The Impact of Disruptive Technologies on the Professional Storage Market
by Johan De Gelas on August 5, 2013 9:00 AM EST- Posted in
- IT Computing
- SSDs
- Enterprise
- Enterprise SSDs
NetApp: Flash Anywhere
Nutanix, CloudFounders/Amplidata, and Fusion-IO (covered on page eight) are clearly challenging the current market leaders NetApp and EMC. We decided to take a closer look at how the giants respond by looking at the latest products of NetApp. NetApp's first step with using flash memory was called “flash cache”. NetApp simply added a PCIe flash card and inserted it into its FAS V6200 storage arrays.
It was a quick way of adding some performance, but it was far from exploiting the true potential of NAND memory. First of all, the flash cache was only used for reads and secondly the cache used a very simple but hardly efficient FIFO eviction algorithm. Case studies (done by NetApp Customers) with applications with a typical read/write mix reported about 30% more IOPs and on average 20% lower response times when arrays with 10K RPM SAS disks where replaced by an array with a massive flash cache and slightly slower 7200 RPM disks.
Considering how large the gap is between flash memory and magnetic disks, and the small gap between 10K and 7.2K RPM disks, that is rather underwhelming. Part of the reason is of course that these arrays already have a healthy amount (4-8GB) of NVRAM (Non Volatile RAM) that caches the hottest data and makes writes more sequential. However, the list price of a flash cache module is anywhere between $16000 (256GB) and $50000 (1TB).
In a published benchmark, six FAS6240 with 192 15K RPM disks (costing $1.5 million in total!) achieved about 250k IOPs, or about 40K IOPs per array. To sum it up: it's a very high premium for an underwhelming but very welcome performance boost. Only customers who use read dominated applications (like warehouse / OLAP app) can really expect excellent performance.
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WeaselITB - Tuesday, August 6, 2013 - link
Fascinating perspective piece. I look forward to the CouldFounders review -- that stuff seems pretty interesting.Thanks,
-Weasel
shodanshok - Tuesday, August 6, 2013 - link
Very interesting article. It basically match my personal option on SAN market: it is an overprice one, with much less performance per $$$ then DAS.Anyway, with the advent of thin pools / thin volumes in RHEL 6.4 and dmcache in RHEL 7.0, commodity, cheap Linux distribution (CentOS costs 0, by the way) basically matche the feature-set exposed by most low/mid end SAN. This means that a cheap server with 12-24 2.5'' bays can be converted to SAN-like works, with very good results also.
In this point of view, the recent S3500 / Crucial M500 disks are very interesting: the first provide enterprise-certified, high performance, yet (relatively) low cost storage, and the second, while not explicitly targeted at the enterprise market, is available at outstanding capacity/cost ratio (the 1TB version is about 650 euros). Moreover it also has a capacitor array to prevent data loss in the case of power failure.
Bottom line: for high performance, low cost storage, use a Linux server with loads of SATA SSDs. The only drawback is that you _had_ to know the VGS/LVS cli interface, because good GUIs tend to be commercial products and, anyway, for data recovery the cli remains your best friend.
A note on the RAID level: while most sysadmins continue to use RAID5/6, I think it is really wrong in most cases. The R/M/W penalty is simply too much on mechanincal disks. I've done some tests here: http://www.ilsistemista.net/index.php/linux-a-unix...
Maybe on SSDs the results are better for RAID5, but the low-performance degraded state (and very slow/dangerous reconstruction process) ramain.
Kyrra1234 - Wednesday, August 7, 2013 - link
The enterprise storage market is about the value-add you get from buying from the big name companies (EMC, Netapp, HP, etc...). All of those will come with support contracts for replacement gear and to help you fix any problems you may run into with the storage system. I'd say the key reasons to buy from some of these big players:* Let someone else worry about maintaining the systems (this is helpful for large datacenter operations where the customer has petabytes of data).
* The data reporting tools you get from these companies will out-shine any home grown solution.
* When something goes wrong, these systems will have extensive logs about what happened, and those companies will fly out engineers to rescue your data.
* Hardware/Firmware testing and verification. The testing that is behind these solutions is pretty staggering.
For smaller operations, rolling out an enterprise SAN is probably overkill. But if your data and uptime is important to you, enterprise storage will be less of a headache when compared to JBOD setups.
Adul - Wednesday, August 7, 2013 - link
We looked at Fusion-IO ioDrive and decided not to go that route as the work loads presented by virtualize desktops we offer would have killed those units in a heartbeat. We opted instead for a product by greenbytes for our VDI offering.Adul - Wednesday, August 7, 2013 - link
See if you can get one of these devices for review :)http://getgreenbytes.com/solutions/vio/
we have hundreds of VDI instances running on this.
Brutalizer - Sunday, August 11, 2013 - link
These Greenbyte servers are running ZFS and Solaris (illumos)http://www.virtualizationpractice.com/greenbytes-a...
Brutalizer - Sunday, August 11, 2013 - link
GreenByte:http://www.theregister.co.uk/2012/10/12/greenbytes...
Also, Tegile is using ZFS and Solaris:
http://www.theregister.co.uk/2012/06/01/tegile_zeb...
Who said ZFS is not the future?
woogitboogity - Sunday, August 11, 2013 - link
If there is one thing I absolutely adore about real capitalism it is these moments where the establishment goes down in flames. Just the thought of their jaws dropping and stammering "but that's not fair!" when they themselves were making mockery of fair prices with absurd profit margins... priceless. Working with computers gives you so very many of these wonderful moments of truth...On the software end it is almost as much fun as watching plutocrats and dictators alike try to "contain" or "limit" TCP/IP's ability to spread information.
wumpus - Wednesday, August 14, 2013 - link
There also seems to be a disconnect in what Reed-Solomon can do and what they are concerned about (while RAID 6 uses Reed Solomon, it is a specific application and not a general limitation).It is almost impossible to scale rotating discs (presumably magnetic, but don't ignore optical forever) to the point where Reed-Solomon becomes an issue. The basic algorithm scales (easily) to 256 disks (or whatever you are striping across) of which typically you want about 16 (or less) parity disks. Any panic over "some byte of data was mangled while a drive died" just means you need to use more parity disks. Somehow using up all 256 is silly (for rotating media) as few applications access data in groups of 256 sectors a time (current 1MB, possibly more by the time somebody might consider it).
All this goes out the window if you are using flash (and can otherwise deal with the large page clear requirement issue), but I doubt that many are up to such large sizes yet. If extreme multilevel optical disks ever take over, things might get more interesting on this front (I will still expect Reed Solomon to do well, but eventually things might reach the tipping point).
equals42 - Saturday, August 17, 2013 - link
The author misunderstands how NetApp uses NVRAM. NVRAM is not a cache for the hottest data. Writes are always to DRAM memory. The writes are committed to NVRAM (which is mirrored to another controller) before being acknowledged to the host but the write IO and its commitment to disk or SSD via WAFL sequential CP writes is all from DRAM. While any data remains in DRAM, it can be considered cached but the contents of NVRAM do not constitute nor is it used for caching for host reads.NVRAM is only to make sure that no writes are ever lost due to a controller loss. This is important to recognize since most mid-range systems (and all the low-end ones I've investigated) do NOT protect from write losses in event of failure. Data loss like this can lead to corruption in block-based scenarios and database corruption in nearly any scenario.