Tag Archives: Storage

Implementing your own corporate drop box ?

Upon perusing the Intel Cloud Builders site for interesting new cloudy vendors and reference architectures, I came across an interesting new company called Oxygen Cloud.  Although Storage as a Service is a reasonably well formed concept, much of the attention has been around public provider services such as livedrive, drop box or backup with products such as EMC Mozy. This is all well and good, but a number of companies have concerns over how the “public cloud” type products align to corporate policy. Take drop box for example, the ease of how data is shared or migrated across to other devices maybe doesn’t align to how they want to control one of an organisations most valuable commodities.. data.

So how does an organisation offer device agnostic storage, not based on the contraints of conventional file systems, in such a fashion where they maintain control ? Ultimately there are 101 ways to skin a cat… but as far as skinning cats goes, I quite like this one.

The Back End

You take a product like EMC Atmos; EMC Atmos is what we call cloud optimised storage. In real terms this means the way data is stored, how available it is, how its tiered across different costed storage and where it is stored geographically is handled by repeatable policy, not only this, but also meta data is leveraged to the nth degree (beyond that of traditional metadata uses in traditional file system). I won’t re-invent the explanation as EMC has done a good job of explaining this concept with pretty pictures (video below).

Atmos itself has a fair amount to it, but my point being  is that this use of metadata means that not only can the way data is handled be derived from this meta data, but now the infrastructure can have some awareness the context of data, context which is relevant to a front end such as Oxygen Cloud. Yes Atmos can deliver storage with NFS or CIFS, this is fine, but not overly exciting. The cool part is giving a front end direct access to the context of a file or a set of files using REST, rather than just last modified date and all the usual stuff. The metatags can be used to define the segregation of data in a muti-tenant environment or application specific elements, such as how a file can be shared and with whom.

Also, with Atmos being scale out storage the upper limits of scalability or need is say endless ? (or as near as), with the beauty of the storage being content addressable and not based around hierarchal file systems meaning that as the system is grown, you are not constrained and challenged by overly complex file system structures which need to be maintained.

Clearly availability is important, but hey..  this is expected. Needless to say, the system handles it very well.

The Front End

I’m not going to spend a great deal of time upping my word count on this section, as Oxygen Cloud have some very descriptive videos (further down), but the key things here are that the company controls the data in their own way. We have LDAP/AD integration, full access controls, we can set expiration of a link if we do share a file publicly, encryption at all point of a files transit and file can be presented as a normal explorer/finder plugin (same way we view normal CIFS shares) or files can be accessed via devices such as iPhone/Pad.  One nice feature for me is that if a phone is stolen or an employ leaves, the organisation can sever access to data/directories on a per user or device basis.

Anyway, worth spending a bit of time watching the below :

I shall be building this solution out on the lab over the next month or so (as much as the day job allows), so watch this space for more info and a revised review.

Sizing for FAST performance

So EMC Launched the VNX and changed elements of how we size for IO. We still have the traditional approach to sizing for IO in that we take our LUN’s and size for traditional RAID Groups. So lets start here first to refresh :

Everything starts with the application. So what kind of load is the application going to put on the disks of our nice shiny storage array ?

So lets say we have run perfmon or a similar tool to identify the number of disk transfers (IOPS)  occurring on a logical volume for an application. So we are sizing for a SQL DB volume which is generating 1000 IOPS for the sake of argument.

Before we get into the grit of the math. We must then decide what RAID time we want to use (as below are most common for transactional elements).

RAID 5 = Distributed parity, has a reasonably high write penalty, good usable vs raw capacity rating (equivalent of one drives usable capacity for parity) , a fair few people use this to get most bang for their buck. bear in mind that RAID 5 can suffer single drive failure (which will incur performance degradation), but will not protect from double disk failure. EMC Clariion does employ the use of hotspares, which can be proactively built when the Clariion detects a failing drive and used to substitute the failing drive when built, although if no hotspare exists or if a second drive fails during a drive rebuild or hotspare being build, you will lose your data. write penalty = 4

RAID 1/0 = Mirrored/Striped, lesser write penalty, more costly per GB as you lose 50% usable capacity to mirroring. RAID 1/0 provides better fault resilience and “rebuild” performance than RAID-5. It has better overall performance by combining the speed of RAID-0 with the redundancy of RAID-1 without requiring parity calculations. write penalty = 2

Yes there are only 2 RAID types here, but this is more to keep the concept simple.

