random complexity

with a side of crazy

Posts Tagged 'blog'

Another fork in the road

It's been ages and ages since I've really felt like writing a post and I'm sure the neglect here is obvious. Plenty has gone on in the interim, well at on and off actually. I have a few things I feel the need to write about, and due to the varied topics will try to keep them in separate posts.

I'll start off with the one that reoccurs periodically over the years, and that is the persistent feeling of being stuck at a fork in the road. To stay or to go. If stay how to fix whats wrong, and if go, where to and why. The key bit is the need for change. This has come up often enough that I know it's a temporary thing, and the resulting action is just a distraction, an abberation from the mean. It's a combination of a motivation/reward thing and a happiness thing.

The other thing is it's always on multiple fronts concurrently. If it was just one thing it's usually easy to figure out a way forward and just plod on. When it's more than one it's difficult to pick what to work on first or even spot the interdependencies between them. Correlation doesn't imply causality, it could just be dumb luck.

Previously I've tried to escape it by trying new things and simplifying. Don't take on too much at once. Focus on what matters. That sort of thing. The things you own end up owning you. The only snag with all of that is it can be difficult to find motivation to adjust course. It's like life and routine is a large ship, and trying to influence it's direction takes sustained directed effort. Simplifying takes dedication to work through something, but it's frequently worth it and is an ongoing process. Clutter feeds itself both physically and logically. Likewise changes to routine can be beneficial for many ways and also takes dedication and motivation.

The snag I've currently hit is mostly a lack of direction and motivation. Sticking in a holding pattern doesn't achieve anything and just seems to fuel the downward spiral. It's been same old-same old for too long and somethings going to give.

Fork in the road (from the muppets)

Disk life spans over a span of life

Oops, I found this in my upcoming posts folder when I thought I'd posted it already. Some of the dates might be off as I wrote it a year ago and only casually updated the timings now.

Over the years there's been quite a few articles on the life spans of consumer grade sata drives. The most notable I can recall are the ones by Google from a few years ago and some more recent ones from Backblaze and another from Backblaze (they seem to be posting quarterly now). All of those articles cover huge fleets of disks over several years maintained in computer room environments. They're excellent reads and produce some interesting results. More recently a similar themed paper about flash storage has come out at FAST 16 conference.

I've kept some rough notes on my disk fleet over the years and recently noted the following in my fleet of 2TB Western Digital Greens. Lots of people hated the green power series citing various issues with the spin down or firmware issues. I've run mine (mostly) flawlessly on solaris (openindiania and now illumos) for years, and went from 1TB greens to 2TB and later 3TB's. To avoid beating around the bush I'll focus only on the 2TB drives since this is where I have the most relevant data.

  • My initial purchase was 8 drives in April 2010 which grew over the years to a system of 22 disks at the end.
  • Just under a year later (Feb 2011) I bought 2 more, most likely to replace a failure and keep a spare on hand. The exact use I never recorded.
  • Another year later (Jan 2012) I bought 2 more;
  • 3 months later (April 2012) another 2. Around this time I expanded from an 8 disk system to 12, so it's reasonable to think I'd had either 2 failures by this point or a failure and a cold spare (again no record).
  • 5 Months later (Sept 2012) I bought another 8 drives, so this would have coincided with my expansion into a 24 bay case. Around here I switched to triple parity (raidz3) with 19 disks total (aimed for a correct zfs stripe size of a power of two plus parity, for performance reasons).
  • 5 Months later again (Feb 2013) another 2 disks. Around here switched from raidz3 to 2 raidgroups of raidz2, 20 disks total. The performance of the larger stripe raidz3 was too low, and adding one more disk allowed me to half the raid group size.
  • 9 Months later (Nov 2013) 3 more disks. Around here, expanded out to 2 raidgroups of 11 totalling 22 disks.
  • 4 Months later (March 2014) 4 more disks. These were the last 2TB drives I bought, due to price difference to 3TB.
  • 12 months later (March 2015) 2x 3TB disks, 1 to replace a 2TB failure and a cold spare.

As of March 2014 I had 4 disks showing 35000 power on hours, so they would have been from that initial purchase. Not bad having half of them still running nearly 4 years later.

