Storage Resolutions

The new year is here. Everyone loves to make resolutions to say how they are going to improve their lives. Personally I think it is nonsense; if you want to change, then you can do it any time rather than the abitrary time of new year.

Anyway, enough of my humbug. Here's a few storage resolutions I hope to maintain:

• iSCSI - I haven't paid enough attention to this. I think iSCSI is due to hit its tipping point this year and get much more widespread adoption.
• WAFS - Wide Area File Systems interest me. Any opportunity to reduce the volume of data being moved across networks while centralising the gold copy strikes me as a sensible idea.
• CDP - There are some interesting products around providing continuous data protection. They aren't scalable yet, but when they are I can see them being big.
• NAS Virtualisation - OK, I know how it works and what the products are; I just need to get into more detail.
• CAS - I've always seen CAS as pointless. It's time to give it a second chance.

So that's the technology side covered. What about process?

• ILM - I think it is time to harp on about proper ILM - i.e. that which is integrated into the application rather than the poor efforts we've seen to date. I think application development needs to be addressed to cover this.
• SRM - how about some proper tools which actually do the job of managing the (large scale) process of storage deployment? More thought required here.
• Cost Management - I believe there are lots of options for managing and reducing cost, I should expound on them more.
• Technology Refresh - Always a problem and certainly needs more thought for mature datacentres.

Hmm, funny how each year's resolutions end up sounding just like the ones the year before?

Netapp 1 EMC 0

My RSS reader just picked up a lovely report from Netapp countering an EMC report showing that with MS-Exchange workloads, EMC was better than Netapp (CX3-40 v 3050). It just shows how when vendors are challenged to defend their products, they can make them work much better than the "standard" configuration. I can't help thinking it would be better if these products did this without needing the vendor to do a lot of configuration work.

Original report here.... http://www.netapp.com/library/tr/3521.pdf

Understanding Statistics

I've been reading a few IDC press releases today. The most interesting (if any ever are) was that relating to Q3 2006 revenue figures for the top vendors. It goes like this:

Top 5 Vendors, Worldwide External Disk Storage Systems Factory Revenue 3Q2006 (millions)

EMC: $927 (21.4%)
HP: $760 (17.6%)
IBM: $591 (13.7%)
Dell: $347 (8.0%)
Hitachi: $340 (7.9%)

So EMC comes out on top, followed by the other usual suspects. EMC gained market share from all other vendors including "The Others" (makes me think of Lost - who are those "others"?). However, IDC also quote the following:

Top 5 Vendors, Worldwide Total Disk Storage Systems Factory Revenue 3Q2006 (millions)

HP: $1406 (22.7%)
IBM: $1250 (20.2%)
EMC: $927 (15.0%)
Dell: $507 (8.2%)
Hitachi: $348 (5.6%)

So what does this mean? IDC defines a Disk Storage System as at least 3 disk drives and the associated cables etc, to connect them to a server. This could mean 3 disks with a RAID controller in a server. Clearly EMC don't ship anything other than external disks as their figures are the same in each list. HP make only 50% of their disk revenue from external systems, the rest presumably are disks shipped with servers, IBM even less as a percentage, Dell about $160m. The intruiging one was Hitachi - what Disk Storage Systems to they sell (other than external) which made $8m of revenue? The source of my data can be found here: http://www.idc.com/getdoc.jsp?containerId=prUS20457106

What does this tell me? It says there's a hell of a lot of DAS/JBOD stuff still being shipped out there - about 30% of total revenue.

Now, if EMC were to buy Dell or the other way around, between them they could (just) pip HP to the post. Are EMC and Dell merging? I don't know, but I don't mind starting a rumour...

Oh, another intesting IDC article I found referred to how big storage virtualisation is about to come. I've been saying the word "virtualisation" for about 12 months in meetings just to get people to even listen to the concept, even when the meeting has nothing to do with the subject. I'm starting to feel vindicated.

Modular Storage Products

I’ve read a lot of posts recently on various storage related websites asking for comparisons of modular storage products. By that I’m referring to “dual controller architecture” products such as the HDS AMS, EMC Clariion and HP EVA. The questions come up time and time again, usually comparing IBM to EMC or HP and little comparison to HDS, but lots of people recommending HDS.

