SATA/SAS RAID Cards Don’t Perform
We’ve got a little project running to build out our new cloud environment. More on that later. The first problem is the hardware, which is left over from another project. Except that project never bought RAID cards for the hardware, even though they did buy disks.
The enclosures are 2u SuperMicro machines that support 12 3.5″ disks, but require low profile expansio cards. The disks are 1TB Western Digital WD1001FALS. We have this new policy of testing hardware before we put it into production to make sure that something isn’t seriously wrong with it, so we started out by benchmarking single drive performance on the crummy onboard IC10H SATA controller.
Our testing methodology is basic. We’re using fio 1.58 and running a mixed read/write across 1GB of files, in order to exceed any cache. 8 of the drives will be in a RAID0 (yes, I know, but we’re basically doing RAIM — Redundant Array of Independent Machines and it doesn’t matter if we lose a drive…) and the remaining 4 drives will be used for various system tasks. As a result, we evaluated 16, 12, and 8 port cards — we can have the 4 drives used for various cloud system tasks on the onboard, and the bulk storage on the 8 port card, and tried to evaluate one from each major manufacturer where we could.
We used this FIO configuration file for the testing.
[global]
directory=/mnt/glusterfs
lockfile=readwrite
ioengine=libaio
iodepth=32
rw=randrw
numjobs=8
[file]
filesize=16-8k/8M-512M
blocksize_range=64k-1M
size=1GiB
nrfiles=50
openfiles=8
runtime=900
Many thanks, by the way, to Joe of Scalable Informatics fame, who helped me with the mostly undocumented fio configuration and interpreting the results. The intent was to really load down the system, as we’ll occasionally see performance at it’s worst while we’re rebalancing GlusterFS nodes.
All drives as tested were formatted with XFS, and XFS was given the proper parameters to match the RAID stripe size, block size, and RAID member count. Stripe size did not affect performance, and misconfiguring XFS only knocked a few MB/S off of the performance. The systems being tested were based on Debian Squeeze or Wheezy.
The bare drive performance was … barely acceptable. These drives are just not fast. We have several hundred of them sitting around unused at this point, but they’re just not fast. I’m aware of this, and aware that if I wanted faster drives, I would need to … buy faster drives. That doesn’t change that the results of the single drive on the on-board IC10H were faster than a hardware RAID0 array, independent of card manufacturer. As expected, a RAID0 of four drives on the motherboard did perform better than the single drive.
The number to pay attention to here is the “aggrb” number, which is the Aggregate Bandwidth (I’m assuming average?) of the Read and Write performance.
Single Drive
Run status group 0 (all jobs):
READ: io=3899.1MB, aggrb=43205KB/s, minb=5389KB/s, maxb=6518KB/s, mint=79407msec, maxt=92432msec
WRITE: io=3854.2MB, aggrb=42698KB/s, minb=5411KB/s, maxb=6329KB/s, mint=79407msec, maxt=92432msecDisk stats (read/write):
sdb: ios=11269/116, merge=0/4, ticks=990700/7375576, in_queue=11339444, util=99.99%
four-drive md RAID0 on motherboard
READ: io=3865.4MB, aggrb=58034KB/s, minb=7693KB/s, maxb=8684KB/s, mint=56725msec, maxt=68203msec
WRITE: io=3888.4MB, aggrb=58379KB/s, minb=7188KB/s, maxb=9407KB/s, mint=56725msec, maxt=68203msec
Disk stats (read/write):
md3: ios=14434/6379, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=3608/1532, aggrmerge=0/18, aggrticks=174913/2779239, aggrin_queue=3007156, aggrutil=98.52%
sdb: ios=3610/1599, merge=0/15, ticks=162252/1948784, in_queue=2111332, util=91.81%
sdd: ios=3622/1615, merge=0/19, ticks=158384/1409576, in_queue=1568244, util=88.70%
sde: ios=3621/1452, merge=0/23, ticks=210640/4865588, in_queue=5220932, util=98.52%
sdf: ios=3581/1465, merge=0/18, ticks=168376/2893008, in_queue=3128116, util=96.82%
Now, on to the hardware cards.
