ZFS - Building, Testing, and Benchmarking
by Matt Breitbach on October 5, 2010 4:33 PM EST- Posted in
- IT Computing
- Linux
- NAS
- Nexenta
- ZFS
Promise M610i
The Promise M610i has been our go-to unit of choice for the last several years in our datacenter. The M610i is a hardware based iSCSI/SATA storage unit that allows you to build your own
We've found them to be reliable, inexpensive, and they perform well for the price point. Over the years we've populated Promise systems with everything from 250GB SATA drives to 1TB SATA drives and everything in between. The performance has remained relatively static though due to the static spindle count and 7200RPM rotating speed of those spindles.
The Promise systems incorporate RAID 0,1,5,6,10, and 1E (a form of RAID10 that allows you to use an odd number of drives). They are hardware controller based, and feature dual gigabit Ethernet ports that can be bonded together. It also incorporates a web-based management interface, automatic notifications, and a host of LED's that indicate power, activity, and failed drives.
For someone that is just starting out in the SAN world the M610i is a very attractive option with little experience necessary. The only drawbacks are when you want to expand the units or if you want better caching. The Promise system allows for a maximum of 2GB of RAM for caching, so if you want additional caching you'll have to shell out for a much more expensive unit. The Promise unit does not allow for adding additional JBOD enclosures. This limits you to a maximum of 16 spindles per system. We would have loved to continue using the M610i's if we could increase the spindle count.
Overall our experiences with the M610i units have been very good. We plan on doing an in-depth review of one of our M610i units at a later date to give a little bit better insight into the management and feature set of the units.
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diamondsw2 - Tuesday, October 5, 2010 - link
You're not doing your readers any favors by conflating the terms NAS and SAN. NAS devices (such as what you've described here) are Network Attached Storage, accessed over Ethernet, and usually via fileshares (NFS, CIFS, even AFP) with file-level access. SAN is Storage Area Network, nearly always implemented with Fibre Channel, and offers block-level access. About the only gray area is that iSCSI allows block-level access to a NAS, but that doesn't magically turn it into a SAN with a storage fabric.Honestly, given the problems I've seen with NAS devices and the burden a well-designed one will put on a switch backplane, I just don't see the point for anything outside the smallest installations where the storage is tied to a handful of servers. By the time you have a NAS set up *well* you're inevitably going to start taxing your switches, which leads to setting up dedicated storage switches, which means... you might as well have set up a real SAN with 8Gbps fibre channel and been done with it.
NAS is great for home use - no special hardware and cabling, and options as cheap as you want to go - but it's a pretty poor way to handle centralized storage in the datacenter.
cdillon - Tuesday, October 5, 2010 - link
The terms NAS and SAN have become rightfully mixed, because modern storage appliances can do the jobs of both. Add some FC HBAs to the above ZFS storage system and create some FC Targets using Comstar in OpenSolaris or Nexenta and guess what? You've got a "SAN" box. Nexenta can even do active/active failover and everything else that makes it worthy of being called a true "Enterprise SAN" solution.I like our FC SAN here, but holy cow is it expensive, and its not getting any cheaper as time goes on. I foresee iSCSI via plain 10G Ethernet and also FCoE (which is 10G Ethernet + FC sharing the same physical HBA and data link) completely taking over the Fibre Channel market within the next decade, which will only serve to completely erase the line between "NAS" and "SAN".
mbreitba - Tuesday, October 5, 2010 - link
The systems as configured in this article are block level storage devices accessed over a gigabit network using iSCSI. I would strongly consider that a SAN device over a NAS device. Also, the storage network is segregated onto a separate network already, isolated from the primary network.We also backed this device with 20Gbps InfiniBand, but had issues getting the IB network stable, so we did not include it in the article.
Maveric007 - Tuesday, October 5, 2010 - link
I find iscsi is closer to a NAS then a SAN to be honest. The performance difference between iscsi and san are much further away then iscsi and nas.Mattbreitbach - Tuesday, October 5, 2010 - link
iSCSI is block based storage, NAS is file based. The transport used is irrelevent. We could use iSCSI over 10GbE, or over InfiniBand, which would increase the performance significantly, and probably exceed what is available on the most expensive 8Gb FC available.mino - Tuesday, October 5, 2010 - link
You are confusing the NAS vs. SAN terminology with the interconnects terminology and vice versa.SAN, NAS, DAS ... are abstract methods how a data client accesses the stored data.
--Network Attached Storage (NAS), per definition, is an file/entity-based data storage solution.
- - - It is _usually_but_not_necessarily_ connected to a general-purpose data network
--Storage Area Network(SAN), per definition, is a block-access-based data storage solution.
- - - It is _usually_but_not_necessarily_THE_ dedicated data network.
Ethernet, FC, Infiniband, ... are physical data conduits, they are the ones who define in which PERFORMANCE class a solution belongs
iSCSI, SAS, FC, NFS, CIFS ... are logical conduits, they are the ones who define in which FEATURE CLASS a solution belongs
Today, most storage appliances allow for multiple ways to access the data, many of the simultaneously.
Therefore, presently:
Calling a storage appliance, of whatever type, a "SAN" is pure jargon.
- It has nothing to do with the device "being" a SAN per se
Calling an appliance, of whatever type, a "NAS" means it is/will be used in the NAS role.
- It has nothing to do with the device "being" a NAS per se.
mkruer - Tuesday, October 5, 2010 - link
I think there needs to be a new term called SANNAS or snaz short for snazzy.mmrezaie - Wednesday, October 6, 2010 - link
Thanks, I learned a lot.signal-lost - Friday, October 8, 2010 - link
Depends on the hardware sir.My iSCSI Datacore SAN, pushes 20k iops for the same reason that their ZFS does it (Ram cacheing).
Fibre Channel SANs will always outperform iSCSI run over crappy switching.
Currently Fibre Channel maxes out at 8Gbps in most arrays. Even with MPIO, your better off with an iSCSI system and 10/40Gbps Ethernet if you do it right. Much cheaper, and you don't have to learn an entire new networking model (Fibre Channel or Infiniband).
MGSsancho - Tuesday, October 5, 2010 - link
while technically a SAN you can easily make it a NAS with a simple zfs set sharesmb=on as I am sure you are aware.