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: Automatic Tiering and More Flash Goodness
Most vendors did not do much better than NetApp as they used an advocated automatic tiering, meaning that hot data was moved from the slow magnetic disks to the flash disk. Although it sounds nice, the reality was that it did not solve some performance bottlenecks. As the process was not real-time, you could be hitting the disks a lot for a piece of data before the data was finally moved towards the flash tier. Also migrating data around is not very energy friendly as it wastes a lot of processing and storage bandwidth.
To sum it up: NetApp's Flash Cache did better than the "automatic flash tier" of other vendors, but the flash cache performance/dollar ratio was not exactly something to write home about.
Last year, NetApp went a step further. The storage arrays could be expanded with a “flash pool”, a storage pool consisting of a RAID group of SSDs (100, 200, or 800GB) that caches the random reads and writes of the volumes inside a magnetic hard disk pool. All writes are first written to the NVRAM and then flushed to the disks. However, an overwrite of random write is written to the flash pool. This greatly improves performance when you update the same data over and over again in a small time period because the update is only propagated to the disks when the data is not changed for some time. Sequential writes and reads are still sent to the disks, which is an intelligent way to make the most of your SSDs. Also, the flash pool is an LRU (Least Recently Used) cache.
It is ironic to notice that NetApp quotes customers who reported 100s of ms for critical requests in case studies. While the case studies did make the flash based SAN shine, they also show how a few years ago, SAN arrays were expensive and not delivering. Luckily, those customers now report that flash pools reduced the response time to 5 ms. It is good that the newest NetApp technology has accelerated this, but it is also a clear example that even high-end SANs failed to deliver good performance to customers just a year ago.
But flash pool and flash cache do not give the performance benefits that server side flash cache delivered with Fusion-IO. So something really interesting happened: NetApp announced Flash Accel, making sure its SANs could work together with server side flash caches. Even more interesting is that NetApp is not charging anything for this software, probably to make sure that the current NetApp customers do not get lured away by other server side storage solutions.
Existing customers can simply download the ESXi 5.0/Windows 2008 agent. Each VM needs to get an agent and an ESXi host, so Flash Accel works at the moment with only a limited number of configurations. However, it's quite disruptive to witness a typical SAN vendor promoting server side caching. Just a year ago, most SAN vendors were downplaying this trend.
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Jammrock - Monday, August 5, 2013 - link
Great write up, Johan.The Fusion-IO ioDrive Octal was designed for the NSA. These babies are probably why they could spy on the entire Internet without ever running low on storage IO. Unsurprisingly that bit about the Octal being designed for the US government is no longer on their site :)
Seemone - Monday, August 5, 2013 - link
I find the lack of ZFS disturbing.Guspaz - Monday, August 5, 2013 - link
Yeah, you could probably get pretty far throwing a bunch of drives into a well configured ZFS box (striped raidz2/3? Mirrored stripes? Balance performance versus redundancy and take your pick) and throwing some enterprise SSDs in front of the array as SLOG and/or L2ARC drives.In fact, if you don't want to completely DIY, as many enterprises don't, there are companies selling enterprise solutions doing exactly this. Nexenta, for example (who also happen to be one of the lead developers behind modern opensource ZFS), sell enterprise software solutions for this. There are other companies that sell hardware solutions based on this and other software.
blak0137 - Monday, August 5, 2013 - link
Another option for this would be to go directly to Oracle with their ZFS Storage Appliances. This gives companies the very valuable benefit of having hardware and software support from the same entity. They also tend to undercut the entrenched storage vendors on price as well.davegraham - Tuesday, August 6, 2013 - link
*cough* it may be undercut on the front end but maintenance is a typical Oracle "grab you by the chestnuts" type thing.Frallan - Wednesday, August 7, 2013 - link
More like "grab you by the chestnuts - pull until they rips loose and shove em up where they don't belong" - type of thing...davegraham - Wednesday, August 7, 2013 - link
I was being nice. ;)equals42 - Saturday, August 17, 2013 - link
And perhaps lock you into Larry's platform so he can extract his tribute for Oracle software? I think I've paid for a week of vacation on Ellison's Hawaiian island.Everybody gets their money to appease shareholders somehow. Either maintenance, software, hardware or whatever.
Brutalizer - Monday, August 5, 2013 - link
Discs have grown bigger, but not faster. Also, they are not safer nor more resilient to data corruption. Large amounts of data will have data corruption. The more data, the more corruption. NetApp has some studies on this. You need new solutions that are designed from the ground up to combat data corruption. Research papers shows that ntfs, ext, etc and hardware raid are vulnerable to data corruption. Research papers also show that ZFS do protect against data corruption. You find all papers on wikipedia article on zfs, including papers from NetApp.Guspaz - Monday, August 5, 2013 - link
It's worth pointing out, though, that enterprise use of ZFS should always use ECC RAM and disk controllers that properly report when data has actually been written to the disk. For home use, neither are really required.