Solved

sysbench slow performance of new 18 disk raid 1+0

Posted on 2009-03-31
6
1,366 Views
Last Modified: 2013-11-14
We have recently purchased the following hardware.
HP DL380 8cores 32GB 2x72 10k sas drives
HP MSA70 array with 18 sas 146 10K dives

We upgrading our MYSQL database hardware.  I have the array configured  the array as a 18 disk raid 10 with 100 write cache on.

I am running the following sysbench test:

sysbench --test=fileio --init-rng=1 --file-total-size=8G --file-num=4 --max-time=120 --max-requests=10000000 --file-rw-ratio=1.5 --file-fsync-freq=on  --file-test-mode=rndwr --file-extra-flags=direct --num-threads=32 prepare

sysbench --test=fileio --init-rng=1 --file-total-size=8G --file-num=4 --max-time=120 --max-requests=10000000 --file-rw-ratio=1.5 --file-fsync-freq=on  --file-test-mode=rndwr --file-extra-flags=direct --num-threads=32 run

And getting the flowing results:
18disks raid10 Read 0b  Written 9.9037Gb  Total transferred 9.9037Gb (84.467Mb/sec)    5405.88 Requests/sec executed

I get 5400 random writes per second on the 18 disks raid 10.  Our dba is saying that he is getting 10K on a 4 disk raid10.  I believe  I am getting the correct performance out of this array. But I do not have a real base line.  I am looking for benchmarks of similar systems `16-20 disk raid 10 with the same sysbench command I ran above.

I am also looking for any configuration problems that would lead to 4disks running 2 times as fast as 18 disks.
Thank You
Martin

0
Comment
Question by:martin_2110
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
6 Comments
 
LVL 55

Accepted Solution

by:
andyalder earned 500 total points
ID: 24037490
5400 IOPS sounds pretty good to me, 600 IOPS per disk so some is being met from cache - you'll get about 170 IOPS per disk at a push. Not sure how he's getting 10K IOPS on 4 disks, that's 5000 IOPS for a single disk which is clearly impossible so it has to be coming from RAM. It can't even be coming from controller battery backed RAM if you are using an 8GB file size since there aren't any PCI controllers with that much RAM on them.

Not sure how rndwr and file-rw-ratio act in combination, I guess it ignores file-rw-ratio.
0
 
LVL 7

Author Comment

by:martin_2110
ID: 24041824
Thanks andy. Do you know a good benchmark that will defeat caching? I would like a linux benchmark to give me the actual IOPS per drive?
0
 
LVL 7

Author Comment

by:martin_2110
ID: 24041845
Far as the file-rw-ratio it is ignored.
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 55

Expert Comment

by:andyalder
ID: 24043135
Not really a Linux engineer but I presume you can do the same as I do using IOmeter for Windows. Partition the drive into a number of slices (say 20 of them) and then run 20 seperate instances of sysbench each using a file on its own partition. This defeats the cache fairly well because instead of an single 8GB file there are 20 * 8GB files spread across the disk. It also forces long seeks; your developer might be using big SATA disks in his PC and you can almost get 8GB on a single track on the outside of the platter. You'd obviously have to drop num-threads down to one per instance.

If he is using big SATAs then get him to run the tests for an hour or so, they go into write-verify mode when they get hot which really slows them down. Your little SAS disks are designed for 100% duty cycle so they don't slow down like that.
0
 
LVL 7

Author Closing Comment

by:martin_2110
ID: 31565045
Thank you.
0
 
LVL 55

Expert Comment

by:andyalder
ID: 24043481
Thanks :)

I'd like to see the results of re-running the tests on the two arrays so will be grateful if you can post them sfter re-running. If nothing else it will help others because as you must have observed, there aren't many publically accessible benchmarks out there.
0

Featured Post

Get Actionable Data from Your Monitoring Solution

Your communication platform is only as good as the relevance of the information you send. Ensure your alerts get to the right people every time with actionable responses. Create escalation rules that ensure everyone follows the process and nothing is left to chance.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Google Drive is extremely cheap offsite storage, and it's even possible to get extra storage for free for two years.  You can use the free account 15GB, and if you have an Android device..when you install Google Drive for the first time it will give…
In the first part of this tutorial we will cover the prerequisites for installing SQL Server vNext on Linux.
This video teaches viewers how to encrypt an external drive that requires a password to read and edit the drive. All tasks are done in Disk Utility. Plug in the external drive you wish to encrypt: Make sure all previous data on the drive has been …
This Micro Tutorial will teach you how to reformat your flash drive. Sometimes your flash drive may have issues carrying files so this will completely restore it to manufacturing settings. Make sure to backup all files before reformatting. This w…

696 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question