So, to be more objective, I’ve started compiling a features comparison of the various models from HDS, IBM, EMC and HP. Before anyone starts, I know there are other vendors out there – 3PAR, Pillar and others come to mind. At some stage, I’ll drag in some comparisons to them too, but to begin with this is simply the “big boys”. The spreadsheet attached is my first attempt. It has a few gaps where I couldn’t determine the comparable data, mainly on whether iSCSI or NAS is a supported option and the obvious problem of performance throughput.

So, from a simple physical perspective, these arrays are pretty simple to compare. EMC and HDS give the highest disk capacity options, EMC, HDS and IBM offer the same maximum levels of cache. Only HDS offers RAID6 (at the moment), most vendors offer a range of disk drives and speeds. Most products offer 4Gb/s front-end connections and there are various options for 2/4Gb/s speeds at the back end.

Choosing a vendor on physical specifications alone is simple using the spreadsheet. However there are plenty of other factors not included here. First, there’s performance. Only IBM (from what I can find) offers their arrays to scrutiny by the Storage Performance Council. Without a consistent testing method, any other figures offered by vendors are completely subjective.

Next, there’s the thorny subject of feature sets. All vendors offer variable LUN sizes, some kind of failover (I think most are active/passive), multiple O/S support, replication and remote copy functionality and so on. Comparing these isn’t simple, though as the implementation of what should be common features can vary widely.

Lastly there’s reliability and the bugs and gotchas that all products have and which the manufacturers don’t document. I’ll pick an example or two; do FC front-end ports share a multiprocessor? If so, what impact does load on one port have on the other shared port? What downtime is required to do maintenance, such as code upgrades? What is the level of SNMP or other management/alerting software?

The last set of issues would prove more difficult to track so I’m working on a consistent set of requirements from a product. In the meantime, I hope the spreadsheet is useful and if anyone can fill the gaps or wants to suggest other comparable mid-range/modular products, let me know.

You can download the spreadsheet here: http://www.storagewiki.com/attachments/modular%20products.xls

New RAID

Lots of people are talking about how we need a new way to protect our data and that RAID has had it. Agreed, going RAID6 gives some benefits (i.e. puts off the inevitable failure by a factor again), however the single problem to my mind with RAID today is the need to read all the other disks when a real failure occurs. Dave over at Netapp once calculated the risk of re-reading all those disks in terms of the chance of a hard failure.

The problem is, the drive is not involved in the rebuild process - it dumbly responds to the request from the controller to re-read all the data. What we need are more intelligent drives combined with more intelligent controllers; for example; why not have multiple interfaces to a single HDD? Use a hybrid drive with more onboard memory to cache reads while the heads are moving to obtain real data requests. Store that data in memory on the drive to be used for drive rebuilds. Secondly, why do we need to store all the data for all rebuilds across all drives? Why with a disk array of 16 drives can't we run multiple instances of 6+2 RAID across different sections of the drive?

I'd love to be the person who patents the next version of RAID....

How low can they go!

I love this picture. Toshiba announced today that they are producing a new 1.8" disk drive using perpendicular recording techniques. This drive has a capacity of 100GB!

It will be used on portable devices such as music players; its only 54 x 71 x 8 mm in size, weighs 59g and can transfer data at 100MB/s using an ATA interface.

I thought I'd compare this to some technology I used to use many years ago - the 3380 disk drive.

The model shown on the right is the 3380 CJ2 with a massive 1.26GB per unit and an access time similar to the Toshiba device. However the transfer rate was only about 3MB/s.

I couldn't find any dimensions for the 3380, but from the picture of the lovely lady, I'd estimate it is 1700 x 850 x 500mm which means 23,500 of the Tosh drives could fit in the same space!

Where will we be in the next 20 years? I suspect we'll see more hybrid drives, with NAND memory used to increase HDD cache then more pure NAND drives (there are already some 32GB drives announced). Exciting times...

Is the Revolution Over?

I noticed over the weekend that http://www.storagerevolution.com's website was down. Well it's back up today, but the forums have disappeared. I wonder, is the revolution over for JWT and pals?

A rival to iSCSI?

I've said before, somethings just pass you by, and so it has been with me and Coraid. This company uses ATA-over-Ethernet, a lightweight IP storage protocol to connect hosts to their storage products.

