SAN Solution

[CHiLL]

I'm pretty new to all this, so I'd like some advice on SANs. We are debating whether to implement a SAN into our network. W have several file servers across the site, which are nearly full of data. We'd like a central storage solution, so we can use our servers just for applications, rather than that and file shares.

All of our network equipment is HP, provided by Zentek, and HP do SAN solutions, so they're the ones that are drawing our eyes at the moment. However, I don't know of any decent other solutions from other companies.

Ideally, we'd like the chassis and a customisable amount of hard drives. I've noticed HP's solutions are including the drives as well as the chassis. Such as 7TB over 42 drives. What if we don't want to use all the 42 drives? We don't want to pay for them all. Having less, a more tailored solution, would allow for scalability in the future.

I don't know much about SAN connectivity, from the little I've researched, a full Fibre connection would be best for us I think.

How equipment would we need to purchase as well as the actual SAN to get it up and running? Or is it simply a case of buying a SAN, buying and fitting a fibre connection to the nominated server and that's it for the hardware?

I've probably forgot some other questions I had, so I may come back with random questions. I have read some of the other relevant threads made about SANs in the past year, but with my lack of knowledge on the subject, I'm not really understanding it.

Any help would be greatly appreciated.

[Jay]

I have spent some time looking into SANs and I have found that Dells EQ are very good. If I was you (depending on the size of the implimentation) I would get either Dell or HP to come out, sit down with you and talk you through the options, they are pretty good.

[burble]

What sort of data is going to be on the SAN? Fibre channel is an option but iSCSI is not to be ignored especially with 10GbE ports. If you do go iSCSI then keep your iSCSI traffic on separate fabric than your LAN. It'll add to the initial costs but it's definitely worth it.

Getting a SAN to work is usually a doddle but getting it setup in the optimal way is less so.

What SAN you should buy is dependent on may things - is it transactional data? Do you need replication? Do you need SATA or SAS discs? Maybe SSD's? Maybe different discs for different tiers of data? The list goes on.

The number of discs is important, not just from a capacity perspective but generally speaking the more spindles you have the better the performance.

The Dell EqualLogic boxes are pretty good, I've got a few PS6000's and 6010's knocking about and until Sunday night they'd never missed a beat. On Sunday night though the primary controller in a PS6000 in Brussels failed and for some reason the failover to the standby didn't work so the array went down which of course caused problems for all the virtual machines that live on it.

Luckily I had serial port access so able to get it up and running again and have since (yesterday infact) replaced the controller.

Dell are very keen with their pricing especially when it gets to end of quarter so there will be room for movement on their quote.

[Moby-Dick]

can open , worms everywhere

its quite a big challenge to put a SAN in , and a large number of ways of achieving it.


Have you got some serious budget available ? storage networking isn't cheap

If you want to go with fibre, you'll need a fibre ( fabric) switch as well as fibrechallen HBA's

assuming you go with somethign like 4GB fibre you will want a pair of switches & a dual channel ( or pair of single channel ) HBA's in each server you want to fibre attach. This is not cheap

A wlel setup ethernet based implementation can be just as versatile - I know of companies with 3,000 staff who have never used anythign more than 1GB iSCSI and they are pretty happy with it.

Unless you have an SSD caching/tiering layer , the performnce of a SAN comes from the number of Spindles running on it - you may find you need to run more drives than you need capacity for in order to get the performance out of it.

for Low cost kit , the Equalogic Stuff is good , as is the Lefthand kit from HP ( I particularly like their network RAID ) - EMC and Netapp also have some handy entry level solutions ( the EMC VNXe - being the latest and greatest )

[CHiLL]

I'll provide a little information. This is a little project from my boss as an avenue to explore. He gets the new budget in April, and we don't know how much money we will have. We're just opening doors really.

We are a secondary school, which has a 20Gb Fiber backbone between the core switches, 10Gb fiber from the core switches to the client switches, and 1Gb connections from those to the workstations.

Our file servers currently have SCSI discs at 15,000RPM with RAID. We'd like to consolidate this into one SAN box, controlled by one server. We have a VMWare ESX Server, which I've read can manage a SAN devices.

My boss has said that Fibre is the preferred connection from the SAN box to the rest of the network. For this, we'd need a fibre switch between the SAN and the server.

Howcome people chose SAN over NAS, or the other way round?
Does the SAN have to connect to a server, can it not plug directly into the network (I know they use different protocols than network traffic, but I'm not sure on anything else) and the SAN can be managed by another server on the network?

[Moby-Dick]

depends on the size of the device. most Storage Networking devices woudl have a management server ,which would need to be connected to the storage fabric in the same way that your network management software would.

