Friday, September 18, 2015

12,290,000 V.92 dial-up modems...

It's that time of year for a new fast file system.

Here's a single box teaser with a pair of disks that we are building...
echo 1 > /proc/sys/vm/swappiness

mdadm -C /dev/md0 --level=raid0 --raid-devices=2 /dev/disk0 /dev/disk1

mke2fs -E nodiscard /dev/md0

mount /dev/md0 /mnt/test

time dd if=/dev/zero of=/mnt/test/cuff1.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff2.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff3.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff4.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff5.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff6.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff7.dat bs=1024k count=100000 oflag=direct &
time dd if=/dev/zero of=/mnt/test/cuff8.dat bs=1024k count=100000 oflag=direct &

du -sh /mnt/test/cuff*
98G     /mnt/test/cuff1.dat
98G     /mnt/test/cuff2.dat
98G     /mnt/test/cuff3.dat
98G     /mnt/test/cuff4.dat
98G     /mnt/test/cuff5.dat
98G     /mnt/test/cuff6.dat
98G     /mnt/test/cuff7.dat
98G     /mnt/test/cuff8.dat

Gives me this for writing out about 0.8 of a terabyte in parallel:

Eight threads @ 3.6GB/s

104857600000 bytes (105 GB) copied, 233.532 s, 449 MB/s
104857600000 bytes (105 GB) copied, 233.652 s, 447 MB/s
104857600000 bytes (105 GB) copied, 233.671 s, 449 MB/s
104857600000 bytes (105 GB) copied, 233.732 s, 450 MB/s
104857600000 bytes (105 GB) copied, 233.758 s, 449 MB/s
104857600000 bytes (105 GB) copied, 233.658 s, 449 MB/s
104857600000 bytes (105 GB) copied, 233.604 s, 448 MB/s
104857600000 bytes (105 GB) copied, 233.371 s, 449 MB/s


And gives me this for reading it all back in:

Eight threads @ 5.4GB/s

104857600000 bytes (105 GB) copied, 155.801 s, 673 MB/s
104857600000 bytes (105 GB) copied, 155.628 s, 674 MB/s
104857600000 bytes (105 GB) copied, 155.577 s, 674 MB/s
104857600000 bytes (105 GB) copied, 155.526 s, 674 MB/s
104857600000 bytes (105 GB) copied, 155.325 s, 675 MB/s
104857600000 bytes (105 GB) copied, 155.323 s, 675 MB/s
104857600000 bytes (105 GB) copied, 154.346 s, 679 MB/s
104857600000 bytes (105 GB) copied, 153.967 s, 681 MB/s


We have 16 of these "things", with enough IB network attached so should get a 57GB/s write 86GB/s read, or the same bandwidth as twelve million v.92 (56K) dial-up modems.

Yep, this isn't your grandpappys flash disk ;-)


Wednesday, September 9, 2015

IT organizational health...

Scene One: A doctor's office on main campus

Enter stage left: IT leader (ITL)

Doctor: "Hello, ITL please do take a seat..."

ITL: "Hello Doctor, I can't thank you enough for taking time to see me for my annual organizational health and performance review!"

Doctor: "No problem ITL, wonderful to see you again. However, I do have some rather unfortunate news about your overall organizational health I'm afraid..."

ITL: "Yes? That's interesting because since last year when we last spoke, we've been making significant strides to improve our overall organizational health. For example, we've hired many external consultants and project managers who have been helping us not only eat better and exercise more, but also help us spend all our money and manage our deliverables and projects with key stakeholders!"

Doctor: "Well I'm not sure quite how to put this..."

ITL: "Go on, I'm listening"

Doctor: "Well. It's the right arm see. It's rotten"

ITL: "Really? It looks fine to me. In fact, last year we gave right arm 10 out of 10 in its performance review - a stella all round performer is right arm. We rely on right arm most heavily for a great number of tasks!"

Doctor: "Well, I don't know what else to say, but it's rotten. It's also kinda ruining the rest of the organization for you I'm afraid"

ITL: "Wow - so ok then, what do you suggest we do with this whole right arm situation?"

Doctor: "It's going to have to come off I'm afraid. Nothing else for it, we will simply have to remove it"

ITL: "Well. The leadership team are very fond of right arm. We all look to right arm as a constant source of support..."

Doctor: "I understand, but right arm is the root cause of all of the organizational health issues you are facing. It simply just has to be removed, and replaced with a better quality right arm. Don't worry we have done this procedure a number of times, it's mostly painless and the new arm... well I'm sure you will be most impressed with it!"

ITL: "I'm slightly worried we will not complete a few of our projects without right arm, but I'm willing to compromise some. You've also shown me that the current right arm maybe isn't quite as useful as we thought it was. So if we are to remove right arm..."

Doctor: "... and then replace right arm! We can't just remove it, that would end very poorly!"

ITL: "....whatever, anyway... I will want to reinvest the cost savings of running this whole right arm department. So, how about instead of these expensive solutions involving replacing right arm we simply recruit two more left feet to help out while you work on this whole right arm issue?"

Doctor: "Addition of two left feet may further compromise the stability of your organization. I would strongly recommend against this two left feet approach, especially if you cut off your right arm..."

ITL: "I read in the New York Times that organizations with two left feet are far more agile, I think that was what the article said, I did read it rather quickly. However to me, it sounds like if we remove this whole right arm situation, then the best idea would be to immediately move the budget from the right arm department and hire an additional left foot at once. I've heard from the left foot department that they are terribly understaffed, and could really do with additional support"

Doctor: "So quick question while we are on this left foot topic..."

ITL: "Sure what is it?"

Doctor: "Assume we do hire this additional left foot. And let's also assume as the New York Times article suggests it all works splendidly, and that things don't all just simply just fall over..."

ITL: "Yes?"

Doctor: "What do you suggest we do with the existing right foot department?"

ITL: "We probably ought to have outsourced right foot activities to an off shore service years ago! I hear many IT leaders are doing this. Also the feedback from the left foot group is that right foot never really helped them so much. Least in anyway that they could see. The left foot department have also been advocating we hire more left feet for a while now"

Doctor: "So you think that removing your right arm, having two left feet, and outsourcing all your right foot operations is going to be a good idea for the organization health as a whole?"

ITL: "I really do think so. Doctor, I just can't thank you enough! I love these little annual chats we have. See you next year! Cheerio!"



Doctor: "I can't even, I simply just can't..."

(fade to black)



[any opinions here are all mine, and have absolutely nothing to do with my employer]
(c) 2011 James Cuff