It took me a while before I realised how good this protocol could be. Currently iSCSI uses TCP/IP, which encapsulates SCSI commands within TCP packets. This creates an overhead but does allow the protocol to be routed over any distance. AoE doesn't use TCP, it uses its own protocol so doesn't suffer the TCP overhead, but can't be routed. This isn't that much of an issue as there are plenty of storage networks which are locally deployed.

Ethernet hardware is cheap. I found a 24 port GigE switch for less than £1000 (£40 a port). NICs can be had for less than £15. Ethernet switches can be stacked providing plenty of redundancy options. This kills fibre channel on cost. iSCSI can use the same hardware; AoE is more efficient.

AoE is already being bundled with Linux, drivers are available for other platforms. Does this mean the end of iSCSI? I don't think so; mainly because AoE is so different and also more importantly it isn't routable. However what AoE does offer is another alternative which can use standard cheap, readily available products. From what I've read, AoE is simple to configure too; certainly with less effort than iSCSI. I hope it has a chance.

Brocade on the up

Brocade shares were up 10.79% today. I know they posted good results but this is a big leap for one day. I wish I hadn't sold my shares now! To be fair, I bought at $4 and sold at $8 so I did OK - and it was some time ago.

So does this bode well for the McDATA merge? I hope so. I've been working on Cisco and the use of VSANs and I'm struggling to see what real benefit I can get out of them. Example: I could use VSANs to segregate by: Line of Business; Storage Tier; Host Type (Prod/UAT/DEV). Doing this immediately gives me 10's of combinations. Now the issue is I can only assign a single storage port to one VSAN - so I have to decide; do I want to segment my resources to the extent I can't use an almost unallocated UAT storage port when I'm desperate for connectivity for production? At the moment I see VSANs as likely to create more fragmentation than anything else. There's still more thinking to do.

I'd like to hear from anyone who has practical standards for VSANs. It would be good to see what best practice is out there.

Backup Trawling

I had a thought. As we back up more and more data (which we must be, as the amount of storage being deployed increases at 50-100% per year, depending on who you are) then, there must be more of an issue finding the data which needs to be restored. Are we going to need better tools to trawl the backup index to find what we want?

Virtually There

VMware looks like it is going to be a challenge; I'm starting to migrate standard storage tools into a VMware infrastructure. First of all, there's a standard VMware build for Windows (2003). Where should the swap file go? How should we configure the VMFS that it sits on? What about the performance issues in aligning the Windows view of the (EMC) storage with the physical device so we get best performance? What about Gatekeeper support? and so on.

It certainly will be a challenge. First thing that I need to solve, is if I have a LUN presented as a raw device to my VM guest and that LUN ID is over 128, although the ESX server can see it, when ESX exports it directly to the Windows guest, it can't be seen. I've a theory that it could be the generic device driver on Windows 2003 that VMware uses. I can't prove it (yet) and as yet no-one on the VMware forum has answered the question. Either they don't like me (lots of other questions posted after mine have been answered) or people don't know....

Continuous Protection

I've been looking at Continuous Data Protection products today, specifically those which don't need the deployment of an agent and can use Cisco's SANTap technology. EMC have released RecoverPoint (a rebadged product from Kashya) and Unisys have SafeGuard.

SANTap works by creating a virtual initiator, duplicating all of the writes to a standard LUN (target) within a Cisco fabric. This duplicate data stream is directed at the CDP appliance which stores and forwards it to another appliance located at a remote site where it is applied to a copy of the original data.

As the appliances track changed blocks and apply them in order, they allow recovery to any point in time. This potentially is a great feature; imagine being able to back out a single I/O operation or to replay I/O operations onto a vanilla piece of data.

Whilst this CDP technology is good, it introduces a number of obvious questions on performance, availability etc, but for me the question is more about where this technology is being pitched. EMC already has replication in the array in the form of SRDF which comes in many flavours and forms. Will RecoverPoint complement these or will, in time, RecoverPoint be integrated into SRDF as another feature?

Who can say, but at this stage I see another layer of complication and decision on where to place recovery features. Perhaps CDP will simply offer another tool in the amoury of the Storage Manager.