HighPoint RocketRaid 2740
RAID0, 64kb stripe
Run status group 0 (all jobs):
READ: io=3837.8MB, aggrb=29420KB/s, minb=3727KB/s, maxb=4083KB/s, mint=122403msec, maxt=133571msec
WRITE: io=3903.0MB, aggrb=29921KB/s, minb=3672KB/s, maxb=4227KB/s, mint=122403msec, maxt=133571msecDisk stats (read/write):
sdb: ios=61319/953, merge=0/6219, ticks=7324792/16807752, in_queue=24753304, util=100.00%
Wow! Just to be on the safe side, I put the card in JBOD mode and ran a test against a single disk.
Run status group 0 (all jobs):
READ: io=3928.8MB, aggrb=41145KB/s, minb=5176KB/s, maxb=6050KB/s, mint=85203msec, maxt=97775msec
WRITE: io=3822.0MB, aggrb=40027KB/s, minb=5062KB/s, maxb=5900KB/s, mint=85203msec, maxt=97775msecDisk stats (read/write):
sdc: ios=62770/523, merge=0/3073, ticks=5474732/8123704, in_queue=15781220, util=99.99%
That’s a bit slower, but pretty much rules out the cable or drive being tested — it must be the logic of the card or the driver that’s causing the slowdown.
LSI / SuperMicro AOC-USAS2LP-H8iR
While this card was fastest, we couldn’t get a solid result from FIO no matter how dumbed down the configuration we gave it. The test would run overnight before it finished with an error, after one of the 8 threads was consistently writing to/from disk. I’m not sure if this was a bug in FIO or a bug in the LSI/SuperMicro card, but SuperMicro’s support was so stellar in pointing fingers at LSI that we never resolved the problem. LSI, in turn, referred us to SuperMicro, saying they held no responsibility for cards purchased through the third party. It’s interesting to note that we could reproduce similar results by using LVM striping across 4 drives on any other card. We had so many problems with this card’s BIOS (which has a Windows 3.1-like shell as a configuration tool and doesn’t support USB mice) and drivers (wouldn’t support Debian Wheezy or Linux 3.0) that we just gave up on it.
Areca 1880ixl
Run status group 0 (all jobs):
READ: io=32206MB, aggrb=36641KB/s, minb=4585KB/s, maxb=4788KB/s, mint=900006msec, maxt=900035msec
WRITE: io=31983MB, aggrb=36387KB/s, minb=4534KB/s, maxb=4796KB/s, mint=900006msec, maxt=900035msecDisk stats (read/write):
sdd: ios=108411/106883, merge=0/515, ticks=9122710/8694050, in_queue=17816860, util=100.00%
Out of all of the cards, I liked Areca’s drivers and management interfaces the best.
Adaptec 6805
Run status group 0 (all jobs):
READ: io=3906.8MB, aggrb=41960KB/s, minb=5380KB/s, maxb=5783KB/s, mint=89043msec, maxt=95339msec
WRITE: io=3847.9MB, aggrb=41328KB/s, minb=5085KB/s, maxb=5782KB/s, mint=89043msec, maxt=95339msecDisk stats (read/write):
sdd: ios=19236/19941, merge=0/965090, ticks=1565890/1470100, in_queue=3035980, util=99.96%
Since this card came closest to the single drive performance, we ended up choosing it.
Conclusions
My methodology here is lacking. The few variables that I could control for were different machines/motherboards of the same model, two different cards from the same manufacturer, different 1TB drives, and multiple runs of tests. We ran tests in RAID5 as well. I didn’t publish the RAID5 results here as they were superfluous; just knock 10mb/s or so off of the RAID0 time and you’ve got the RAID5 time. We tried different stripe sizes and different filesystem configurations; with explicitly aligned partitions and without. Nothing seemed to make a difference.