So, depending on the RAID type we use, as certain write penalty is incurred due to mirroring or Parity operations.

Lets take a view on the bigger piece now. Our application Generates 1000 IOPS. We need to separate this into Reads and Writes :

So lets say. 20% writes Vs 80% reads. We then multiply the number of writes by the appropriate write penalty (2 for RAID 10 or 4 for RAID 5). Lets say RAID 5 is our selection :

The math is as follows :

800 Reads + (200 Writes x 4) = 1600 IOPS. This is the actual disk load we need to support.

We then divide that disk load by the IO Rating of the drive we wish to use. Generally speaking at a 4KB block size the below IO Ratings apply (this goes down as block sizes/pages to disk sizes get bigger).

15K SAS/FC = 180 IOPS
10k SAS/FC – 150 IOPS

The figure we are left with after dividing the disk load by the IO Rating is the number of spindles required. This is the same when sizing for sequential disk load, but we refer to MB/s and bandwidth instead of disk transfers (IOPS). Avoid using EFD for sequential data (overkill and not much benefit).

15k SAS/FC = 42 MB/s
10k SAS/FC = 35 MB/s
7.2k NLSAS – 25 MB/s

Bear in mind this does not take array cache into account and sequential writes to disk benefit massively from Cache, to the point where many papers suggest that NLSAS/SATA give comparable results to FC/SAS.

So What about FAST ?

Fast is slightly different. It Allows us to define Tier 0, Tier 1 and Tier 2 layers of disk. Tier 0 might be EFD, Tier 1 might be 15k SAS and Tier 2 might be NLSAS. When can have multiple tiers of disk residing in a common pool of storage (kind of like a raid group, but allowing for functions such as thin provisioning and tiering).

When can then create a LUN in this pool and specify that we want the LUN to start life on any given tier. As access patters to that LUN are analysed by the array over time, the LUN is split up into GB chunks and only the most active chunks utilise Tier 0 disk, the less active chunks are trickled down to our Tier 1 and Tier 2 disks in the pool.

fundamentally speaking, 90% of the IOPS for performance with the Tier 0 disk (EFD) and bulk out the capacity by splitting the remaining capacity between tier 1 and tier 2. You will find that in most cases you can service the IO with a fraction of the number of EFD disks vs if you did it all with SAS disks. I would suggest that if you know something should never require EFD such as B2D or archive data or Test/Dev, put them in a separate disk pool with no EFD.

EMC World 2011 – Las Vegas – day 1

So after the first day at EMC World what Marvels of technology have been announced ?
What groundbreaking nuggets of geeky goodness to be announced. So, first things first VPLEX ! looks like they may have cracked it..   Active/active storage over a synchronous distances, Geoclusters will never be the same again !!..   and also a slightly ambiguous announcement around integration with Hadoop opensource (more to follow on that).

What was the message of the day though ? What was this years theme..   This year EMC are talking about Big data and the cloud. Clearly recent acquisitions of Isilon and Greenplum have planted EMC’s head firmly back in the clouds.  Greenplum giving end users the ability to scale out Database architectures for data analytics to mammoth scale with Greenplums distributed node architecture and massive parallel processing capabilities. To br frank, learning about the technology was borderline mind numbing, but my god its a cool technology. Then we have large scale out NAS with Isilon and its OneFS system giving the ability to present massive NAS repositories and scale NAS on a large scale. So obviously, EMC are talking about big data.

