Thursday, June 27, 2013

New Server Form Factor: Cluster-in-a-Box

Traditional server clustering has always been one of the main 'bottlenecks' and complaints for most IT project roll-outs. The most common excuses from server admins: too complex, too expensive, taking too much power, rack space, air-con and the list goes on. To address these issues, there is a new breed of servers - not 1U or 2U rack mountable server and monstrous server blade - it's "Cluster-in-a-Box" or CiB in short. 

Simply put, all server clustering components, including computing, storage, clustering software and network, are pre-fabricated and pre-installed in a single box when deliver to your data centers. You don't have to worry about what kind of detailed specifications that you should put in your procurement tenders. Most importantly, most products claim to save power, cooling, and rack space. Take Nutanix for example. It claims to do away with expensive SAN storage and simplify cluster setup in 30 min. Furthermore, a 4-node cluster in a 2U rack mountable chassis. Compare Nutanix 1450 against traditional server clustering, the Dell equivalent would look something like:
  1. 4 x Dell R610 servers
    • 2 x Intel 6-core Xeon E5-2620
    • 64GB RAM
    • 400GB SSD
    • 2 x GE and 2 x 10GE
    • 2 x HBA controllers
  2. 2 x FC SAN switches
  3. 1 x FC SAN storage 
    • 16 x 1 TB SATA HDD
Adding up all components would take up about 8U of rack spaces with 7 different boxes or about 400% in saving in rack spaces against a single 2U Nutanix box.

Of course, traditional server vendors are not sitting back. Now, we are seeing new server product offerings like:
Look like we are entering the next wave of data center revolution.

Saturday, June 1, 2013

Does DELL MD32xx support hardware VSS snapshot for DPM Backup?

Answer: Yes, but it's not official. It's best effort (due to its low cost as compared to its high cost Compellent counterpart).

Hardware VSS snapshot provides an efficient way for DPM to backup Cluster Shared Volumes (CSVs) on Hyper-V cluster. Without hardware assisted snapshot, the CSV access would be placed under Redirect I/O mode as long as the backup process is taking place (which can be a long process). This can significantly reduce the I/O performance for other VMs on the same LUN. That's why it's more efficient to keep as small number of VMs per CSV as possible for software VSS. With hardware assisted VSS, a temporary snapshot is instead created on the free space on the SAN volume. CSV would only be placed on Redirect mode for a couple of minutes.

Screenshot of VSS Hardware Snapshot (new virtual disk temporarily created denoted with a clock icon) on MD Storage Manager during DPM backup:

How do we configure VSS setting on Dell MD storage?

Step 1: Install the VSS provider given on the Dell MD Storage Manager DVD or ISO image.

Step 2: Confirm Dell hardware VSS provider is installed on the system
C:\> vssadmin list providers
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2012 Microsoft Corp.

Provider name: 'SmVssProvider'
   Provider type: Hardware
   Provider Id: {24e4e8a3-69cb-4370-8b7b-c5276cd49765}
   Version: 10.84.02

Step 3: Configure the default VSS behavior on the storage as shown below. Run "C:\Program Files (x86)\Dell\SMprovider\provider\SmRegTool.exe" on the console installed with Dell Storage Manager. Connect to the storage using OOB Management IP addresses.