I would expect that any RAID0 array would be faster than a single disk. I would further expect that any cache would improve the performance, even in a heavily loaded random read/write environment. These expectations were proven false. I’m not sure why this is, unless no one else has truly measured performance in a random read/write environment, and people mostly rely on benchmarking tools like bonnie++ that aren’t as brutal about keeping queues flooded and randomizing I/O.
If I were working in a real hardware testing lab, I would move on to test these cards with different motherboards, backplanes, and drives. Unfortunately, I’m not — and this article is the result of 3 months of testing, ordering another card, testing again, tinkering with settings, reading obscure mailing lists, tinkering further with settings, and finally ordering another card in exasperation. I’d welcome someone else’s reproduction or refutation of these results with their own hardware, drives, and cards, a critique of my fio configuration and methodology, and suggestions on optimizing the other variables for improved performance.
Stephen Foskett is running a series about server blades — and as usual for someone who gets a lot of trial equipment to review, he’s pretty bullish on them.
After a few years with blades at my current company, I’m not. Unless you need the density that they offer, they’re probably not worth your time and money — and if you can afford them, you can probably afford to lease another rack or a larger cage.
While Stephen does an excellent job of covering the high points of blades, he skips or glosses over the downsides. The downside is that you re-introduce several single points of failure in the form of the backplane and modules that are plugged into the chassis, and extra management overhead of switches attached to the backplane, and add risk of heat because of the miniaturized and densely packed nature of the components.
Think this is doom-and-gloom? We’ve got a bunch of hardware sitting in a pile that says it isn’t. One of our IBM BladeCenter chassis has only one slot that will work in it — the rest of the slots give you strange PCI bus errors, KVM won’t work, or the management module will fail to connect to the hardware that’s installed properly. Since the blade’s backplane and management modules are a part of the chassis, IBM declined to replace it under our parts-and-labor warranty agreement — they said that we’d have to replace the entire chassis at our cost since the chassis is not a Field Replaceable Unit.
Troubleshooting problems with parts or upgrading parts on individual blades is a chore. Again, many of the parts aren’t technically Field Replaceable Units (and this includes parts like on-blade flash disks), so you’ll need to get out your oddball collection of Torx heads. It’s like laptop repair, with fine ribbons and cooling ducts stitching together byzantine layers of circuit boards. And let’s add another negative in — even if you cool the systems appropriately and your cooling systems aren’t overloaded and don’t ever overload, you still face heat death problems after the term of a normal warranty. Many higher ed institutions are starting to buy on a five year lifespan instead of the traditional three year lifespan, so high density systems like blades or thumpers are not an advisable solution there.
Many blade chassis are limited on expansion module space. Depending on your I/O configuration, you need at least six expansion slots to have some semblance of redundancy — two management modules, two I/O bus (Fiber Channel, Infiniband, 10gbE, SAS, etc.) modules, and two switch (ethernet) modules. The IBM BladeCenter S and E chassis options only support four modules. The higher end newer options, H and HT, support four high-speed and four legacy — keep that in mind when you’re thinking about expanding. Most of the modules only support six ports, which means that you’d need three modules (high speed slots only, of which you have four!) to support a single full-bandwidth fiber channel connection to a server in each of the 14 bays in an BladeCenter H-series — with no redundancy, and no way to expand further. For environments that need both Fiber and Infiniband, you’re pretty much out of luck.
Let’s not forget that each of the modules usually has a management interface of it’s own. The fiber channel modules have a console that you need to manage separately from any other fiber channel interfaces you might have. The switches have a cisco IOS-like interface to them, unless you buy actual Cisco modules for your blade center. Why’s that a hassle? Keep in mind that you need to manage VLAN and trunking assignments and limits on both your core switch and your blade center’s switch.
