iscsi perfomance

[nettech1]

I have a Dell MD3000i with 5 SATA drives (RAID5) connected to a Dell 5424 switch.

ESXi 5.5 has two nics connected to the same switch for iscsi traffic.

The set up as follows:

MD3000i

RAID Controller 0,0 - 192.168.1.1 (Jumbo Frames set to 9000)

RAID Controller 0,1 - 192.168.2.1 (Jumbo Frames set to 9000)

RAID Controller 1,0 - 192.168.1.2 (Jumbo Frames set to 9000)

RAID Controller 1,1 - 192.168.2.2 (Jumbo Frames set to 9000)

Dell switch 5424 has jumbo frames enabled

ESXi has two vmkernal ports (1 for each nic) 192.168.1.10 & 192.168.2.10 and jumbo frames are set to 9000 on both.

when I read data (copy a 4GB file to a VM hosted on local storage of ESX) I get a steady 50MB/s transfer, but when I try to save something on SAN (copy the same 4GB file from desktop of a VM using local storage to SAN) the transfer starts at 270MB/s drops to a 0 somewhere in the middle and then flattens out at 50MB/s

Any ideas what could cause such a sporadic transfer rates?

Thanks

[JPM300]

The driver will update all network cards that have the chipset models it covers, so unforantly there isn't anyway to specify nice like in Windows, to my knowledge.

I also found this: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=208202...

which is a recent KB, not sure if it is applicible to you or not.  An easy way to test this is if you can get your hands on a Intel dual port nic that is on Vmware HCL and put that into the host, then just createa  new vSwitch/Portgroup then move the VM to this port group and see what the speeds are.   You could even try it with a different broadcom card if you have, however i've had a few quarky issues with the broadcom cards over the years.

I was also thinking about this one a little more, all your cables that are connected to that broadcom are tested GOOD and are cat5e or higher?

[nettech1]

All cables are tested good (cat5e 350mhz)

found a newer driver (3.136e.v55.1)

https://my.vmware.com/group/vmware/details?productId=353&downloadGroup=DT-ESXI55-BROADCOM-TG3-3136EV...

will try tonight

[JPM300]

Sounds good.  Let us know how it goes

[nettech1]

before

after

from MD3000 to MD3000 file transfer still chokes

[nettech1]

we see an improvement from MD3000 to local storage

writing back to MD3000 still suffers.

[vlho]

Hi,

what status have your cache in storage?

See on Subsystem Profile - Logical Drives,

should there be this:

Write cache                             - Enabled

Write cache without batteries    - Enabled

Write cache with mirroring         - Enabled

[nettech1]

Number of standard virtual disks: 1

      See other Virtual Disks sub-tabs for premium feature information.

      NAME     STATUS   CAPACITY  RAID LEVEL  DISK GROUP  DRIVE TYPE  

        san  Optimal  1.817 TB  5           san1    SATA        

   DETAILS

      Virtual Disk name:                      san1                                          

         Virtual Disk status:                 Optimal                                          

         Capacity:                            1.817 TB                                         

         Virtual Disk world-wide identifier:  60:02:6b:90:00:2d:fc:04:00:00:01:f8:53:bd:1e:64  

         Subsystem ID (SSID):                 0                                                

         Associated disk group:               GR1                                         

         RAID level:                          5                                                

         Physical Disk type:                  Serial ATA (SATA)                                

         Enclosure loss protection:           No                                               

         Preferred owner:                     RAID Controller Module in slot 0                 

         Current owner:                       RAID Controller Module in slot 0                 

         Segment size:                                       128 KB    

         Capacity reserved for future segment size changes:  Yes       

         Maximum future segment size:                        2,048 KB  

         Modification priority:                              High      

         Read cache:                            Enabled   

         Write cache:                           Enabled   

            Write cache without batteries:      Disabled  

            Write cache with mirroring:         Enabled   

         Flush write cache after (in seconds):  10.00     

         Dynamic cache read prefetch:           Enabled   

         Enable background media scan:          Enabled   

         Media scan with consistency check:     Enabled   

         Pre-Read consistency check:            Disabled  

[nettech1]

found something interesting about MD3000i http://crazyvlan.blogspot.com/2010/11/dell-md3000i-slow-write-speed-cache.html

[nettech1]

and this http://en.community.dell.com/support-forums/storage/f/1216/p/19279005/19657765.aspx#19657765

[JPM300]

Hmmm looks like lots of other people have had performance issues with the MD3000i.  Not sure what your next course of action is as everything on the ESXi side looks good.  Don't suppose you have a support contract with dell on this MD3000i still do you?>

[schepp]

The MDs performance rely heavily on the cache setting.

I managed to increase performance on some MD3260s with the right cache settings. Play with the settings. Everything on is not always good.

The cache mirroring for example will decrease performance.

Also increasing the cache block size worked wonders.

[nettech1]

MD3000i is still under support contract with Dell, opening a case with them to see what they can suggest to increase write performance.

[JPM300]

Nice, let us know if they find a resolution for you or what they have to say.