Schools are an interesting one as I know you can have a dirty big workload and a teeny weeny budget to run it with

ESX wasn't designed in SAN management devices in mind. I'm not sure what you read or where you read it , but I think you might have the wrong end of the stick ( certain vendors may well have plugins to be able to do some SAN stuff from virtual center , but that is quite often just pointing to the web managment point - with a few exceptions )

File Level or Block level is a big question - what you want is device that does both

[Jay]

you are aware of the cost of a half decent (still low end) iSCSI SAN? 2TB RAID 10 (SAS) is about £20,000

[oolon]

I have an entry level hp san (MSA 1500) which is probably you the entry level you were looking at (but a newer model), its little better than a DAS (Direct attached storage) encloser however it is alot more expensive, and its not very good. The software on my SAN is really naff, you have to use storage controller software on a HP computer that talks down the fiber channel to the san to configure it. Hence anyone with admin access to any server could reconfigure it, I am sure its better now, however having also used mid and high range IBM and Hitachi kit, they are all a bit "naff", software wise, and do alot less than I expected. With shared storage you also need to consider what effect multiple servers using the same array might have on the systems. Ie if you have one server working one disk group very hard all the others will be impacted.

HBAs (Host bus adapters) are really expensive san switches are sold like razorblades where you have by more licences to up the port count, if its fibre they don't even come with the SFPs which cost 100 quid + a pop.

Then you start thinking about the bandwidth, Great 4Gbit fiber well SATA 3 is 6 per disk! and all your disk is comming down that port, or a pair if you load balance it. If you have a switch that is also then shared with other computers.

There are a number of things a SAN can do and you have to ask yourself if you really need it.
1) I have lots of servers and I want to make sure I have all the storage where my customer data is, is locked away.
2) I want shared storage, the same bit of disk is seen a block device on more than one machine. Great for clustering however don't forget your need redundant controllers on the san, multiple switches etc otherwise you still have a single point of failure.

If your not looking at a dual fibre channel network then frankly look at iSCSI or even better a SAS DAS enclose, many of those can even present to multiple servers and dual path.

There are a number of "generic" sans like promise or NexStor you could consider these have the advantage you don't have to buy very expensive branded drives and SAS based (rather than fibre channel) drive based systems and even use SATA drives if you want to put alot of storage in it.

You may think you prefer a big name brand, well LSI make IBMs midrange kit. Hitachi makes Suns high range etc. Most kit is rebadged stuff.

Most san stuff comes with a service contract this means second hand stuff is worthless and you have to pay for it year on year.

As to buying the bits most sans come without the drives, you can add more later, on the fly. Most systems have Head units that may or may not support drives in there own right, then have save sheives or cabinents, allowing more drives to be installed. As you want a whole heap of storage for virtual machines rather than the disk going to multiple machine a DAS system (Dyslexic San!) is probably a better solution, you will still have configurable arrays. If you thinking of presenting storage on the fly, that can take a lot of work to get things right. of course you can't do online migration of vms to another server without a san/network based block device, and that can be rather fun!

[Moby-Dick]

There are more user friendly entry level SANs in existance ( HP SAN's are not the most straightforward in the world - well untill you hit the ex 3PAR kit - the EVA's are easyier but nowhere as easy to use as the New EMC kit or IBM XIV )

but thats a really good primer from Oolon as to why fibre channel prpobably isn't for you

a good iscsi setup should be more than adequate.

[oolon]

but thats a really good primer from Oolon as to why fibre channel prpobably isn't for you

It kind of sucks really talking it down, because I think SANs are great particularly fibre channel which is very cool, fortunately I managed to get some that was being disposed of, shame the electric bill is to high to run it all the time. My dream of a HTPC with just a dual fibre HBA never happened, and of course SSDs now allow for a no moving part computer which is much cheaper. The thought often with SANS is I can buy now and I can decide later exactly where I wish to put the storage later. The problem is the price of the equipment you could have probably put the "all" the storage on a couple of servers, using a cheaper solution.

Another "good" reason I forgot for fibre channel or using optical Ethernet, is it does allow you to electrically bits of equipment, this is particularly useful if the equipment is in different buildings.

[Jay]

just to revive an oldish thread.

I got my hands on this monster today.


just over 1TB in RAID 10

[madman045]

New toy at home Jay?

[Jay]

god no, £30,000 is a bit much for a home toy!

Its a loan unit from Dell.

[burble]

If it's running firmware v5.0.2 then try to upgrade it ASAP to v5.0.4. The older version had a really nasty bug where under certain circumstances if a controller failed it wouldn't fail over to the spare controller meaning that all the data on the array is unavailable.

One of our 6010XV's suffered from that problem a couple of months ago and the fix is it pull the power cables on the box and let it boot onto the other controller then to replace the faulty controller. Not fun when it's 10pm on a Sunday and the SAN is in a DC in Brussels with no remote hands available.

[1stRaven]

Just looking into these through work not. Scary money in a way. Dell just provided a £79,000 quote for a SAN unit with a fail-over reduced IO unit in a 2nd site. Granted, this is for a 5tb San in Raid 10 on SAS 15k drives (fail-over is Sata drives) .

Looking at 3 providers - Dell (Preferred as we are a Dell house), HP or NetApp.

[Moby-Dick]

Enterprise Storage is an expensive hobby