Saturday, February 20, 2016

What to do with a new disk?

Today two replacement SATA disks arrived from my favorite supplier. Reason enough to briefly summarize what I do when I get fresh disks: Maybe someone else can learn from the DOA mistakes of my youth when I trusted that a new disk would just work only to find that when I needed it, all it would do is "click click click" and that was that.

If you go through more disks than the average person, for example because you run a bunch of RAID arrays, I would first recommend that you get yourself a suitable docking station. Here's what I use:

UNITEK Dual Bay USB Docking Station
UNITEK Dual Bay USB Docking Station

I got mine from newegg.com of course. There are plenty of alternatives, little USB-to-SATA adapters or hotswap bays that mount in your machine's case, but none of those beat a decent docking station for convenience and versatility. (Note that I never use the "clone" feature of that thing, although I hear that it works fine.)

So unpack your new disks and do a quick physical inspection. If your supplier is decent at all, the packaging will be so good that it's extremely unlikely that you'll get something that's mechanically broken on the outside, so a glance is usually enough. Then slap them into your docking station and power it up. Open a terminal and do a quick check with dmesg:

[51407.603023] usb 1-1: new high-speed USB device number 4 using ehci-pci
[51407.718674] usb 1-1: New USB device found, idVendor=152d, idProduct=2551
[51407.718678] usb 1-1: New USB device strings: Mfr=1, Product=11, SerialNumber=3
[51407.718679] usb 1-1: Product: USB Mass Storage
[51407.718681] usb 1-1: Manufacturer: JMicron
[51407.718682] usb 1-1: SerialNumber: 00000000000000
[51407.719191] usb-storage 1-1:1.0: USB Mass Storage device detected
[51407.719353] scsi host6: usb-storage 1-1:1.0
[51408.142938] usbcore: registered new interface driver uas
[51409.223243] scsi 6:0:0:0: Direct-Access     HDD                       0000 PQ: 0 ANSI: 2 CCS
[51409.224849] scsi 6:0:0:1: Direct-Access     HDD                       0000 PQ: 0 ANSI: 2 CCS
[51409.225220] sd 6:0:0:0: Attached scsi generic sg6 type 0
[51409.225355] sd 6:0:0:1: Attached scsi generic sg7 type 0
[51409.229108] sd 6:0:0:0: [sdf] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
[51409.229476] sd 6:0:0:1: [sdg] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
[51409.230360] sd 6:0:0:0: [sdf] Write Protect is off
[51409.230365] sd 6:0:0:0: [sdf] Mode Sense: 28 00 00 00
[51409.231358] sd 6:0:0:1: [sdg] Write Protect is off
[51409.231363] sd 6:0:0:1: [sdg] Mode Sense: 28 00 00 00
[51409.232350] sd 6:0:0:0: [sdf] No Caching mode page found
[51409.232355] sd 6:0:0:0: [sdf] Assuming drive cache: write through
[51409.233613] sd 6:0:0:1: [sdg] No Caching mode page found
[51409.233616] sd 6:0:0:1: [sdg] Assuming drive cache: write through
[51409.286473] sd 6:0:0:0: [sdf] Attached SCSI disk
[51409.287473] sd 6:0:0:1: [sdg] Attached SCSI disk

Alright, looks like both disks are there having been recognized when the docking station powered up. Good! Now go ahead and check the details with smartctl:

# smartctl -i /dev/sdf -d sat
smartctl 6.4 2015-06-04 r4109 [x86_64-linux-4.1.12-gentoo] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Seagate Barracuda 7200.14 (AF)
Device Model:     ST1000DM003-1SB10C
Serial Number:    Z9A0GYZ0
LU WWN Device Id: 5 000c50 08774c950
Firmware Version: CC43
User Capacity:    1,000,204,886,016 bytes [1.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Form Factor:      3.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ATA8-ACS T13/1699-D revision 4
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is:    Sat Feb 20 17:34:31 2016 EST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
# smartctl -i /dev/sdg -d sat
smartctl 6.4 2015-06-04 r4109 [x86_64-linux-4.1.12-gentoo] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Western Digital Blue
Device Model:     WDC WD10EZEX-00WN4A0
Serial Number:    WD-WMC6Y0F4UPT5
LU WWN Device Id: 5 0014ee 0aec80cac
Firmware Version: 01.01A01
User Capacity:    1,000,204,886,016 bytes [1.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Form Factor:      3.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-3 T13/2161-D revision 3b
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is:    Sat Feb 20 17:34:57 2016 EST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

