Ever since the VNX2 was announced, customers have asked me about using deduplication with their configs. I did an article on it around the time of the product announcement but have been meaning to talk a bit more about it for some time. But before I do, check out Joel Cason’sgreat post on this. Anyway, here’s a brief article listing some of the caveats and things to look out for with block deduplication. A few of my clients have used this feature in the field, and have learnt the hard way that if you don’t follow EMC’s guidelines, you may have a sub-optimal experience. Most of the information here has been taken from the “EMC VNX2 Deduplication and Compression” which can be downloaded here.
If you’re running a workload with more than 30% writes, compression and deduplication may be a problem. EMC state that, “[f]or applications requiring consistent and predictable performance, EMC recommends using Thick pool LUNs or Classic LUNs. If Thin LUN performance is not acceptable, then do not use Block Deduplication”. I can’t stress this enough – know your workload!
Block deduplication is done on a per pool LUN basis. EMC recommended that deduplication be enabled at the time of LUN creation. If you enable it on an existing LUN, the LUN is migrated into the deduplication container using a background process. The data must reside in the container before the deduplication process can run on the dataset.
There is only one deduplication container per storage pool. This is where your deduplicated data is stored. When a deduplication container is created, the SP owning the container needs to be determined. The container owner is matched to the Allocation Owner of the first deduplicated LUN within the pool. As a result of this process, EMC recommends that all LUNs with Block Deduplication enabled within the same pool should be owned by the same SP. This can be a big problem in smaller environments where you’ve only deployed one pool.
There’s a bit more to consider, particularly if you’re looking at leveraging compression as well. But if you can’t get past these first few considerations, it’s likely that the VNX2’s version of deduplication on primary storage is probably not for you. Read the whitepaper – it’s readily accessible and fairly clear about what can and can’t be achieved within the constraints of the product.
Many moons ago I wrote a brief article about accessing RemotelyAnywhere on the CX4. This was prompted by changes in Release 29 of FLARE that changed the access mechanism for remote console access on the SPs. I’ve been working on some VNX2s recently (or VNX with MCx – as EMC really would like them to be known), and I was curious as to whether the process was the same.
Pretty much, yep.
Nowadays there are a few ways to access RemotelyAnywhere on the VNX SP. There are a few different ports on the array that can be used, depending on your circumstances. In some environments, where you’re not allowed to touch the customer’s network with your own gear, the service port may be more appropriate. Here’s an image of the ports from EMC. The model of VNX you’re using will dictate the layout of the ports.
You can go via:
the SP’s management port: http://<SP IP address>:9519;
the SP’s service port: https://126.96.36.199:9519 (SP A) or https://188.8.131.52:9519 (SP B); and
the SP’s serial port: https://192.168.1.1:9519 (this assumes you’re connected via serial already – more on that below).
This is fairly straightforward, and you’ll need to be on a network that has access to the management ports.
So, you’re probably already aware that the best way to connect to the service port is to set your laptop TCP/IP settings as follows:
IP Address – 184.108.40.206 or 220.127.116.11
Subnet Mask – 255.255.255.248
Default Gateway – leave blank
DNS server entries – leave blank
If you want to connect via the serial cable, you’ll need to setup a PPP connection on your laptop. The following steps assume that you’ve got a USB to serial adapter and you’re using a Windows 7 machine.
Right Click on your Computer icon and Select Manage
Click on Device Manager
Expand Ports (COM & LPT)
Look for the USB-to-Serial Comm Port (COM##)
The COMM number will be the one you will select during the configuration of your PPP connection.
Create the COM Port
Click Start -> Control Panel -> Phone and Modem.
Click the “modem tab” and click Add.
On the Install new Modem Pane, select the Don’t detect my modem box, then click Next.
Select Communications cable between two computers, then click Next.
Select the COM port from the previous step, then click Next.
Highlight the new modem and click Properties.
Select the “modem tab” and adjust the max speed to 115200 then click OK.
Click OK again to exit the Phone and Modem screen.
In the Computer Management window, disable and then re-enable the USB Serial connection in Device Manager. Do this by right-clicking on it.
Setting Up the PPP Connection
Click Start -> Control Panel -> Network and Sharing Center, click Set up a new connection or network (at the bottom).
Click Next, select Set up a dial-up connection and click Next.
This screen should list modems and select the Communications cable between two computers created above.
On the next screen put in a random phone number. This is required in order to complete this step. You need at least one digit, but you’ll remove it later. Next put in the username and password and give it a name. Then click on Connect. This connection will fail displaying: Connection Failed with error 777. Click on Set up the connection anyway.
You will get: “The connection to the Internet is ready to use”. Select Close.
The above connection should now appear in Network Connections. Open Control Panel and select Change Adapter Settings.
Right-click on your new Modem connection and select Cancel as Default Connection.
Right Click on your new Modem connection again and select Properties.
Modify the Settings
In the General tab, remove the phone number entry and leave it blank.
In the General tab, click configure and set Max speed to 115200 and select enable hardware flow control.
In the Options tab, click PPP settings and check that the top two boxes are selected (LCP extensions and SW compression).
In the Security tab, check Data Encryption is Optional Encryption (connect even if no encryption) is set.
In the Networking tab, check Internet Protocol Version 4 is selected and click on Properties.
In the Networking tab, choose Internet Protocol Properties, then the Advanced button. Uncheck Use default gateway on remote network.
Here’s what it looks like when you log in – enjoy.