Category Archives: CIFS

Enhancing NAS client resiliency and performance with SMB Multichannel and NFS nconnect

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NAS (network attached storage) is obviously the file-level workhorse for shared resources in the network of any organization. SMB (server message block) for Windows environments and NFS (network file system) for Linux platforms are the 2 most prominent protocols that rule the NAS world. Of course we have SMB implementations in the form of Samba and others in non-Windows, Linux and NFS implementations in Windows as well.

As the versions of both network file sharing protocols iterated, present versions of SMB v3.x and NFS v4.x (NFS v3 on the supported Linux kernel version) on the client-side have evolved well. Both now have enhanced resiliency and performance improvement features. And there is an underlying similarity of both implementations. This blog looks at the client-side architectures of both.

One TCP connection

NAS is a client-server architecture. Over the network, NAS clients (SMB or NFS) access their corresponding NAS server(s) – SMB or NFS server(s) – through the TCP/IP network.

NAS client-server architecture (Credit: https://hypertecsp.com/en-CA/knowledge-base/nas-vs-san/)

One very important key starting point to note is the use of one TCP connection per NAS client to the NAS server relationship. For both SMB and NFS, there is just one TCP link between client and the server even if there are several SMB mapped shares or NFS mount points respectively on the clients.

For a long time, this one TCP connection is sufficient for the NAS traffic. But as the network file accesses grow, this connection becomes both a single point of failure as well as a performance bottleneck.

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Understanding security practices in File Synchronization

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Ho hum. Another day, and another data leak. What else is new?

The latest hullabaloo in my radar was from one of Malaysia’s reverent universities, UiTM, which reported a data leak of 11,891 student applicants’ private details including MyKad (national identity card) numbers of each individual. Reading from the news article, one can deduced that the unsecured link mentioned was probably from a cloud storage service, i.e. file synchronization software such as OneDrive, Google Drive, Dropbox, etc. Those files that can be easily shared via an HTTP/S URL link. Ah, convenience over the data security best practices. 

Cloud File Sync software

It irks me when data security practices are poorly practised. And it is likely that there is ignorance of data security practices in the first place.

It also irks me when many end users everywhere I have encountered tell me their file synchronization software is backup. That is just a very poor excuse of a data protection strategy, if any, especially in enterprise and cloud environments. Convenience, set-and-forget mentality. Out of sight. Out of mind. Right? 

Convenience is not data security. File Sync is NOT Backup

Many users are used to the convenience of file synchronization. The proliferation of cloud storage services with free Gigabytes here and there have created an IT segment based on BYOD, which transformed into EFSS, and now CCP. The buzzword salad involves the Bring-Your-Own-Device, which evolved into Enterprise-File-Sync-&-Share, and in these later years, Content-Collaboration-Platform.

All these are fine and good. The data industry is growing up, and many are leveraging the power of file synchronization technologies, be it on on-premises and from cloud storage services. Organizations, large and small, are able to use these file synchronization platforms to enhance their businesses and digitally transforming their operational efficiencies and practices. But what is sorely missing in embracing the convenience and simplicity is the much ignored cybersecurity housekeeping practices that should be keeping our files and data safe.

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TrueNAS SCALE Clustered SMB to the fore

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iXsystems™ released second iteration of TrueNAS® SCALE software just over a week ago. It is known as version 22.02.2 or Anglefish.2, with the most notable upgrades to HA (High Availability) for SCALE and Clustered SMB capabilities. This is the perfect excuse for me to learn about Clustered SMB and share what I have learned.

TrueNAS SCALEFor the

For the uninformed, Clustered SMB brings highly available SMB file sharing services to mission critical environments. More importantly, Clustered SMB is high availability in a scale-out clustered architecture.