Cisco, Microwaves and Virtualisation

So I've not posted in October so far and the month is half over. To my defence I spent a week in South Africa doing an equipment (Cisco) installation. No it wasn't a holiday but I did see the fantastic table mountain, which is spectacular and well worth a visit.

Part of the installation involved deployment of SRDF between two symmetrix arrays using Cisco 9216i switches. These have two IP ports and can be used for iSCSI or in this case FCIP as we had to provide the SRDF links across IP. Whilst this all sounds fine, the IP link was in fact over a microwave connection rather than a fixed line installation. Telecoms are prohibitively expensive in SA and sometimes microwave is the only option due to the high cost of fixed line installations.

Installation and configuration of the links was simple, including enabling SRDF. However my big concern is performance (I should note that this is no way a synchronous implementation, but an async one). The IP link is not dedicated to storage and being used for other purposes so fcping responses from the Cisco switches were very variable. At this point we haven't fully enabled SRDF but the next stage is to test performance of the link. As I see it, we need to monitor SRDF stats with ECC Performance Monitor, SRDF/A response times and the lag time of unwritten I/Os not committed to the remote site. The solution needs significant monitoring to ensure all links are active; with SRDF it is possible to monitor the status of a remote SRDF link using the "symrdf ping" command; this needs to be being issued reguarly if not every 5 minutes or less. More updates as I have them.

I spoke to an analyst today (it's Storage Expo in the UK) on the subject of virtualisation and in particular HDS' Universal Volume Manager. He was asking my view on where virtualisation is headed. I still think the switch is the right place, long term, for virtualisating the storage infrastructure. In the short term though, discrete hardware array virtualisation is a good thing. UVM can provide cost savings (on significant virutalised volumes of data) and additional functionality, however HDS will have to up their game to retain the virtualisation crown as time progresses. Specifically they need to address the issue of a failure in the USP when so much storage could be dependent on one subsystem. A clustered solution could be the answer here. Time will tell.

To Copy or not to Copy?

Sony have just announced the availability of their next generation of AIT; version 5. More on AIT here http://www.storagewiki.com/ow.asp?Advanced%5FIntelligent%5FTape. Speeds and feeds; 400GB native capacity, 1TB compressed and 24MB/s write speed. The write speed seems a little slow for me but the thing that scares me more are the capacity figures. 1TB - think about it 1TB! That's a shedload of data. Whilst that's great for density in the datacentre, it isn't good if you have a tape error. Imagine a backup failing after writing 95% of the data of a 700GB backup - or more of an issue, finding multiple read errors on a TB of data on a single cartridge.

No-one in their right mind would put 1TB of data onto a disk and hope the disk would never fail. So why do we do it with tape? Well probably because tape was traditionally used as a method of simply recovering data to a point in time. If one backup wasn't usable, you went back to the previous one. However, the world is a different place today. Increased regulation means backups are being used to provide data archiving facilities in the absence of proper application based archival. This means that every backup is essential as it indicates the state of data at a point in time. Data on tape is therefore so much more valuable than it used to be.

So, I would always create duplicate backups of those (probably production) applications which are most valuable and can justify the additional expense. That means talking to your customers and establishing the value of backup data.

Incidentally, you should be looking at your backup software. It should allow restarting backups after hardware failure. It should also allow you to easily recover the data in a backup from a partially readable tape. I mean *easily*, not oh, it can be done, but its hassle and you have to do a lot of work. Alternatively, look at D2D2T (http://www.storagewiki.com/ow.asp?Disk%5FTo%5FDisk%5FTo%5FTape).....

It's not easy being green

OK, not a reference to a song by Kermit the Frog, but a comment relating to an article I read on The Register recently (http://www.theregister.co.uk/2006/09/22/cisco_goes_green/). Cisco are attempting to cut carbon emissions by cutting back on travel, etc. Whilst this is laudible, Cisco would get more green kudos if they simply made their equipment more efficient. A 10% saving in power/cooling for all the Cisco switches in the world would make the reduction on corporate travel look like a drop in the ocean.

Standards for Shelving

Just found this the other day: http://www.sbbwg.org/home/ - a group of vendors working to get a common standard for disk shelves. Will we see a Clariion shelf attached to a Netapp filer head?

