I was contacted last month by Eva Helen in Sanbolic to see if I’d be interested in learning more about their Melio FS product. I knew little about it and was keen to learn. So Eva got David Dupuis to give me a demo. Dave just ran an hour long demo on LiveMeeting with me and I learned a lot. I gotta say, I’m impressed with this solution.
There were two Sanbolic products that Dave focused on:
- La Scala = Cluster Volume Manager used instead of disk manager. It’s a shared volume manager. It is aware of what nodes are attached to it.
- Melio = Cluster File System.
- La Scala can mirror volumes across 2 SAN’s, allowing for total SAN failure. Each server has two controllers or a dual channel HBA, one path going to each SAN. 1 write is converted to two writes on two paths. In theory, there’s no noticeable performance hit for amazing fault tolerance.
- On the fly volume expansion
- Can use any block based shared storage iSCSI or fibre channel system
- You can set up a task, e.g. expand disk, and review it before committing the transaction.
- Windows ACL’s are integrated in the interface to control volume access rights.
I’ve got to say, the SAN mirroring is pretty amazing technology. Note the performance will equal the slowest SAN. It can take cheap storage solutions that might not even have controller/path fault tolerance and give them really high fault tolerance via redundant arrays and mirrored storage with an unperceivable performance hit due to the mirroring being done by simultaneous writes by 2 independent controller paths.
- This is 64-bit symmetrical cluster file system.
- There is no coordinator node, management server, metadata controller, etc, that manages the overall system. So there’s no redirected I/O mode *cheers from Hyper-V admins everywhere*
- Metadata is stored on the file system and every node in the cluster has equal access to this. This is contrary to the CSV coordinator in W2008 R2 failover clustering.
- QoS (quality of service) allows per process or per file/folder file system bandwidth guarantees. This allows granular management of SAN traffic for the controlled resources. In the Hyper-V context, you can guarantee certain VHD’s a percentage of the file system bandwidth. You can also use wildcards, e.g. *.VHD. This is another very nice feature.
- There is a VSS provider. This is similar to how SAN VSS providers would work. Unlike CSV, there is no need for redirected I/O mode when you snap/backup the LUN.
- There is a bundled product called SILM that allows you to copy (via VSS) new/modified files to a specified LUN on a scheduled basis.
- Backups solutions like BackupExec that recognise their VSS provider can use it to directly backup VM’s on the Melio file system.
- MS supports this system, i.e. Failover Clustering and VMM 2008 R2. For example, Live Migration uses the file system. You’ll see no CSV or storage in Failover Clustering. The Melio file system appears as a normal lettered drive on each node in the cluster.
- By using advance exclusive lock detection mechanisms that CSV doesn’t have, Melio can give near raw disk performance to VHD. They say they have faster (57%) VHD performance than CSV!
- You can provide iSCSI accessed Melio file systems to VM’s. You can license the product by host –> gives you 4 free VM licenses.
- Melio isn’t restricted to just Hyper-V: web servers, SQL, file servers, etc.
- Issues seen with things like AV on CSV aren’t likely here because there is no coordinator node. All metadata is available to all nodes through the file system. You need to be aware of scheduled scans: don’t have all nodes in the cluster doing redundant tasks. The tip here: put a high percentage guarantee for *.VHD and the AV has been controlled.
It’s got to be said that you cannot think of this as some messy bolt on. Sanbolic has a tight relationship with Microsoft. That’s why you see their Melio file system being listed as a supported feature in VMM 2008 R2. And that can only happen if it’s supported by Failover Clustering – VMM is pretty intolerant of unsupported configurations.
Overall, I’ve got to say that this is a solution I find quite interesting. I’d have to give it serious consideration if I was designing a cluster from scratch and the mirroring option raises some new design alternatives.
My $64,000,000 question has probably been heard by the guys a bunch of times but it got a laugh: “when will Microsoft buy Sanbolic and have you invested a lot in the company share scheme?”. Seriously though, you’d think this would be a quick and superb solution to get a powerful cluster file system that is way ahead of VMFS and more than “just” a virtualisation file system.
Thanks to the kind folks at Sanbolic for the demo. It’s much appreciated!