My view beyond HA SMB

I am not familiar with Clustered SMB in a NAS (Network Attached Storage). The world I am more familiar with is either having CIFS/SMB file services on a dual controller storage appliance or running Windows File Sharing on an Microsoft® Clustered Service (MSCS). Typically in these 2 types of HA SMB services, the scale up architecture require a shared access to a consolidated storage volume. Behind the scenes, there are many mechanisms at play to ensure that one, and only one, storage controller or HA host can have write access capabilities at one time. The most common mechanism is the SCSI-3 Persistent Reservation or sometimes known as SCSI fencing, using the SPC-3 (SCSI Primary Command) primitives. The whole objective is to prevent 2 nodes or hosts to writing to the shared storage volume at the same time and other issues like split-brain.

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Stating the case for a Storage Appliance approach

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I was in Indonesia last week to meet with iXsystems™‘ partner PT Maha Data Solusi. I had the wonderful opportunity to meet with many people there and one interesting and often-replayed question arose. Why aren’t iX doing software-defined-storage (SDS)? It was a very obvious and deliberate question.

After all, iX is already providing the free use of the open source TrueNAS® CORE software that runs on many x86 systems as an SDS solution and yet commercially, iX sell the TrueNAS® storage appliances.

This argument between a storage appliance model and a storage storage only model has been debated for more than a decade, and it does come into my conversations on and off. I finally want to address this here, with my own views and opinions. And I want to inform that I am open to both models, because as a storage consultant, both have their pros and cons, advantages and disadvantages. Up front I gravitate to the storage appliance model, and here’s why.

My story of the storage appliance begins …

Back in the 90s, most of my work was on Fibre Channel and NFS. iSCSI has not existed yet (iSCSI was ratified in 2003). It was almost exclusively on the Sun Microsystems® enterprise storage with Sun’s software resell of the Veritas® software suite that included the Sun Volume Manager (VxVM), Veritas® Filesystem (VxFS), Veritas® Replication (VxVR) and Veritas® Cluster Server (VCS). I didn’t do much Veritas® NetBackup (NBU) although I was trained at Veritas® in Boston in July 1997 (I remembered that 2 weeks’ trip fondly). It was just over 2 months after Veritas® acquired OpenVision. Backup Plus was the NetBackup.

Between 1998-1999, I spent a lot of time working Sun NFS servers. The prevalent networking speed at that time was 100Mbits/sec. And I remember having this argument with a Sun partner engineer by the name of Wong Teck Seng. Teck Seng was an inquisitive fella (still is) and he was raving about this purpose-built NFS server he knew about and he shared his experience with me. I detracted him, brushing aside his always-on tech orgasm, and did not find great things about a NAS storage appliance. Auspex™ was big then, and I knew of them.

I joined NetApp® as Malaysia’s employee #2. It was an odd few months working with a storage appliance but after a couple of months, I started to understand and appreciate the philosophy. The storage Appliance Model made sense to me, even through these days.

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As Disk Drive capacity gets larger (and larger), the resilient Filesystem matters

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I just got home from the wonderful iXsystems™ Sales Summit in Knoxville, Tennessee. The key highlight was to christian the opening of iXsystems™ Maryville facility, the key operations center that will house iX engineering, support and part of marketing as well. News of this can be found here.

iX datacenter in the new Maryville facility

Western Digital® has always been a big advocate of iX, and at the Summit, they shared their hard disk drives HDD, solid state drives SSD, and other storage platforms roadmaps. I felt like a kid a candy store because I love all these excitements in the disk drive industry. Who says HDDs are going to be usurped by SSDs?

Several other disk drive manufacturers, including Western Digital®, have announced larger capacity drives. Here are some news of each vendor in recent months

Other than the AFR (annualized failure rates) numbers published by Backblaze every quarter, the Capacity factor has always been a measurement of high interest in the storage industry.

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Unstructured Data Observability with Datadobi StorageMAP

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Let’s face it. Data is bursting through its storage seams. And every organization now is storing too much data that they don’t know they have.

