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2Mar/11Off

Compellent gets Hyper efficient storage tiering

TechOps Guy: Nate

So according to this article from our friends at The Register, Compellent is considering going to absurdly efficient storage tiering taking the size of data being migrated to 32kB from their currently insanely efficient 512kB.

That's just insane!

For reference, as far as I know:

  • 3PAR moves data around in 128MB chunks
  • IBM moves data around in 1GB chunks (someone mentioned that XIV uses 1MB)
  • EMC moves data around in 1GB chunks
  • Hitachi moves data around in 42MB chunks (I believe this is the same data size they use for allocating storage to thin provisioned volumes)
  • NetApp has no automagic storage tiering functionality though they do have PAM cards which they claim is better.

I have to admit I do like Compellent's approach the best here, hopefully 3PAR can follow. I know 3PAR allocates data to think provisioned volumes in 16kB chunks, what I don't know is whether or not their system is adjustable to get down to a more granular level of storage tiering.

There's just no excuse for the inefficient IBM and EMC systems though, really, none.

Time will tell if Compellent actually follows through with going as granular as 32kB, I can't help but suspect the CPU overhead of monitoring so many things will be too much for the system to bear.

Maybe if they had purpose built ASIC...

 

24Aug/10Off

EMC and IBM’s Thick chunks for automagic storage tiering

TechOps Guy: Nate

If you recall not long ago IBM released some SPC-1 numbers with their automagic storage tiering technology Easy Tier. It was noted that they are using 1GB blocks of data to move between the tiers. To me that seemed like a lot.

Well EMC announced the availability of FAST v2 (aka sub volume automagic storage tiering) and they too are using 1GB blocks of data to move between tiers according to our friends at The Register.

Still seems like a lot. I was pretty happy when 3PAR said they use 128MB blocks, which is half the size of their chunklets. I thought to myself when I first heard of this sub LUN tiering that you may want a block size as small as, I don't know 8-16MB. At the time 128MB still seemed kind of big(before I had learned of IBM's 1GB size).

Just think of how much time it takes to read 1GB of data off a SATA disk (since the big target for automagic storage tiering seems to be SATA + SSD).

Anyone know what size Compellent uses for automagic storage tiering?

14Apr/10Off

First SPC-1 Numbers with automagic storage tiering

TechOps Guy: Nate

IBM recently announced that they are adding an "easy tier" of storage to some of their storage systems. This seems to be their form of what I have been calling automagic storage tiering. They are doing it at the sub LUN level in 1GB increments. And they recently posted SPC-1 numbers for this new system, finally someone posted numbers.

Configuration of the system included:

  • 1 IBM DS8700
  • 96 1TB SATA drives
  • 16 146GB SSDs
  • Total ~100TB raw space
  • 256GB Cache

Performance of the system:

  • 32,998 IOPS
  • 34.1 TB Usable space

Cost of the system:

  • $1.58 Million for the system
  • $47.92 per SPC-1 IOP
  • $46,545 per usable TB

Now I'm sure the system is fairly power efficient given that it only has 96 spindles on it, but I don't think that justifies the price tag. Just take a look at this 3PAR F400 which posted results almost a year ago:

  • 384 disks, 4 controllers, 24GB data cache
  • 93,050 SPC-1 IOPS
  • 26.4 TB Usable space (~56TB raw)
  • $548k for the system (I'm sure prices have come down since)
  • $5.89 per SPC-1 IOP
  • $20,757 per usable TB

The system used 146GB disks, today the 450GB disks seem priced very reasonably, I would opt for those instead and get the extra space for not much of a premium.

Take a 3PAR F400 with 130 450GB 15k RPM disks, that would be about 26TB of usable space with RAID 1+0 (the tested configuration above is 1+0). That would give about 33.8% of the performance of the above 384-disk system, so say 31,487 SPC-1 IOPS, very close to the IBM system and I bet the price of the 3PAR would be close to half of the $548k above (taking into account the controllers in any system are a good chunk of the cost). 3PAR has near linear scalability making extrapolations like this possible and accurate. And you can sleep well at night knowing you can triple your space/performance online without service disruption.

Note of course you can equip a 3PAR system with SSD and use automagic storage tiering as well, they call it Adaptive Optimization, if you really wanted to. The 3PAR system moves data around in 128MB increments by contrast.

It seems the cost of the SSDs and the massive amount of cache IBM dedicated to the system more than offset the benefits of using lower cost nearline SATA disks in the system. If you do that, what's the point of it then?

So consider me not impressed with the first results of automagic storage tiering. I expected significantly more out of it. Maybe it's IBM specific, maybe not, time will tell.