actually reduce the performance of your RAID0 with 64k blocks. Any files smaller than 64k will reside on a single disk within the volume, disaffecting the benefit of multi-head seeks/reads/writes.

 

[Dinesh]

In addition to Antman's post, I would also like to recommend to turn off integrated audio and NIC.

 

[Dinesh]

Also note: You may actually reduce the performance of your RAID0 with 64k blocks. Any files smaller than 64k will reside on a single disk within the volume, disaffecting the benefit of multi-head seeks/reads/writes.

I guess the default is 128k?

 

[Antman]

I guess the default is 128k?

Cluster size, stripe size - not the same thing.

 

[Dinesh]

Cluster size, stripe size - not the same thing.

oh i was talking about the strip size. thanks for the correction.

 

[kolotyluk]

In your BIOS, increase your PCI bus latency by single steps. Test.

You have been advised earlier in this thread to archive the data on the disk(s). Remove all other disks from the machine before playing with this trick.

I'm curious why you think this would have an effect? The block size of the RAID is already 64K, so the I/O operations over the PCI bus would already be 64K wouldn't they?

The system boots fine when C: is 4K clusters (the default), but not for 64K clusters - which is why I suspect a boot loader problem.

Thanks for the warning, but there is nothing I need to archive as this is a test box I'm playing with and I've been reinstalling Windows 7 from scratch each time.

Cheers, Eric

 

[kolotyluk]

Also note: You may actually reduce the performance of your RAID0 with 64k blocks. Any files smaller than 64k will reside on a single disk within the volume, disaffecting the benefit of multi-head seeks/reads/writes.

Yes, this is not ideal for small files, but the application I have is based on processing images hundreds of megabytes (or larger) so I'm trying to optimize large file performance.

What I am trying to understand is if cluster size impacts large file performance. In this particular case I'm curious if matching the cluster size to the RAID block size helps at all - in such a case each file system operation to the disk will equal one RAID operation (I imagine).

Cheers, Eric

 

[Antman]

I'm curious why you think this would have an effect? The block size of the RAID is already 64K, so the I/O operations over the PCI bus would already be 64K wouldn't they?

The system boots fine when C: is 4K clusters (the default), but not for 64K clusters - which is why I suspect a boot loader problem.

Thanks for the warning, but there is nothing I need to archive as this is a test box I'm playing with and I've been reinstalling Windows 7 from scratch each time.

Cheers, Eric

You are waiting for two or more distinct physical actions to occur and register within the disk controller. Increase the latency value to compensate for a longer (combined) wait state.

A long standing adjustment known to address similar issues.

BUT NOT ON MS! Never mind. Unconfirmed but from an engineer I trust - private communication not for publication.

I was just directed to a reference that MS, beginning with XP SP2, only allows a max of 8k clusters on the boot volume. XP SP1 was the last MS OS that will allow this.

M3a79-t raid problems - Guru3D.com Forums
See post #4

 

[kolotyluk]

oh i was talking about the strip size. thanks for the correction.

The default cluster size for NTFS is 4K - that is all file system operations to the disk controller are performed 4K bytes at a time. With 64K clusters, operations are performed 64K bytes at a time.

The default block size for many RAID systems is 128K (mine included). This means RAID controller operations to disk are performed 128K bytes at a time - or 128K is written to each disk in the RAID until moving on to the next disk.

I don't like using the term stripe size as different people use it differently. To some people stripe-size = block-size * number-of-disks, whereas other people assume stripe-size means block-size.

Looking at various benchmarks I have found that block sizes over 64K usually offer little extra performance increase. This is likely because many I/O controllers have been optimized to perform operations 64K bytes at a time - typically 8 DMA operations of 8 KB at once before having to reprogram the DMA controller for the next operation.

Cheers, Eric

 

[kolotyluk]

You are waiting for two or more distinct physical actions to occur and register within the disk controller. Increase the latency value to compensate for a longer (combined) wait state.

A long standing adjustment known to address similar issues.

BUT NOT ON MS! Never mind. Unconfirmed but from an engineer I trust - private communication not for publication.

I was just directed to a reference that MS, beginning with XP SP2, only allows a max of 8k clusters on the boot volume. XP SP1 was the last MS OS that will allow this.

M3a79-t raid problems - Guru3D.com Forums
See post #4

OK, I just tried formatting C: with 8K clusters, and I get the same "A disk read error occurred" when the system reboots.

What did you mean by "XP SP1 was the last MS OS that will allow this?" Do you mean that prior to XP SP2 it was possible to have a boot volume with larger than 8K clusters?

Do you think I should still try tweaking the PCI latency?

Cheers, Eric

 

[RichB]

I did this in a trial

It took me some trial and error, but I managed to get the C drive to 64k clusters. You'll need to preformat the drive, and leave enough space for Win7 to create a boot partition of 100mb.

 

[Antman]

Do you mean that prior to XP SP2 it was possible to have a boot volume with larger than 8K clusters?

Do you think I should still try tweaking the PCI latency?

1. That is what my friend told me by phone this morning (I just happened to be speaking with him - I did not call to ask). I do not know otherwise. Throw in an XP <SP2 and try.

2. The setting is there for a reason. It is also a known adjustment to deal with some RAID/controller issues. Do I know if it will affect your situation - no. You have stated that no data is at risk. Estimated time on task: < 5 minutes. Time invested to this point: > 5 minutes.

 

[kolotyluk]

It took me some trial and error, but I managed to get the C drive to 64k clusters. You'll need to preformat the drive, and leave enough space for Win7 to create a boot partition of 100mb.

Sounds like what I'm looking for, but can you please give me some more details. Will windows automatically create the boot partition? Should I just leave 100 MB or so before the C: partition?

Cheers, Eric

 

[Antman]

It took me some trial and error, but I managed to get the C drive to 64k clusters. You'll need to preformat the drive, and leave enough space for Win7 to create a boot partition of 100mb.

Did you use a method as described at Guru3D? Can you elaborate?

 

[kolotyluk]

1. That is what my friend told me by phone this morning (I just happened to be speaking with him - I did not call to ask). I do not know otherwise. Throw in an XP <SP2 and try.

2. The setting is there for a reason. It is also a known adjustment to deal with some RAID/controller issues. Do I know if it will affect your situation - no. You have stated that no data is at risk. Estimated time on task: < 5 minutes. Time invested to this point: > 5 minutes.

OK, I'll have to hunt around for an old XP installer - now I'm curious.

I checked the BIOS setting on my Dell Optiplex 960 - there is nothing there for the PCI latency.

Cheers, Eric

 

[Antman]

OK, I'll have to hunt around for an old XP installer - now I'm curious.

I checked the BIOS setting on my Dell Optiplex 960 - there is nothing there for the PCI latency.

Cheers, Eric

Dell=Don't Even LLook for mods.