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NetApp and VM Alignment

K

KapsZ28

2[H]4U
Joined
May 29, 2009
Messages
2,114
I am trying to understand more about LUN alignment and what I am seeing on our NetApp. If I log into the filer and run “lun show –v”, only one LUN shows as being “aligned”. All the rest say “Alignment: partial-writes”. Three of the LUNs I just created today and they also say “partial-writes”.

Below is the output from one of the heads including a couple of LUNs using the “lun alignment show” command. My main concern is, is this something I should be concerned about? Is it going to affect performance?

Below is a screen shot from the NetApp Virtual Storage Console. None of the datastores show as Optimized and I am not really sure how to optimize them. There are also a couple of VMs showing as “Misaligned, Offline alignment only”. To align these VMs, does it just require that they are migrated through the VSC? If so, when I click on Migrate, it doesn’t show any usable datastores that I can migrate to. My only option would be to create a new datastore. Why is that, and does it have to do with none of our LUNs being aligned?

Code: 
head1a*> lun show -v
        /vol/cust_fx/cust_fx    1.0t (1099529453568) (r/w, online, mapped)
                Serial#: 
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=6
                Occupied Size:  665.6g (714672140288)
                Creation Time: Sun Mar  8 11:31:16 EDT 2015
                Alignment: aligned
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled
        /vol/cust__vol/cust-Vol0    250g (268435456000)  (r/w, online, mapped)
                Serial#:
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=3
                Occupied Size:   84.7g (90991693824)
                Creation Time: Tue Oct  7 14:37:20 EDT 2014
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled
        /vol/temp_vol/temp             8t (8796093022208) (r/w, online, mapped)
                Serial#:
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=5
                Occupied Size:    6.3t (6972420259840)
                Creation Time: Sun Mar  8 11:22:03 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: disabled
                report-physical-size: enabled
                Read-Only: disabled
        /vol/vol0/vol0                 2t (2199023255552) (r/w, online, mapped)
                Serial#:
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=10
                Occupied Size:  176.5g (189473546240)
                Creation Time: Wed Mar 18 10:04:22 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled
        /vol/vol1/vol1                 2t (2199023255552) (r/w, online, mapped)
                Serial#:
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=11
                Occupied Size:  137.5g (147637051392)
                Creation Time: Wed Mar 18 10:05:20 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled
        /vol/vol2/vol2                 2t (2199023255552) (r/w, online, mapped)
                Serial#:
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=12
                Occupied Size:  131.3g (141033369600)
                Creation Time: Wed Mar 18 10:06:00 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled


head1a*> lun alignment show /vol/temp_vol/temp
        /vol/temp_vol/temp
                Multiprotocol type: vmware
                Alignment: partial-writes
                Write alignment histogram percentage: 39, 0, 4, 0, 0, 7, 0, 28
                Read alignment histogram percentage: 16, 0, 66, 0, 0, 0, 0, 8
                Partial writes percentage: 19
                Partial reads percentage: 6
head1a*> lun alignment show /vol/vol0/vol0
        /vol/vol0/vol0
                Multiprotocol type: vmware
                Alignment: partial-writes
                Write alignment histogram percentage: 30, 0, 0, 0, 0, 0, 0, 0
                Read alignment histogram percentage: 51, 0, 0, 0, 0, 0, 0, 0
                Partial writes percentage: 69
                Partial reads percentage: 47

 
If the blocks are not aligned, the data spans more than one block, wasting space.
 
and fills a different set of caches and other bits on teh array that are far more limited in performance.
 
My bad, I forgot the two VMs in the example are Windows Server 2003. So that is why they aren't aligned. But I don't get the storage portion of it especially with NetApp.

Below are two datastores that I created in vSphere using the NetApp Virtual Storage Console. You'll notice that the one called "Test_Optimized_7" says "Yes" for Optimized. That datastore was created when I went through the Migrate wizard to align another VM. The datastore called "vol3" I also used the VSC, but I did so from the Datastores view by right clicking, selecting NetApp VSC, then Provision Datastore. See screen below. Unlike the optimized one, "vol3" says "No" for Optimized.... So it seems the only way for me to create an optimized LUN is to do it when using the migration wizard to align a VM. Does that mean all my LUNs need to be created this way, or do they not need to show as Optimized?

Besides the two Server 2003 VMs, the only other VMs showing as misaligned are pfSense VMs running FreeBSD. Does this mean I just need a specific optimized LUN just for these two operating systems and the rest can be on a standard LUN?

Lastly, if you look at the "lun show -v" for the two LUNs I am talking about, the difference is the Optimized LUN has three additional properties for Prefix Size, Suffix Size, and Extent Boundary.

Actually I think I get it now. When I create a LUN the standard way it has an offset of 0 which is fine for almost all VMs. For Windows Server 2003 and FreeBSD is seems I need to create LUNs with an offset of 7 for them to be properly aligned. I wish I had learned more about storage sooner.





Code: 
/vol/vol3/vol3               2.0t (2147752083456) (r/w, online, mapped)
                Comment: 
                Serial#: 
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Maps: EWR1-VPS-Hosts=1
                Occupied Size:    8.1g (8679297024)
                Creation Time: Thu Mar 19 13:19:43 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled


/vol/Test_optimized_7/Test_optimized_7  500.3g (537201213440)  (r/w, online, mapped)
                Comment: 
                Serial#: 
                Share: none
                Space Reservation: disabled
                Multiprotocol Type: vmware
                Prefix Size:       3.5k (3584)
                Suffix Size:          0 (0)
                Extent Boundary:       0 (0)
                Maps: EWR1-VPS-Hosts=0
                Occupied Size:    8.1g (8668614656)
                Creation Time: Thu Mar 19 09:28:57 EDT 2015
                Alignment: partial-writes
                Cluster Shared Volume Information: 0x0
                Space_alloc: enabled
                report-physical-size: enabled
                Read-Only: disabled
 
or you can use the netapp tools to align the guest instead.

edit: Or buy a platform that doesn't have issues with misaligned guests.
 
lopoetve said:
or you can use the netapp tools to align the guest instead.

edit: Or buy a platform that doesn't have issues with misaligned guests.
Click to expand...

Ha. I don't think I want to mess around too much with the pfsense OS and hopefully the Server 2003 is going away soon. Client's app is behind on the times. The upgrade will be to Server 2008, not R2.
 
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