So: High-bandwidth environments need not apply, since shared connections are the rule instead of the exception. Environments where an addition or switch to a new technology might be managed by adding three or four PCI cards to the affected servers need not apply — your chassis won’t have room for it.
For all of those “Features”, you gain the ability to save some floor space … and you pay a lot more.
Let me introduce to you a new technology called the “40 blade server” — you take a 42U rack, set up appropriate power modules on it, and then plug 40 1U servers and a pair of switches in at the top. Sure, there’s a bit more wire, but that’s easily managed. The 1u servers are individually less expensive than server blades and have a host of nice features — such as independent KVM and individual expansion card slots — that you won’t find in any blade server.
Admittedly, one place we have been very happy with “Bladed” components is our Cisco routers. The ability to hot swap modules and fail between modules is nice — but it’s something that we could manage without; it’s simply a better way to do things in the Cisco world since the price differential isn’t that high and the equipment lifespan is closer to ten years than to three.
But for compute? Heck with that. I see very few environments where blade centers are a good solution compared to a rack of 1u servers.
Dad and I are both hobbyist renovators. Dad has been doing it for about thirty years longer than I have, though, and is a LOT better at it than I am. When I bought my house, he sent me a list of products and notes on them. I’m re-posting here, with some of the discussion edited out, for posterity, reference, and linking purposes. I actually keep a text copy of the entire thing on my phone for reference when I’m away from the internets…
We have a saying in my family — “Ask me how I know!” — which usually means that we’ve screwed something up, bought the cheaper tool or the cheaper product, and ended up regretting it. Each and every one of the below points can be followed with “Ask me how I know!” from personal experience, because I don’t always believe good ol’ Dad either. The below is in completely random order.
- Spackle: MH Ready Patch – Spackle is used for small repairs to drywall, such as picture holes or where you’ve pulled out a molly/plug. MH will stick to lots of things and will harden up well without sagging. It’s solvent based, so it won’t cause problems with oil finishes and can be used on both wood and drywall.
- Caulk: Two products. Polyseamsealis available at Lowe’s and Home Depot and many other places. Unfortunately, Loctite recently bought the parent company, Henkel (also makers of the much beloved PL Premium), so the tub/tile stuff is no longer available in matte and they may have changed the formulation. Outside, we use Sashco Big Stretch Caulk & Seal, 10.5-Ounce, which is pretty amazing stuff. It’s the most elastic caulk I’ve ever seen, but you really have to fill a crack in it — and larger cracks fill better unless you can sort of ‘glue’ the two pieces together. I especially like to use it on Hardi Board/Panel, which shifts a lot in the Texas heat. Once it dries, though, it can only be removed with lacquer thinner, if that.
- Paint: Benjamin Moore. Super Spec is contractor crud, I use a LOT of Regal Aquavelvet, and Aura is amazing with dark or highly pigmented colors. We use Satin Impervo (oil) on trim. I have recently had decent experience with the HGTV and Duration lines of paint from Sherwin, but anything except their top of the line has performed poorly for me both in application and over time.
- Wire Nuts: Use only wire nuts with springs in them, like the tan Ideal ones available at Home Depot. Don’t buy the cheaper mixed bag of Buchanan ones with the different sizes/colors… you’ll spend more time dropping them or having them fall off in the j-box than you will actually screwing them on to wires.
- Screws: Don’t use drywall screws for construction, fencing… or really, anything but hanging drywall. For construction, I put everything together with screws because it makes it WAY easier to take apart later. I’ve done several structural changes to my house and used SPAX screws to hold interior framing together. (I typically use 2 inch or 3 inch screws.) For fences or decks, use fencing or decking screws.
- Paint Brushes: We tend to use Purdy brushes. Remember that you use different brushes for latex and oil; I don’t trust the “all purpose” ones to leave a clean line. My personal favorite brush is a Purdy Cub XL 2″ brush. Wooster brushes are also OK, but I don’t like them anywhere near as much as I like Purdy brushes. Clean them well and they’ll last you a long time.
