Possible Alignment Issue on our Ghosting Server

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KapsZ28

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I don't really understand much about alignment and offset, but I need to figure out if our RAID volume is not running properly. First I used AS SSD Benchmark to see what it said and it displays BAD. Screen shot below.

I also ran wmic to display the Offset. Screen shot also below.

The is a Dell PowerEdge 2900 with five 15k SAS drive all setup in a RAID 5 configuration with Windows Server 2003 installed. I checked everything in the Dell OpenManage Server Administrator page and everything shows as green.

This server is primarily used for ghosting images.

So, what do you think? Do we have a problem? If so, how do I correct it?

Alignment.jpg


Offset.jpg
 
This tool will tell you how to check if the SSD offset is properly set.

http://www.techpowerup.com/articles/other/157

Based on what I see there, that SSD is not properly aligned.

A clean Win7 install should set it properly, using any other method to install the OS may not (usually doesn't) work. Using an OS other than Win7 will require tinkering as only Win7 knows what to do with an SSD properly.
 
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Limahl said:
This tool will tell you how to check if the SSD offset is properly set.

http://www.techpowerup.com/articles/other/157

Based on what I see there, that SSD is not properly aligned.

A clean Win7 install should set it properly, using any other method to install the OS may not (usually doesn't) work. Using an OS other than Win7 will require tinkering as only Win7 knows what to do with an SSD properly.
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Huh? This is neither SSDs or Windows 7. This is a production Windows Server 2003 with SAS drives. Just reinstalling the OS is not going to happen.
 
KapsZ28 said:
Huh? This is neither SSDs or Windows 7.
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Then why are you running an SSD benchmarker on it? Of course it's going to say the alignment is bad if it isn't an SSD.
 
Limahl said:
Then why are you running an SSD benchmarker on it? Of course it's going to say the alignment is bad if it isn't an SSD.
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I am not running any benchmarks. I just used the software to check partition D as I do not know how check the alignment. I am hoping some server techs can help out with this one.
 
KapsZ28 said:
I am not running any benchmarks. I just used the software to check partition D as I do not know how check the alignment. I am hoping some server techs can help out with this one.
Click to expand...

My point was that using SSD software on a non-SSD device isn't going to give you usable information, hence why it says "BAD". Of course it will say "BAD", thats not an SSD drive you're having it scan.

This article here may be of some use to you.

http://www.tcpdump.com/kb/os/windows/disk-alignment/check-disk.html

After running this utility, most will find a starting offset of 32256 (or 31.5 KB.) This is the default offset for Windows Server 2000, 2003 and Windows XP. But, it’s not the end of the world. So long as the affected volume is not running RAID, although not ideal, you’ll be ok. Having a boot volume that is not aligned is also not uncommon; just make sure that your data or I/O intensive volumes are. But if you find your exchange or SQL volumes are not aligned, well, then you have some work ahead of you.
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I tried the script, but unfortunately it just gives me an overflow error when checking the partition that I need to see if it is aligned.

NotAligned.jpg
 
KapsZ28 said:
I tried the script, but unfortunately it just gives me an overflow error when checking the partition that I need to see if it is aligned.
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My point was that using SSD software on a non-SSD device isn't going to give you usable information,
Click to expand...
AFAIK alignment is only applicable to SSDs.


but I need to figure out if our RAID volume is not running properly.
Click to expand...
Cool but it's got nothing to do with alignment.
 
Old Hippie said:
AFAIK alignment is only applicable to SSDs.
Click to expand...

Nope, just that it's determined differently on SSD's than on HD's, and older OS's have no clue what needs to be done differently with an SSD.

I did find this on a quick Google search while I wasn't logged into my VPN here at work, not sure if it helps at all.

To summarize the thread, when dealing with RAID0 or RAID5, to get optimal performance you need to use aligned partitions, ideally created at offsets of 1024KB x (number of usable drives in array). The overall best stripe size to use for the best read, write performance for all filesizes is 32KB. The best cluster size to use when formatting the partition with NTFS is 32KB when storing a variety of filesizes on the array. If you are only dealing with very large files on the array (256MB+), you can get the best performance by using a 128KB stripe size for the RAID array and a 64KB cluster size for the NTFS partition. I store a variety of files on my RAID array, so I use the 32KB stripe/32KB cluster option.

