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EVA4100 and SQL allocation unit size when formatting drive.

 
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Regular Advisor

EVA4100 and SQL allocation unit size when formatting drive.

What is the best practice for formatting a partition after using diskpart to set alignment to 32kb? Is it to keep the allocation unit size to default of 4kb or set it higher?
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Honored Contributor

Re: EVA4100 and SQL allocation unit size when formatting drive.

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Honored Contributor

Re: EVA4100 and SQL allocation unit size when formatting drive.

You cannot use file system compression with clusters larger than 4KB. Here is a Microsoft Knowledge Base article with some additional discussion, enjoy:

http://support.microsoft.com/kb/140365/en-us
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Regular Advisor

Re: EVA4100 and SQL allocation unit size when formatting drive.

UWE,
From an EVA4100 standpoint do not do a disk alignment and keep the partition cluster size to default of 4kb is best practice? Reason I ask is I see so many write up's for SQL 2005 that recommend to partition a volume with cluster size larger like 64k for database.
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Honored Contributor

Re: EVA4100 and SQL allocation unit size when formatting drive.

Ah, it is unlikely that you will compress SQL databases, will you? ;-) In that case I would follow the SQL best practice and go with a larger cluster size.

A few days ago I have read that one of the analyzers (don't recall the exact name right now) complains if a data partition is not aligned. Now, if not aligning a partition does not hurt in an EVA environment, I doubt it will hurt if you _do_ align.

So, I would align the data partition(s) and run with the suggested cluster size.
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Regular Advisor

Re: EVA4100 and SQL allocation unit size when formatting drive.

So what is the recommended alignment for EVA? Im assuming 32kb= 64 sectors?

align=16
align=32
align=64
?
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Honored Contributor
Solution

Re: EVA4100 and SQL allocation unit size when formatting drive.

Yes, on the EVA3000/5000 it was 64 blocks.

The EVA chunk size is 128KB. If you use a cluster size of 64KB, I suggest you use a 64KB/128blocks offset so that NTFS clusters do not cross EVA chunks. If doing otherwise would have a negative impact on performance can only be said if it is tested.
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Regular Advisor

Re: EVA4100 and SQL allocation unit size when formatting drive.

Someone from HP told me to do

CREATE PRIMARY PARTITION ALIGN=32

Which would probably be causing my issue. Also if you let windows it automatically it will set the offset to 32kb. I guess I will try 64kb and see what happens.

Our Universe database vendor recommended 16kb offset.
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Honored Contributor

Re: EVA4100 and SQL allocation unit size when formatting drive.

Hi,
The general SQL recommendation is using a 64KB bock size during the format.
Partition alignment is also recommended.
You can use the diskpart command line as follows:
CREATE PARTITION PRIMARY ALIGN=64
and then format the disk

the pain is one part of the reality
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Regular Advisor

Re: EVA4100 and SQL allocation unit size when formatting drive.

Per this sql guide
"When using DISKPAR, adjust the alignment by 512 bytes, and when using DISKPART, the disk should be aligned to 64. The reason for this is due to the original master boot record design of WinTel based systems. The master boot record for all drives is 63 blocks (1 block = 512 bytes)."


Doesn't this mean that you should set align=32kb since 32kb is equal to 64 blocks? (64x1024=32,768kb.)

I do format the partition using 64k but I leave the alignment=32kb.