Continuing my shameless promotion of the server_stats command, on later DART, you can see all of your I/O breakdowns on the disk volumes
The store.diskVolume statpath has a pile of possibly useful stats. You can export this to .csv and chart, to see your I/O performance. While it doesn't tell you the limits, it can characterize the data you see in Celerra Monitor, and put it all in context.
This command will list a variety of statistics within the store.diskVolume statpath. server_stats server_2 -info will list all statpaths and variables, which you might want to pipe into a file, to list all of the current statistics groups on your Celerra or VNX.
I tried server_stats server_2 -info store.diskVolume it gave me looks like disk volume number .
name = store.diskVolume description = Per disk volume statistics type = Set member_stats = store.diskVolume.ALL-ELEMENTS.currentQueueDepth,store.diskVolume.ALL-ELEMENTS.reads,store.diskVolume.ALL-ELEMENTS.readBytes,store.diskVolume.ALL-ELEMENTS.readSizeAvg,store.diskVolume.ALL-ELEMENTS.writes,store.diskVolume.ALL-ELEMENTS.writeBytes,store.diskVolume.ALL-ELEMENTS.writeSizeAvg,store.diskVolume.ALL-ELEMENTS.util member_elements = store.diskVolume.root_disk,store.diskVolume.root_ldisk,store.diskVolume.NBS5,store.diskVolume.NBS6,store.diskVolume.d7,store.diskVolume.d8,store.diskVolume.d9,store.diskVolume.d10,store.diskVolume.d11,store.diskVolume.d16,store.diskVolume.d12,store.diskVolume.d17,store.diskVolume.d13,store.diskVolume.d18,store.diskVolume.d29,store.diskVolume.d19,store.diskVolume.d31,store.diskVolume.d20,store.diskVolume.d33,store.diskVolume.d30,store.diskVolume.d35,store.diskVolume.d32,store.diskVolume.d37,store.diskVolume.d34,store.diskVolume.d39,store.diskVolume.d36,store.diskVolume.d40,store.diskVolume.d38,store.diskVolume.d41,store.diskVolume.d42,store.diskVolume.d47,store.diskVolume.d48 member_of =
Yes - this the proper output of the command. This show your all of the available per-volume stastistics available on your Celerra. You can work through all of the various monitor groups in server_stats and get more information. Since the variables change, based on how many filesystems, disks and metavolumes you have, you have to run the server_stats server_2 -info <stat_path>command to get all of the possible variables and combinations.
Here's some ouptut for store.diskVolume:
$ server_stats server_2 -monitor store.diskVolume.ALL-ELEMENTS -interval 1 -te no
The word-wrapping kills the output, but you're looking at the read/write performance for each disk device used by the Celerra. It's hard to see the columns, but the 'Util %" column is wrapped around to the first spot. This is the utilization of the particular disk device. Notice the Queue Depth column? It's "0" for every filesystem - there are no outstanding I/Os in the queue waiting to go to disk. On your own system, you can look at this output and write it out as .CSV file format, import into Excel and graph the results. If you take this output during peak usage, you can see how the backend disk of the Celerra is handling your I/O requests.
store.diskVolume is one of many stastistic paths. If you really want to see what you can collect, try server_stats server_2 -info store > store.statpaths.txt; cat statpaths.txt. This will write out a file with all of the storage statpaths on your system to a text file. Go through each statpath with server_stats server_2 -monitor to see what statistics you can observe. A good approach is collect data during peak and off-peak usage, and use the results to gauge the "envelope" of your system.
If the backend is having difficulty handling your I/O, you'll start to see queued I/O showing in the aforementioned output. Write penalty from RAID5 and RAID6 parity operations generally aren't visible here, unless the backend is having difficulty - again, you'll see it as queued I/O. Unless the backend is really misconfigured - unbalanced SP usage, overloaded buses, mixed drive types in RAID groups, etc. - RAID parity writes should never be an issue. More often, it'slikely that the backend does not have enough disk to absorb the IOPs. Sometimes, people mistake this for a parity issue.
Some of other statpaths, store.diskVolume.ALL-ELEMENTS.util and store.diskVolume.ALL-ELEMENTS.avgServiceTime, provide more detail on backend performance, relative to the disks used by the Celerra. During idle times, you can characterize utilization and average service time, then compare them under peak load.
Hi, does this command just work on celerra OS 6.0. I tried it on 5.6 but it came back with an error? Also are these real figures of IOPS/sec of dvols from cache on the array or spindles.
Rainer_EMC
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Posted May 20th, 2011 06:00
Difficult to say since it doesnt say block size and which I/Os