By 2025, IDC predicts that 80% the world’s data will be unstructured. IDC‘s report Global Datasphere Forecast 2021-2025 will see the global data creation and replication capacity expand to 181 zettabytes, an unfathomable figure. Organizations are inundated. They struggle with data growth, with little understanding of what data they have, where the data is residing, what to do with the data, and how to manage the voluminous data deluge.

The simple knee-jerk action is to store it in cloud object storage where the price of storage is $0.0000xxx/GB/month. But many IT departments in these organizations often overlook the fact that that the data they have parked in the cloud require movement between the cloud and on-premises. I have been involved in numerous discussions where the customers realized that they moved the data in the cloud moved too frequently. Often it was an erred judgement or short term blindness (blinded by the cheap storage costs no doubt), further exacerbated by the pandemic. These oversights have resulted in expensive and painful monthly API calls and egress fees. Welcome to reality. Suddenly the cheap cloud storage doesn’t sound so cheap after all.

The same can said about storing non-active unstructured data on primary storage. Many organizations have not been disciplined to practise good data management. The primary Tier 1 storage becomes bloated over time, grinding sluggishly as the data capacity grows. I/O processing becomes painfully slow and backup takes longer and longer. Sounds familiar?

The A in ABC

I brought up the ABC mantra a few blogs ago. A is for Archive First. It is part of my data protection consulting practice conversation repertoire, and I use it often to advise IT organizations to be smart with their data management. Before archiving (some folks like to call it tiering, but I am not going down that argument today), we must know what to archive. We cannot blindly send all sorts of junk data to the secondary or tertiary storage premises. If we do that, it is akin to digging another hole to fill up the first hole.

We must know which unstructured data to move replicate or sync from the Tier 1 storage to a second (or third) less taxing storage premises. We must be able to see this data, observe its behaviour over time, and decide the best data management practice to apply to this data. Take note that I said best data management practice and not best storage location in the previous sentence. There has to be a clear distinction that a data management strategy is more prudent than to a “best” storage premises. The reason is many organizations are ignorantly thinking the best storage location (the thought of the “cheapest” always seems to creep up) is a good strategy while ignoring the fact that data is like water. It moves from premises to premises, from on-prem to cloud, cloud to other cloud. Data mobility is a variable in data management.

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I built a 6-node Gluster cluster with TrueNAS SCALE

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I haven’t had hands-on with Gluster for over a decade. My last blog about Gluster was in 2011, right after I did a proof-of-concept for the now defunct, Jaring, Malaysia’s first ISP (Internet Service Provider). But I followed Gluster’s development on and off, until I found out that Gluster was a feature in then upcoming TrueNAS® SCALE. That was almost 2 years ago, just before I accepted to offer to join iXsystems™, my present employer.

The eagerness to test drive Gluster (again) on TrueNAS® SCALE has always been there but I waited for SCALE to become GA. GA finally came on February 22, 2022. My plans for the test rig was laid out, and in the past few weeks, I have been diligently re-learning and putting up the scope to built a 6-node Gluster clustered storage with TrueNAS® SCALE VMs on Virtualbox®.

Gluster on OpenZFS with TrueNAS SCALE

Before we continue, I must warn that this is not pretty. I have limited computing resources in my homelab, but Gluster worked beautifully once I ironed out the inefficiencies. Secondly, this is not a performance test as well, for obvious reasons. So, this is the annals along with the trials and tribulations of my 6-node Gluster cluster test rig on TrueNAS® SCALE.

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Crash consistent data recovery for ZFS volumes

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While TrueNAS® CORE and TrueNAS® Enterprise are more well known for its NAS (network attached storage) prowess, many organizations are also confidently placing their enterprise applications such as hypervisors and databases on TrueNAS® via SANs (storage area networks) as well. Both iSCSI and Fibre Channel™ (selected TrueNAS® Enterprise storage models) protocols are supported well.

