devil in the details
I thought something was up when the "Number of files systems" was "single namespace", and they mention the clients mounting 24 different file systems from 10 different IPs, 240 file systems per client?
"For UAR compliance, each flexible volume was mapped to a subdirectory of the global namespace under root (/data1,/data2,...,/data24). Each volume was accessed over all data network interfaces (ip addresses ip1...ip24) such that each volume had a unique mount point on each node. This ensured that 1/24th of the total access on each node was done through a local interface and 23/24th of the total access was done through interfaces which were remote to the node the volume resides on. For these remote accesses, data traversed the cluster network. There were a total of 24 IP addresses available for data access, one per node. Each client mounted all 24 volumes using 10 different target IP addresses for a total of 240 mount points. The ten IP addresses selected per client for mounting each volume was done in a round-robin manner from the list of 24 IP addresses such that each successive client used the next ten IP addresses in the series. For example LG1 was assigned the following mount-point list: ip1:/data1, ip2:/data1,...,ip10:/data1,ip1:/data2,...,ip10:/data2,...,ip1:/data24,...,ip10:/data24. LG2 was assigned the following mount-point list picking up next IP adress in the list for each volume:ip11:/data1,ip12:/data1,...,ip20:/data1,...,ip11:/data24,...,ip20:/data24. LG3 continued from the next IP address circling back to the start of the series once the last IP was reached: ip21:/data1,..,ip24:/data1,ip1:/data1,..,ip6:/data1,...,ip21:/data24,..,ip24:/data24,ip1:/data24,..,ip6:/data24. This was done for all 36 clients. This ensured that data access to every volume was uniformly distributed across all clients and target IP addresses. The volumes were striped evenly across all the disks in the aggregate using all the SAS adapters connected to storage backend. "
I wish SPEC SFS had the same disclosure as SPC-1 (esp wrt pricing), but it still has some interesting tidbits.
The real story is of course the flash cache, 12TB of it is where the performance is of course coming from, too bad(for them) their 'cluster mode' isn't as good as the competition. I do not see Isilon short stroking in their SFS results(as I believe was mentioned in the article) but it does appear that NetApp is, having exported only half of the capacity of the system to the clients.
Isilon is exporting 3 times more usable storage to the clients than NetApp.
Wonder what Isilon would get if they ran their test with RAID 10 instead of RAID 5 13+1 (ugh!!) - I'm thinking greatly improved write performance and doing parallel reads on both members of the RAID mirror for increased read performance. Isilon was also using 10k RPM disks, bump it to 15k RPM and RAID 10 just for shits & grins and see what the results are! I would expect at least say a 40% increase in performance (at least for the disks) ? Whether or not the controllers can handle that is another question.
Why anyone would use RAID 5 or RAID 6 when I/O is the most critical thing (as is in these tests) boggles my mind. I know NetApp has self imposed limitations of RAID 6 on their platform, another boggle the mind thing, I don't know if Isilon does the same, I guess I should fire off an email to one of my friends ad Isilon and find out.
With NetApp only exporting half of their usable storage it would make a lot more sense to do RAID 10 there too(this IS an I/O test after all), if they supported it, running RAID DP on 450GB 15k RPM disks is a waste, simply put, the risk of a double disk failure is very small with that spindle RPM and disk size. RAID DP certainly makes sense if your running 15+2 on 2TB SATA disks by contrast when using old style "whole disk" based RAID schemes anyways.
Could NetApp have pushed the I/O numbers higher? The 6240 tested tops out at 6TB of flash cache per controller and the SFS test had only 512GB per controller, maybe 512GB was enough given the workload(or does that mean the controller was tapped out with 512GB), I don't know.