- Drop Cloths: We put a 3-4 mil plastic drop cloth down with a canvas drop cloth over it. Why? Because without the plastic, the canvas will let the paint soak through. And without the canvas, when you spill or dribble some paint, you will step in it and then track it all over the rest of the house. Ask us how we know…
- Extension cords: Don’t get the cheap 14 or 16 gauge ones. Spend the money for a decent 12 gauge one. You can’t pull enough amps down a 14 gauge one in most cases for the tool to perform properly, and most power tools worth the name are going to pull 10-15 amps under load, not to mention any spikes or high draws.
- Sand Paper: Don’t bother buying Gator. They’re garbage, even the “higher grade” black stuff… the grit doesn’t last long enough and the paper loads up far too easily with dust and other leavings. I have had really, really bad luck with Norton discs leaving horrible dual action orbiter marks because of the “universal” five hole/eight hole design. The Dad-approved product is Mirka sandpaper.
More blog posts along this line coming down the pipe…
RHEL 5 supports XFS out of box
I was trying to figure out how to get XFS working on a RHEL box at work so that we could store more than 16TB on a filesystem, and found Gianpolo Del Matto’s excellent XFS on RHEL tutorial.
And then I found out that most of that mucking around in the kernel build process isn’t necessary.
RHEL5 u6 (at least my copies — note that I have the -xen kernel packages installed, which might affect things) actually has the XFS kernel module in /lib/modules/kernel/fs/xfs — it just doesn’t have the xfsprogs package, and the xfsprogs package is not available via any supported means. I downloaded the xfsprogs srpm from the XFS project page and used rpmbuild to build and install it myself.
Does anyone else in this day and age find it ridiculous that Redhat does not support filesystems larger than 16TB without some form of hackery? I can buy that much disk storage at my local Office Depot.
Note that I’m pretty sure that the mount option ‘inode64′ is required if you’re over 16TB, and that 32-bit NFS clients do not like the inode64 option one tiny bit.
The Economist has had a bunch of articles recently about legal reform and how necessary, but unlikely, it is.
One of the things I love most about science fiction is it’s ability to take an idea like “legal reform” and extrapolate it into a meaningful, personal story to illustrate the need for changes. How would you explain to your ten year old daughter why someone is suing her for the things her ancestors did? Or why she can’t sing along out loud without permission? How would you like it if your baby was sued before he or she was born? If the lawyers get their way, that’s our future.
1 1/2 years as a homeowner and…
So far, in one and one half years as a homeowner, I’ll have spent $25,000 (about 1/5 of my home’s purchase price) on repairs and maintenance.
That only includes receipts that I’ve kept; I have no clue how much I’ve actually spent. Triple the figure if I’d had to include labor costs.
It makes me sick to think that people who bought in stupidly at a peak and don’t have steady employment are getting breaks. Shouldn’t people who work hard successfully get rewarded?
(This post brought to you by NeatDesk, which has managed to collate and report on an unbearable number of receipts in the past few weeks.)
Lesson to all the kids in the audience: Homeownership isn’t for everyone. If you’re not willing to lift a hammer and you have no savings, it’s a trap you’ll never get out of.
When to Jump Ship
If your workplace starts to look like Realtime Worlds (the publisher of APB), then you should definitely have a “Plan B” in the works.
I’m a little delayed with work and consulting stuff, so I haven’t gotten the chance to fully explain why I punched a bunch of holes in my roof yet, because it requires a bunch of diagrams and pictures and stuff. I’ll get to it this weekend.
There’s certain things that I’m perfectly willing to do myself. There’s certain things that I’m willing to pay to have done. And then there’s things that I don’t want to touch, haven’t touched, and probably never will touch. These, I subcontract.
