Sometimes I think storage vendors use a special type of man-ruler when measuring the size of their bits and bytes; especially when it comes down to working out how much storage their array can support. Please note, this is not about utilisation; this is about the maximum number of disks that a array can support and actually use.
Every time a vendor announces a new array; there is inevitably an increase in the maximum spindle count and almost invariably as spindles get bigger, there is a commensurate increase in capacity. More spindles, more spindles and even more spindles are the order of the day. These beasts get bigger and bigger according to their spec sheets but then you have conversations with your account manager.
'Okay, so how much disk can I put in your array?'
'Well, that depends; what are you going to use it for?'
'Oh you know, stuff!'
'Let us do a detailed study and we'll get back to you…'
'But you say you support 1000 spindles?'
'Ahhh, we do but only when the wind blows from NNE and the Sun is waxing in Aries and the moon is mooning Virgo! Then we support 1000 spindles but at all other times, we support rather less than we say! I can't tell you how much less…but we do support less or more, it depends!'
At times, the whole business is more opaque than a black-out blind! And when software is priced on a per frame/head/array basis; sometimes based on the maximum capacity that an array could support on that special day when it can support its maximum amount of disk, it's quite frankly mildly irritating!
Lets have sensible incremental software pricing, lets have proper disclosure as to what is meant when talking about maximum capacity and lets get some transparency into this business.
Great point made Martin.
I don’t want to pick on EMC, but the last I checked, DMX4 supports 2400 drives, but if you need more than 1920, you need to talk to the account manager..
Good points all around.
For BlueArc, we support a specific amount of storage in a namespace, depending on the product purchased. (i.e. 1 PB for the 2100, 2 PB for the 3100 and 4 PB for the 3200)
That’s useable capacity, not raw capacity, and it is not bound on the # of spindles, so you can get 4 PB whether you are using 450 GB drives or 1 TB drives.
Further, our software pricing is per node in practically all cases, meaning that as we have one of the highest capacity per node ratios out there, the software costs are comparatively low.
So to answer your question – “How much disk can I put in your array?” 4 petabytes useable, period, any type you like, and yes, we can address all of it.
Fair enough question, Martin.
But before I answer – how big is “big enough” these days? If an array could offer (say) 4TB usable with 4000 1TB SATA drives, or 10,000 400GB FC drives, would that be:
a) Great!
b) Too much to manage as a single entity
c) Too many eggs in one basket
d) Still not enough
e) All of the above B^)
And for extra credit, what’s the expected average LUN size – how many LUNs (or CKD volumes) would you expect to need in order to fully utilize (for example) 4TB of usable capacity?
Louis, is there a limit to the number of files that you support in the namespace? BlueArc is a NAS and it’s rather different to block.
Barry, I think what I am looking for is some honesty. The number of conversations I have with array manufacturers along the lines of ‘Yes, we support x numbers of disks but really we’d advise you to only use x/2!’ There are always edge-cases where x might be the answer or x/4 might be the answer.
Martin, we do not have a limit to the number of files in a namespace. We do have a limit of 16 million files per directory. The default limit is 4 million per directory, but it can be changed with the administrative Command Line Interface (CLI).