I also had the opportunity to sit in on an NDA VNX/VNXe session and what they’re going to do is….    aaah, I’m not that stupid. But needless to say, there are some nice additions on the way, the usual thing with higher capacity smaller footprint drives and getting more IO in less U space, but also some very cool stuff on the way which will enable EMC to offer a much cheaper entry point for compliance ready storage..  watch this space.

In true style EMC threw out some interesting IDC touted metrics further justifying the need to drive storage efficiencies and re-iterating the fact that there will always be a market for storage. So, our digital universe consists of 1.2 Zettabytes of data, currently, of which 90% of that is unstructured data and that figure is predicted to grow by x44 over this decade. Also 88% of fortune 500 companies have to deal with Botnet attacks on a regular basis and have to contend with 60 Million Malware variants.  So making this relevant, the 3 main pain points of end users are; firstly our time old friend budget, then explosive data growth and securing data.

So how have EMC addressed these ? Well, budget is always a fun one to deal with, but with efficiencies in storage by way of deduplication, compression, thin provisioning and auto tiering of data, end users should get more bang for their buck. Also, EMC easing up on the rains with pricing around Avamar and the low entry point of VNXe, this should help the case. Dealing with explosive data growth again tackles with deduplication, compression, thin provisioning and auto tiering of data, but also now with more varied ways of dealing with large sums of data with technologies such as Atmos, greenplum, Isilon. Then the obvious aquisition of RSA to tie in with the security message, all be it that has had its challenges.

I’m also recently introduced the concept of a cloud architect certification track and the concept of a Data Scientist (god knows, but I’ll find out). So I went over to the proven professionals lounge and had a chat with the guys that developed the course. Essentially it gives a good foundation for steps to consider when architecting a companies private cloud, around Storage, virtualisation, networking and compute. If you’re expecting a consolidated course which covers the storage consolidate courseware, Cisco DCNI2, DCUCD course and VMware install configure manage,  then think again, but it does set a good scene as an overlay to understanding these technologies. It also delves into some concepts around cloud service change management and control considerations and the concept of a cloud maturity model (essentially EMM, but more cloud specific). I had a crack at the practice exam and passed with 68%, aside from not knowing the specific cloud maturity terms and EMC specific cloud management jargon anyone with knowledge of servers, Cisco Nexus and networking, plus virtualization shouldn’t have to many issues, but you may want to skim over the video training package.

There was also a nice shiny demo from the Virtual Geek Chad Sakkac showing the new Ionix UIM 2.1 with Vcloud integration using CSC’s cloud service to demonstrate not only the various subsets of multi tenancy, but also mobility between disparate systems. When they integrate with public cloud providers such as Amazon EC2 and Azure, then things will really hot up, but maybe we need some level of cloud standards in place ?…   but we all know the problem with standards, innovation gives way to bureaucracy and slows up…   but then again with recent cloud provider issues, maybe it couldn’t hurt to enforce a bit of policy which allows the market to slow up a little and take a more considered approach to the public cloud scenario..   who knows ?

Anyway.. watch this space..  more to come

Protocol considerations with VMware

A good video I came across from EMC discussing some storage protocol considerations when looking at VMware.

Adminstration of Clariion with VMWare… Getting easier

So, EMC released the NFS plugin for VMWare to support storage administration tasks on Celerra from the VI Client a while back, which was very cool and had some very impressive features..    but what about the Traditional SAN man ?! 

Well, yesterday EMC announced a VMWare plugin for Clariion.. 

Product Overview

The EMC CLARiiON Plug-in for VMware simplifies storage administration between the VMware Virtual Center Server and CLARiiON storage systems. It offers end-to-end management of storage related tasks including provisioning of datastores, provisioning of raw device mapping (RDM) devices, and array-based virtual machine replication.

New Feature Summary 

The EMC CLARiiON Plug-in for VMware allows you to perform the following specific tasks directly from the VMware vSphere client:

  • You can provision new datastores (VMFS volumes) or raw device mapping (RDM) volumes
  • Delete existing datastores backed by CLARiiON CX4 storage
  • Creation of virtual machine replicas using array-based replication services
  • The plug-in also gives you the option to publish the replicated virtual machines to a View Manager.