To reliably protect these block-based applications via the SAN protocols, ZFS snapshot is the key technology that can be dependent upon to restore the enterprise applications quickly. However, there are still some confusions when it comes to the state of recovery from the ZFS snapshots. On that matter, this situations are not unique to the ZFS environments because as with many other storage technologies, the confusion often stem from the (mis)understanding of the consistency state of the data in the backups and in the snapshots.

Crash Consistency vs Application Consistency

To dispel this misunderstanding, we must first begin with the understanding of a generic filesystem agnostic snapshot. It is a point-in-time copy, just like a data copy on the tape or in the disks or in the cloud backup. It is a complete image of the data and the state of the data at the storage layer at the time the storage snapshot was taken. This means that the data and metadata in this snapshot copy/version has a consistent state at that point in time. This state is frozen for this particular snapshot version, and therefore it is often labeled as “crash consistent“.

In the event of a subsystem (application, compute, storage, rack, site, etc) failure or a power loss, data recovery can be initiated using the last known “crash consistent” state, i.e. restoring from the last good backup or snapshot copy. Depending on applications, operating systems, hypervisors, filesystems and the subsystems (journals, transaction logs, protocol resiliency primitives etc) that are aligned with them, some workloads will just continue from where it stopped. It may already have some recovery mechanisms or these workloads can accept data loss without data corruption and inconsistencies.

Some applications, especially databases, are more sensitive to data and state consistencies. That is because of how these applications are designed. Take for instance, the Oracle® database. When an Oracle® database instance is online, there is an SGA (system global area) which handles all the running mechanics of the database. SGA exists in the memory of the compute along with transaction logs, tablespaces, and open files that represent the Oracle® database instance. From time to time, often measured in seconds, the state of the Oracle® instance and the data it is processing have to be synched to non-volatile, persistent storage. This commit is important to ensure the integrity of the data at all times.

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What happened to NDMP?

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The acronym NDMP shows up once in a while in NAS (Network Attached Storage) upgrade tenders. And for the less informed, NDMP (Network Data Management Protocol) was one of the early NAS data management (more like data mover specifications) initiatives to backup NAS devices, especially the NAS appliances that run proprietary operating systems code.

NDMP Logo

Backup software vendors often have agents developed specifically for an operating system or an operating environment. But back in the mid-1990s, 2000s, the internal file structures of these proprietary vendors were less exposed, making it harder for backup vendors to develop agents for them. Furthermore, there was a need to simplify the data movements of NAS files between backup servers and the NAS as a client, to the media servers and eventually to the tape or disk targets. The dominant network at the time ran at 100Mbits/sec.

To overcome this, Network Appliance® and PDC Solutions/Legato® developed the NDMP protocol, allowing proprietary NAS devices to run a standardized client-server architecture with the NDMP server daemon in the NAS and the backup service running as an NDMP client. Here is a simplified look at the NDMP architecture.

NDMP Client-Server Architecture

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Windows SMB synchronous writes with OpenZFS

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Sometimes I get really pissed off with myself because I have taken a bigoted view, and ended up with eggs on my face. The past week was like that, and the problem was gnawing me on the inside all week, because I was determined to balance my equilibrium by finding the answer.

Early in the week, I was having a conversation with a potential customer. It evolved around the missing 10 seconds or so of the video footage between the users of a popular video editing software. The company had 70% Windows users, and 30% users on the Mac, both sides accessing the NAS device. The issue was the editors on the Windows side will store the raw and edited files to the NAS, but when the Mac users read them, they will often find 10 seconds or so of the stored video files missing.

The likeliest culprit of this problem is the way the SMB protocol write I/O behaves in Windows and in MacOS. Windows SMB, by default, writes I/O asynchronously while SMB on MacOS writes I/O synchronously.

I had a strong conviction I had the answer to this issue but this was not a TrueNAS®, It was another brand of NAS that I did not have knowledge of, and so, I left the conversation feeling quite embarrassed because I had the answer only on the TrueNAS® server side, not on the Windows client side. Bigotry blinded me. Hmmph! 

SMB (Server Message Block) client-server model

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