Comment by timurlenk | Hacker News Reader

Comment by timurlenk | Hacker News Reader

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I was wondering about what you guys think of NAS systems.

While I don't claim to fully understand the advantages brought by block storage vs. file based storage, NAS storage should be usable for most applications. If this is true than the clustered or scale out solutions offered by IBM (SONAS), HP (IBRIX) and EMC (with the recent acquisition of Isilon) might be a suitable off the shelf solution matching your scenario (probably there are some open source solutions also that I am not aware of).

The way I understand these solutions you can basically scale capacity and performance independently which in turn translates itself in the flexibility of achieving the ideal balance between capacity and failure point distribution/redundancy.

What do you guys think of this setup? Would it achieve your goals?

I'm coming from a corporate environment where having an off the shelf solution that is supported by some major company is as important as the solution itself.

The difference between NFS and iSCSI should be fairly small at this point. Anything by IBM, HP, or EMC will cost at least 10x as much as local disk, which is death for most cloud providers. Unfortunately, stuff like DRBD or Sheepdog may be only 2x the cost of local disk but doesn't look ready for prime time.

Just to come back on the point regarding NFS versus iSCSI: - proprietary systems like IBM's, HP etc. are both expensive and complicated. This violates our 'simple problems' mantra as well as having cost implications. - our IaaS platform has an open software layer with sole root access granted to the user. That has huge security and privacy implications for our users i.e. they have access to their data, we as a vendor don't (except for physical access which is highly restricted and monitored). It means we see customer drives as block storage devices. We can't see their file systems. NFS can we implemented by a customer on top of our platform but not by ourselves. We do in fact have many users of NFS in our cloud. Its our job to manage the storage at the block device level. As a vendor we are a 'pure IaaS' provider. We don't reach into the software and networking layers wherever possible. Its a fundamentally different approach giving our customers the same sort of control over their computing as they would with a dedicated set-up. - DRBD has de-duplification. For a public cloud like ours this will save us a lot of space, more than the replication introduced. Why? We just RAID6 already so replication won't be higher with DRBD (we will swap RAID6 for DRBD). We have thousands of identical operating systems running concurrently with their own distinct copies (each of our cloud servers is a complete stand alone OS on its own block device, again for privacy/security reasons).

So, we believe that a move from our current set-up to distributed block storage will actually REDUCE costs overall no increase them. We will of course have the added convenience and elimination of single points of failure in storage that distributed block storage entails.

Best wishes,

Patrick CEO CloudSigma

I was thinking more of the VMware approach of storing disk images (e.g. VMDK files) on NFS; that's not much different than using iSCSI.

OK fair enough. Most public clouds don't use VMWare for cost reasons. It would be cheaper than some of the other commercial systems alluded to but still a significant cost compared with other virtualisation platforms. Its also using a proprietary format so you can't mix and match (whereas we are using RAW ISO files). Finally, you'll need VMWare qualified staff instead of regular sys admins. That's another incremental cost that isn't insignificant.

Best wishes,

Patrick

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