·       EMC CLARiiON Plug-in for VMware is customer-installable.

·       EMC CLARiiON Plug-in for VMware requires CX4 storage systems running Release 29 FLARE.

 Thats all I have at the minute, but will be picking the brain of the EMC bods as I go to get some more info.

Very usefull feature though !!

Iomega/EMC’s new lovechild

Iomega first started life selling removable storage. The world marvelled at the might of the 200MB Zip drive, brought gifts of  gold , frankincense and murr as offerings to the almighty Jazz drive and sacrificed livestock in awe of the the Ditto Drive  (I exagerate..  but bear with me, I’m setting the scene). Then, as removable storage media started to give way to internet and USB drives became the standard for removable storage..  we started to see the likes of the zip and jazz drive fade away.

So..  out with the old, in with the new ? No..  Now Iomega have a massive play in the consumer space for External Hard drives and networked storage. The upper end of the networked storage range was the IX4 (now on its second generation). A nice tidy box which would hold up to 8TB of RAW capacity and fit well in a remote office environment, home office, even as a media server for your movies and music (all legitimately obtained of course). They even did a rackmount NAS device..  Brilliant !!

But what if you need a little more grunt… a bit more redundancy, scalability.. something more feature rich. Iomega/EMC are on the verge of releasing the IX12. This box fits nice and snug between the IX4-200R and EMC’s Celerra NX4; it supports up to 24TB of RAW capacity, supports all the RAID types you’d ever want to use and has 4 Gigabit ports which can support up to 256 iSCSI initiators (servers) or 256 LUN’s for block level access. All the other usual protocols still apply in the oh so familiar forms of CIFS, NFS, FTP, HTTP, etc and there are even a few nice bells and whistles such as port aggregation, DFS, array based replication, WebDav Support for online collaboration and it also sports drive spin down (very cool if its being used for a backup to disk or archive target). 

The IX12 has also been certified by a number of other vendors; it is obviously certified and on VMwares Hardware compatibility List for shared storage (also supported by a number of other virtualization vendors). Microsoft have verified that it will support Exchange 2010 Mailstores for environments of up to 250 users.

Its being stated by Iomega that these boxes are sitting in at between $5,000 and $10,000 list,  so will help EMC break even further into the lower SMB market. Personally, I think this box will play really well in spaces such as remote office,  graphic design organisations, departmental dedicated storage, backup to disk targets (admittedly would be more compelling if it supported NDMP, but we’ll leave that to the big boys), archive storage for the likes of EMC’s SourceOne, EV, Commvault, etc…

I’ll put together a more clear and concise post after the announcements to come, but I think Iomega could be onto a winner on this one..

What is a SAN and how do I sell it ?

What is a SAN ? A SAN is a storage area network, with the sole purpose of providing dedicated storage to a server environment at block level. A SAN provides a central point of management for server storage, flexibility as to how that storage is managed and addresses the whole problem of under utilised pools of storage which you get when giving direct attached storage to servers on a one to one basis.


With the ever increasing interest in virtualisation technologies such as VMWare; virtualisation is driving more and more storage oppurtunities, as centralised storage is a must have requirement for functionalities such as High Availability and VMWare features such as VMotion and the likes.


So, you’ve established an oppurtunity; mr customer tells you they want to buy a SAN, what next ?

First things first, why do they want a SAN ? Typical reasons would be: they have direct attached storage for each server and its a nightmare to manage, they’re implementing or have implemented a virtualisation technology and need a SAN to unlock features around high availability, load balancing etc, they have an old SAN which is obsolete and simply won’t scale to the capacity or performance they need or our favourite, they bought a SAN based on a price driver only and their IT systems are suffering !

So the first exercise is something of a data gathering excersize and really you need to ween the following information :

The Data

What type of data will they be storing (file data/application data) ?