The final 4x 2TB disks were purchased to replace the disks from the 35000 hour set. Those 4 disks had average request service times 6-10 times slower than the rest - solid 12ms vs 1-2ms, and that was a serious performance impact, probably due to bad sector relocation causing additional seeks. Yes that's not a typo, 1-2ms on a green drive is my average, sounds odd right. In theory the rotational speed dictates the worst case seek times, however in practice on my system this is rarely seen even under medium load. Under heavy load it all goes pear shaped because these are consumer grade sata drives spinning at under 7200rpm (WD greens spin speed varies by model).

The other observation there is I switched from fewer larger raidgroups to more smaller, this is for performance reasons mainly as large raidgroups in zfs seem to perform poorly, even with plenty of ram and sizable l2arc. This theory was validated with my 3TB box which uses 3 smaller raidgroups and performs very well.

In all of this time I've removed 3 of the 2TB disks for developing sector read/write errors (visible and repaired by zfs) before they actually failed. My 3TB's haven't been as good, however I don't leave them spinning 24x7. They were all pre-owned drives with an average drive age of 12000 hours when I got them - they're a backup box which I use for offline data protection and an excellent way to reshape my zpools by dumping and reloading (over a 10G cross over link).

Fast forward this story to November 2015 and I've upgraded the 2TB's to 6TB's as I'd decided the 8TB non archive drives were too far away to wait for. I also switched to the WD Red NAS drives and they also work flawlessly with illumos/zfs. Took a few days to resync back from the archive. Over the following 18 months one of the 6TB's has developed bad sectors and I'll be looking into swapping that out soon if I can figure out the warranty process.

The 3TB cold spare which remains spare to this day, now 2 years old. I've had only 2 of the 3TB's fail on me so far. If my story and counting is correct I've had only 3 of the 31x 2TB drives fail on me, 3 replaced for developing bad sectors and 4 replaced for performance going to crap, over a total of 5.6 years. ... let me rainman that ... 6.25% cumulative failure rate, 1.11% annual failure rate. That's at the low end of failures for 2TB WD's that Backblaze saw in their stats (and theirs weren't green power drives).

It will be interesting to see how the 6TB's last over a 5 year timeframe. So much is due to change in this space over the next 1-2 years in enterprise, and 2-4 years (at most) in the consumer space. With large capacity SSD's coming to market in the enterprise space and larger sata archive drives. Hopefully we'll see cloud prices drop further too.

Spinning Disk

Brief 2017 Update

So 14 months ago I posted a 2016 update saying stay tuned. I guess no one is left waiting now. Given the gap from that post to the previous too, I had failed at the saying if you don't start, you'll never succeed quite clearly.

This time however I have stuff to write about. But will break the ice with a summary one and then get into the thick of it over the next few days (yeah yeah).

As with last time, that post referenced Fedora 23 and now Fedora 26 has just been released - must be time to upgrade.

Other things have changed too;

  • upgraded ESX (6 to 6.5)
  • switched to vSAN too, now on version 6.6
  • installed a 10G switch for ESX and storage to use
  • upgraded all my boxes a few times
  • Ansible everything project continued to new levels
  • LOTS of tv of course, it's my staple for downtime
  • fair bit of gym, which went up and then down and now out.
  • fair bit of riding, also went up and down and now trying to go up again.
  • no travel anywhere, not even for work. I don't think I've been futher away from home than Pinjarra road since then.

But this time I have written more and will post over the next few weeks.

Fedora 26 watercolour theme

2016 Update

So it's been a long time since I last posted. Much has changed and happened in the past 21 months. Gee has it been that long. My last post referenced Fedora 20 and now 23 is nearly 7 months old, with 24 about a month away.

Quick summary would be;

  • moved house
  • some personal stuff
  • changed jobs (big miner to big miner)
  • some family stuff
  • changed clouds (rackspace to google)
  • changed drives (2TB -> 6TB)
  • upgraded ESX (5.5 to 6)
  • upgraded all my boxes too
  • Ansible everything project
  • LOTS of tv
  • fair bit of gym
  • fair bit of riding
  • Adelaide trip

That'll do for now. I should probably make a whole series of posts about ansible and what I've done with it, but first I think I've got another vmware related post cooking away nearly ready to serve.

Please Stand By

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