Common Agent Standards

The deployment of multiple tools into a large storage environment does present problems. For example, EMCs ECC product claims to support HDS hardware and it does. However it didn't support the NSC product correctly until version 5.2 SP4. Keeping the agents up to date for each management product to get it to support all hardware is a nightmare. I haven't even discussed host issues. Simply having to deploy multiple agents to lots of hosts presents a series of problems; will they be compatible, how much resource will they all demand from the server, how often will they need upgrading, what level of access will be required?

Now the answer would be to have a common set of agents which all products could use. I thought that's what CIM/SMI was supposed to provide us, but at least 4 years after I read articles from the industry saying the next version of their products would be CIM compatible I still don't see it. For instance, looking at the ECC example I mentioned above, ECC has Symm, SDM, HDS and NAS agents to manage each of the different components. Why can't a single agent collect for each and any subsystem?

Hopefully, someone will correct me and point out how wrong I am, however in the meantime, I'd like to say what I want:

1. A single set of agents for every product. This would also be a single set of hosts agents. None of this proxy agent nonsense where another agent has to sit in the way and manage systems on behalf of the system itself.
2. A consistent upgrade and support model. All agents should work with all software, however if the wrong version of an agent is installed, then it simply reports back on the data available.
3. The ability to upgrade any agent to introduce new features without direct dependence on software upgrades.

Pay Attention 007...

Sometimes things you should spot just pass you by when you're not paying attention. So it is for me with N-Port ID Virtualisation. Taking a step back; mainframes had virtualisation in the early 90s. EMIF (ESCON Multi-Image Facility) allowed a single physical connection to be virtualised and shared across multiple LPARs (domains). When I was working on Sun multi-domain machines a few years ago, I was disappointed to see I/O boards couldn't share their devices between domains, so each domain needed dedicated physical HBAs. More recently I've been looking at having large servers with lots of storage using a data and tape connection - hopefully through the same physical connection, but other than using dual port HBAs, it wasn't easily possible without compromising quality of service. Dual port HBAs don't really solve the problems because I still have to pay for extra ports on the SAN.

Now Emulex have announced their support of N-Port ID Virtualisation (NPIV). See the detail here http://www.emulex.com/press/2006/0918-01.html. So what does it mean? For the uninitiated, when a fibre channel device logs into a SAN, it registers its physical address (WWN, World Wide Name) and requests a node ID. This ID is used to zone HBAs to target storage devices. NPIV allows a single HBA to request more than one node ID. This means if the server supports virtual domains (like VMware, XEN, or MS Virtual Server) then each domain can have a unique WWN and be zoned (protected separately). Also this potentially solves my disk/tape issue allowing me to have multiple data types through the same physical interface. Tie this with virtual SANs (like Cisco VSANs) and I can put quality of service onto each traffic type at the VSAN level. Voila!

I can't wait to see the first implementation; I really hope it does what it says on the tin.

RSS Update

I've always gone on and on about RSS and XML and how good technologies they are; XML as a data exchange technology and RSS to provide information feeds in a consistent format. My ideal world is to have all vendor information published via RSS. By that I mean not just the nice press releases and how they've sold their 50 millionth hard drive this week to help orphanages, but useful stuff like product news, security advisories and patch information.

Finally vendors are starting to realise this is useful. Cisco so far seems the best although IBM look good as do HP. McDATA and Brocade are nowhere, providing their information in POHF (Plain Old HTML Format). Hopefully all vendors of note will catch up, meanwhile I've started a list on my Wiki (http://www.storagewiki.com/ow.asp?Vendor%5FNews%5FFeeds), feel free to let me know if I've missed anyone.

A Mini/McDATA Adventure?

Apparently one in 6 cars sold by BMW is a mini. It is amazing to see how they have taken a classic but fading brand and completely re-invented it into a cool and desirable product. McDATA have just released an upgraded version of their i10K product, branded the i10K Xtreme. http://www.mcdata.com/about/news/releases/2006/0913.html This finally brings 4Gb/s speed and VSAN/LPAR technology allowing resources in a single chassis to be segmented for improved managability and security. I understand that the Brocade acquisition of McDATA is proceeding at a pace. It will be interesting to see how McDATAs new owners will treat their own McDATA "mini" going forward.