What applications will they be giving storage to ?

Performance requirements of these applications (based on perfmon/IO stat figures if possible).

Remember that different types of drives have different performance ratings. SATA drives being higher density lower performance drives are suited for the sequention type data (ie, file data, Backup to disk, archive, streaming).

Applications which will be accessing storage with data of a more random profile (ie, SQL, exchange, oracle, database in general) will usually require something with a bit more grunt, such as fibre channel or SAS drives which typically come in 10k RPM and 15K RPM flavours.

The rule of thumb being more drives = more performance (there is a science to this, so understanding the applications is key). Sometimes a good indicator would be to look at a given server and the number of drives (DAS) its using, if its performing as it should, then ensure it has drives which will give => IOPs in the SAN to meet its perfomance requirements in the SAN. Also, trying and keep data of a senquetial profile on seperate disks from data of a random type profile.

What is the current Capacity requirement ? and what is the expected growth over 3 years ?

How many LUNs (volumes) will be required for the customer environment ?


Do they want to utilise their existing infrastructure and use iSCSI or have a dedicated storage area network using fibre channel.

How many servers will be attaching to the SAN ?

What kind of IOP/Bandwidth load will each server be putting on the storage network ?

Most customers will want to have a redundant infrastructure so make sure you eliminate single points of failure from the environment. This means ideally 2 NICs or HBA’s per server, 2 switches, failover/multipathing software, etc.  So with this in mind make sure that you size the number of ports required on fibre/layer 2 switches accordningly (taking into account ISL’s).


In the spirit of minimising risk within a customer environment, customers are looking to local and remote replication technologies to do this.

Local recovery would be achieved by taking a point in time or fully copy of a given volume within the storage array, so if data is corrupted, as previous non corrupt version of the data from a prior point in time can be utlised.

If doing this then ensure the appriopriate capacity is accounted for on the storage array :

If using clones, then how ever many clones are being used will require the full capacity of the source volumes they are associated with. If Snapshots are being used, then each point in time ideally requires 2 x the amount on changed data of the source volume during the life of the point in time copy. Normally point in time copies would only exist for a number of hours until the next point in time image is taken. Its advised that volumes used for snapshotting reside on seperate drives to their respective source volumes as there is an IO overhead involved in snapshotting.

Remote Replication

If the customer wants to implement a remote DR solution, sometimes customer expectations of what is achievable within a given price bracket is slightly out of line with reality. So its important to sit with the customer and discuss things like:

  • How much data can I afford to lose before my business is adversley effected (RPO – Recovery Point Obective)


  • How much time can I allow for this volume/application to be offline before it becomes unacceptable (RTO – Recovery Time Objective)

The smaller the RTO and RPO, the greater the cost to the customer.

If the customer want to replicate at array level, using something like EMC’s Mirrorview/Syncronous product for example. These are the considerations.

Application response time on critial applications is always going to be the key consideration. If replicating syncronously, the write from the application is sent to the storage array and before a write acknowledgement is sent back to the application, the write must have commited to disk on both local and remote storage systems. If the response time requiment is around 5 ms, then that write needs to have written to have travelled the Link, committed to disk, acknowledge that write back to the production storage and then written to disk on production disk within 5ms, this means fast spinny disks and a very good link. If this is not sized properly, application will time out and Database admins will scream bloody murder.

Volumes which may not require such an agressive RPO, a-syncronous replication may be the way forward. So lets take a look at EMC’s Mirrorview/A-Syncronous product.


Firstly, the source volume is syncronised in its entirety with its respective opposite volume on the DR site. After this has syncronisation has taken place, then mirroriew will take point in time images of the source volume at specified intervals and replicate only delta changes to the remote site. The benefit of this would be that the application recievs acknowledgement of a write once its been written to disk and is not dependant upon the whole replication process.

There are some other methods, such as Continuous data protection (journalling) and other methods which ensure application transactional consistency, but I will come back to those on another post.