I’m willing to do most things myself. This includes dirty things, like digging holes, messy things, like dropping a ceiling with blown-in insulation, and dirty, messy, pain-in-the ass things like mudding and taping. My reasons vary — sometimes, I’m too cheap to pay someone else to do it, or I want the experience of taking something apart because I discover things (like additional rot and water damage or wiring problems) that I wouldn’t if I hadn’t taken it apart myself.
Things I never, EVER touch are sort of split into two categories. The first is safety, and the second is experience.
Safety-wise, I don’t feel comfortable making hookups with the main gas lines in my house in areas where they’re not accessible — in attics, walls, or ceilings. I’ll do hookups to appliances because you can smell if they spring a leak, but I don’t want it to be my fault if the gas line in my attic springs a leak and no one smells it until the heater clicks on, and KABOOM! I also feel that way about things inside the electrical panel, but having watched this video a few weeks ago might’ve saved me $150 in electrician’s fees… (Then again, the advice I got from him was priceless.)
Experience-wise, I don’t feel comfortable doing roofing modifications myself. For example, I had some turtle vents put in to vent my attic space. I don’t feel comfortable doing anything that requires a particular pace and will get screwed up if it goes wrong. For that reason, I don’t plan to put self-leveling compound on my living room floor myself before I install whichever type of flooring we eventually choose… I’ll have someone do that. I’d hate to pay for the materials twice.
I found one more thing I never want to do (again): Hang drywall on a vaulted ceiling. I paid a couple of friends to help me out with it, but it just isn’t working, so I’m going to end up subcontracting that out. I already wasted about $50 worth of drywall to do it completely wrong; I don’t want to waste any more. I’ll still tape and mud it myself, because I’m good at those things and I want to be responsible for the results.
Side note: You should’ve SEEN the four of us trying to hang the drywall on the ceiling. 5/8 in. drywall is HEAVY (about 40 lbs per 4′x8′ board), and I couldn’t until last week even lift a sheet of it by myself. We spent several hours trying to hang each sheet, and still screwed it up in epic ways that were nearly impossible to correct. I’ve got a new idea for a comedy show on DIY Network: “Gringoes Hang Drywall” Freakin’ HI-larious.
Here’s a few shots from the pilot episode…
Nice detail on that can light, ‘eh?
There’s so much wrong with how we did this, I can’t even begin to describe. First, we cut the angle to the right incorrectly. Second, we didn’t hang it high enough. Third, we didn’t notice how close to the header we were getting, which would’ve meant I was putting a up a lot of scrappy pieces. Third, we weren’t a full factor of four off of the ground, which meant that I couldn’t hang half-sheets where I needed to in order to get efficient use of my materials.
FAIL. I’m letting the professionals do it.
I got my green tag on my electrical rough-in and got permission to “close in” six days after I started. It doesn’t look like much, but this little baby’s the result of about 80 hours of hard labor…
(If you’re doing a renovation with a general contractor, and you don’t see a series of these below your permit as the job progresses, you should ask a lot of questions.)
The “OK to cover up” means that I’ve got permission after this to put insulation over the electrical work I did. The purpose of this inspection was to make sure that I used the right wire and gauge of wire, that I stapled it properly and ran it into the box properly, and that it was connected properly in any junction boxes in the ceiling. The inspector wanted to know where each and every wire went, if I had used grounding screws on the junction boxes I had added to the attic, and if I’d used non-metallic boxes or approved romex grommets where I did use metallic boxes.
Any circuits that you alter while you are doing work are required to be brought up to code. That means that if you tie into, reroute, add wire to, or remove wire from an existing circuit, the whole circuit needs to be brought up to the current code: GFCI outlets or protected circuits in wet areas, arc fault breakers in circuits that run through bedrooms, confirm the # of devices on a circuit… the whole nine yards.
