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May 20th, 2010 03:00
EMC_AX150_00-B slow transfer rates
We have the above emc unit that is split into 3 logical drives.
we have 3 dell 1950 servers connected to the emc unit via 2 power connect 6224 1 gb switches
each of the serves has 2 intel and 2 broadcom 1gb network cards in them.
1 intel and 1 broadcom ports are connected to each of the power connect switches which are then in turn connected to the emc storage unit.
1 server is running windows server 2003 32 bit complete with exchange ( exchange is local on D drive) acting as PDC
1 server running windows server 2003 32 bit hosting admin files on "F" 65 GB ( emc san) and sage accounts ( local on "D"
1 server running RHEL 5 this has 262 GB of data on the san
We are also running backup exec 11 to a tape drive from the exchange server.
We notice that one back job was running very slowly. We have been doing some transfer test we copied 1 folder from "F" on the sage server to the linux server 4.2Gb this took over an hour to transfer this. Then copied the same folder from the linux server to a desktop machine this took 14 min. thne ran the same process from the windows server from the desktop this took 32 min. ran the same process again with av off on the server and the transfer took 21 min.
We seem to be having very slow transfer rates form the san unit via the windows servers. I have disables the TOE function on the broadcom networks cards in windows as some did have an issue with backup exec with this. ( this did not make any difference to us on backup speed)
to give you some idea the linux server (not attached to the tape drive) has a back up of 254GB this take 3h 45 min the windows server ( not attached to the tape drive ) backs up 75 Gb in 3h 20 min.
Also it was a Dell engineer that set the San unit up to the servers. Anyone got any ideas why the transfer rate on the windows machines is so slow and the Linux server flys. Yes AV will be an issue but it can't amount for the transfer speed differences .
Also the desktop was reboot each time a transfer was complete so there was no residue of the previous file copy.
The San unit has 4 x 500GB SATAII HD 7.2K Dell
Thanks
Peter
Dev Mgr
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May 23rd, 2010 21:00
Several factors could play a role here. A few general guidelines:
- iSCSI traffic needs to be isolated from your LAN traffic by using dedicated (as in: not connected to the rest of your network) switches, or VLANs
- due to this traffic isolation, you need to use dedicated subnets for each iSCSI network/vlan that you use (see next note)
- assuming you have a dual controller model, iSCSI port 0 from each controller should be going to 1 switch using one subnet, iSCSI ports 1 from the 2 controllers should be on a different subnet.
- generally it's best to use the same brand NIC for all iSCSI connections (so 2 Intels or 2 Broadcoms, whether that's 1 port on 2 different cards or 2 ports on the same card). This ensures that you're using the same drivers for all iSCSI connections to 1 SAN
- if you have the dual SP model of the AX150i, do you have the UPS that came with the unit properly connected to allow the system to enable write cache (e.g. only plug this AX150 into it, hook up the serial cable to SPA and definitely do NOT put in the APC management card option as this kills the serial port (for proper EMC communication at least))
- if you have the single SP model, is the cache card working properly (doesn't show a fault)
- do you have an up to date version of Powerpath installed? (a version that's certified for your OS)
- is each server connection (with the iSCSI protocol) to all 4 iSCSI ports? The Navisphere Server Utility (in Windows) can establish the connections for you pretty easily, but it can also be done by hand in the iSCSI initiator.
petetc
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June 3rd, 2010 04:00
- iSCSI traffic needs to be isolated from your LAN traffic by using dedicated (as in: not connected to the rest of your network) switches, or VLANs
We have set up on a separate LAN
- due to this traffic isolation, you need to use dedicated subnets for each iSCSI network/vlan that you use (see next note)
Yes it is setup this way
- assuming you have a dual controller model, iSCSI port 0 from each controller should be going to 1 switch using one subnet, iSCSI ports 1 from the 2 controllers should be on a different subnet.
Yes we are set up like this
- generally it's best to use the same brand NIC for all iSCSI connections (so 2 Intels or 2 Broadcoms, whether that's 1 port on 2 different cards or 2 ports on the same card). This ensures that you're using the same drivers for all iSCSI connections to 1 SAN
Ok we have it set up using 1 port form the broadcom and 1 port from the Intel card ( redundancy Protection)
- if you have the dual SP model of the AX150i, do you have the UPS that came with the unit properly connected to allow the system to enable write cache (e.g. only plug this AX150 into it, hook up the serial cable to SPA and definitely do NOT put in the APC management card option as this kills the serial port (for proper EMC communication at least))
As far as i am aware we are set up as above.
I also found by turning the AV off on the windows server the backup ran as fast as the Linux server so the backup issue seems to be more to do with the AV , but i will look into you point about the Network Cards
Thanks for your reply