The next thing you need to do is create an aligned first partition on the array. If you use Windows Vista or later to create a partition it will create an aligned first partition by default. If you are using Windows XP, then you need to use a utility called diskpar.exe (not diskpart.exe since the XP version does not have partition alignment capability, but Windows Server 2003's diskpart.exe, and Vista and later's diskpart.exe do). You can gain slightly more performance by manually aligning the partition yourself using diskpar/diskpart. If you have a 5 disk RAID5 array, you would align the first partition on the array to 4096KB, or 1024KB for every non-parity (i.e. usable) drive in the array. For a 3 disk RAID5 array, you would align on 2048KB.

Yes, you can get awesome RAID5 write speeds on an Intel onboard RAID controller using the information above. My 5 disk RAID5 array with Samsung F1 500GB drives has a maximum read speed of 350MB/s and write speeds of nearly 300MB/s. They trail off linearly as you get further into the array just as any mechanical HDD's performance does when looking at HDtach/HDTune benchmarks. You're never going to get read and write speeds that match a RAID0 array with the same number of drives, but with proper stripe/cluster/alignment you can get close. For comparison, the same 5 drives in RAID0 have a max read speed of 450MB/s and write speeds over 400MB/s. On ICHR chipsets, RAID0 arrays are not severely hampered by non-aligned partitions, but alignment does help quite a bit. For RAID5, partition alignment is essential for good write performance.

Diskpart.exe usage (done on a clean drive/array with no partitions):
1) Open a command prompt window and type diskpart then hit Enter.
2.) Type: list disk then hit enter. Look for the disk number that corresponds to your RAID array
3.) Type: select disk 1 (if disk 1 is your RAID array)
4.) Type: create partition primary align 4096 (if you have a 5 disk RAID5 array, use 2048 if you have a 3 disk array)

That's it. Format the drive making sure to select the correct cluster size (at least 32KB). If you created a first partition that didn't fill the drive, any subsequent partitions you create on the drive will be aligned because the first one is aligned.
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it's pretty plain and simple; if the partitions were created during the Windows 2003 Server install, then the alignment will be incorrect; or if they were created in a XP-based pre-boot environment.

If you manually created the partitions using a tool like diskpart, and specified the offset, the alignment will be however you configured the offset. Which may or may not be correct.

I believe it was starting in Vista, the Windows install process would create the partition with the correct alignment.
 
KapsZ28 said:
I don't really understand much about alignment and offset, but I need to figure out if our RAID volume is not running properly. First I used AS SSD Benchmark to see what it said and it displays BAD. Screen shot below.
Click to expand...

what a bizarre thread. AS SSD to check a spinning disk based raid volume?

if your windows server o/s is booting correctly, what made you believe you have a problem that needs fixing? assumably this server has been running for a while if you're running windows 2003.
 
odditory said:
what a bizarre thread. AS SSD to check a spinning disk based raid volume?

if your windows server o/s is booting correctly, what made you believe you have a problem that needs fixing? assumably this server has been running for a while if you're running windows 2003.
Click to expand...

We actually have a problem with our outdated switch not working properly. The network team here is a pain in the ass and want us to verify there are no issues on the server. I used AS SSD because people in a previous thread had mentioned using it on my home server which is all mechanical drives setup in RAID 5. But like my very first sentence says. "I don't really understand much about alignment and offset, but I need to figure out if our RAID volume is not running properly." :p

Anyway, it appears the firmware and drivers on the server haven't been updated in probably years. I am now using the Dell OpenManage Server Update Utility to update everything and test it out.
 
Old Hippie said:
AFAIK alignment is only applicable to SSDs.

Cool but it's got nothing to do with alignment.
Click to expand...

Time to get out of the 60's and get with the new millenium. Did you know we landed on the moon?

j-sta said:
it's pretty plain and simple; if the partitions were created during the Windows 2003 Server install, then the alignment will be incorrect; or if they were created in a XP-based pre-boot environment.

If you manually created the partitions using a tool like diskpart, and specified the offset, the alignment will be however you configured the offset. Which may or may not be correct.

I believe it was starting in Vista, the Windows install process would create the partition with the correct alignment.
Click to expand...

Finally some logic entering this thread.

You need to use Diskpart to align your data volumes (you could use Diskpar, which is easier to use, but Diskpart is more-compatible). If your data volume is a paritition where your OS resides, you're SNAFU. All modern OS's partition-align at 1 meg offset, which is seen as 1048576 bytes when using MSINFO32.

64K offset will work, but 1 meg offset is more compatible with different stripe/file allocation unit sizes.

Data volumes are generally better formatted using 64K File Allocation Unit Size as well.

That being said, if you're doing large sequential file transfers, it's not going to affect performance much. If you have SQL loaded, then you better align the data partitions.
 
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