I also installed wired smoke alarms. To pass inspection, I didn’t NEED to, but it was highly suggested that I do so. Code in my area if I were to rent the house requires that there be a wired smoke alarm in each bedroom (defined as an enclosed room with a closet and a window), and a combination wired smoke alarm / carbon monoxide detector in the hallway leading to the bedrooms. Since I do plan to rent at least a room out at some point, I went ahead and installed them so that I’d get it all done at once.
Honestly, I lost the most time through ALL of this to using cheap wire nuts. Beige IDEAL wire nuts work great. Yellow/orange Buchanan ones are crap.
I will need another green tag after completing the insulation, before I can put drywall up.
Insulation. First thing: It’s itchy. Second thing is that it’s a pain in the butt to get it in if you’re installing the batts yourself. Third thing is: At least you can install it yourself without paying the cost per cubic inch that spray foam gets. I did spray foam some small areas.
Fiberglass batts are a decent way to DIY install insulation. Spray foam costs about four times the cost (installed) as fiberglass (installed) — and DIY is even cheaper with fiberglass, as the spray foam DIY kits are almost equal the installed cost according to the quotes I got.
The inspector and I spent about thirty minutes talking when he was there the first time (I think he wanted to make sure I knew what I was doing and wasn’t trying to hide anything), and he walked me through the next step. He said that I definitely needed a minimum of R-30 to replace the attic insulation (which was R-11 before) and R-13 on exterior walls since I had 2×4 framed studs. I’d need R-19 if I had 2×6 framing, but that’s uncommon in the south.
In the cold roof, which is 2×8, he said that the code calls for R-19 — but he suggested (in a very official voice) that I fit R-30 in there and sacrifice a little bit of R value from compressing it. The R-30 fit, but it was very difficult to get up into the flat roof and to staple in place.
It did make it a bit worse that some of the framing was not square, which made the individual bays farther than 23″ across — to the point where I had to put some dead wood in there on the sides of the rafters to get the 23″ wide can light arms to attach. That particular rafter was really bad. It was 13 degrees out.
Why not fix it? Can’t. Fixing it would mean removing the roof decking, or at least detaching that rafter from the roof. That would probably bust a hole in the roof. Since I didn’t feel like adding an entirely new roof to the tab…
You will notice that we stapled the insulation to the face of the studs and rafters instead of inside the studs and rafters. That’s because the kraft paper is a vapor barrier. Most builders and installers won’t do this. It’s time consuming and it makes installing the drywall a pain in the butt because you can’t see where the studs are. Contiguous vapor barriers are sort of a damnyankee northern thing that you have to do when you’ve got a lot more heating days than cooling days… however, they’re there for your protection, and in this case, could be the difference between this insulation getting moldy again and not.
So, last but not least, what I learned while hanging the insulation…
First, use a sharp utility knife that you can swap blades out of quickly but that doesn’t have a lot of other crap on it to get hung in the insulation.
Second, Arrow makes great staples (and their staples are standard), but they can’t make a staple gun worth a crap. BOTH of the electric Arrow-branded staple guns (ET501, ETFX50) that we bought when we start jammed continuously and failed under use. The ET501 actually stopped working due to overheating. What ended up working DECENTLY well was an Power Shot Pro gun that I found at Home Depot. Apparently these are made by Arrow, but aren’t listed on the website…
Third, you need to know what’s behind the insulation that you’re putting in. The R-30 insulation is a full 10 1/4 inches deep when it’s inflated — that’s close to the size of a 2×12. If there’s nothing behind it and you’re applying R-30 to a wall facing an attic, then you need to strap behind it. (I used spring steel hangers in some places and stapled straps in others depending on what I was doing and how much access to the backside I had.) If there’s wall behind there, or electrical, or worst of all water pipes, you need to separate the layers of insulation so that you’re insulating around those things.
Tomorrow, I’ll talk a bit about ventilation and how that works with the insulation in the cold roof… Or I’ll share some more pictures. Need some time to make diagrams, and I’m spending my day off today taping and floating…