Good! Notice that I had to use the "-d sat" option to tell smartctl that there's really a SATA drive hiding behind all the USB stuff. (Took me a while to realize that I can do that, I used to think that SMART just doesn't work at all over USB.)

What you want to be looking for is the "SMART support is:" line. It's almost universally true today that SMART will be enabled by default, unlike back in 2002. But it's still good to check. In case it's not enabled, enable it. In case your disk doesn't support SMART at all, well, why did you order it? To enable SMART you'd say something like

# smartctl -s on /dev/sdf -d sat

but again, hopefully you won't have to. Alright, after all this prep work, we finally get to the point of all this: You want to run the basic SMART tests that all modern drives support. Note that especially the long test can take a really long time, so do this when you're sure you won't need the docking station for something else. First run the short tests:

# smartctl -t short /dev/sdf -d sat
# smartctl -t short /dev/sdg -d sat

Yes, you can easily run these in parallel because the disk is doing its own testing, your machine only told it to get going. For a 1 TB disk, the short test takes about a minute, but if you're impatient, you can check on the progress of the test as follows:

# smartctl -a /dev/sdf -d sat
...
=== START OF INFORMATION SECTION ===
Model Family:     Seagate Barracuda 7200.14 (AF)
...

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
...

Self-test execution status:      ( 246)    Self-test routine in progress... 60% of test remaining.
...

There's a lot more output than that, I just put "..." instead to keep things simple. (Actually you can get even more output with -x instead of -a if you really want.) After waiting for your minute, you can check on the outcome of the test with the same command. Toward the bottom of the output you'll hopefully find a line like the following:

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error

# 1  Short offline       Completed without error       00%         0         -

This indicates that the short test succeeded. Check the other disk as well, then get ready for the long test:

# smartctl -t long /dev/sdf -d sat
# smartctl -t long /dev/sdg -d sat

Same procedure as before, except that this time you can expect to wait for about two hours for a 1 TB disk. Hopefully the long test also works out just fine.

And there you have it, the minimum amount of testing I do on replacement disks these days before I put them on the shelf as I wait for a RAID array to fail. Of course if you have plans to encrypt the data on these disks you can do more "testing" by filling them up with random data now before you shelf them away.

Tuesday, February 2, 2016

Tired of Bernie Detractors

The recent uptick in so-called "liberal" commentators telling people who want to vote for Bernie Sanders why they shouldn't and why Hillary Clinton is the better candidate has me moderately pissed-off. It's true, you can never change anyone's mind on the Internet, but it's been so long since my last political post on this blog that I figured I should take a shot.

One of the first things you'll hear critics say is that Bernie stands for "wide-eyed idealists" which is a nice way of saying "idiot children who have no clue" in what passes for political discourse here in the US. Hillary of course stands for the "hard-eyed realists" which is to say "smart grown-ups who know the system" or whatever other "serious" thing. And heck, it may well be true that Bernie is an idealist and Hillary is not. What you should question, however, is if the valuation implied in most "think pieces" on this topic is correct: Is it actually true that a "realist" president is better for the country than an "idealist" president?

Think, for example, about how you haggle at a flea market or a garage sale. If the seller wants $10 for their lamp and you want to pay $5 for it, do you offer $9? Of course not! You offer $2 or, if you're feeling nice, maybe $3. You can't offer $1 because you know for sure that the seller will shrug their shoulders and wave you on. But offering $9 right away is actually an insane proposition, isn't it? Would you really "haggle" like that?

Yet this is what so-called "experts" bring up as a "plus" for Hillary: Since she's "realist enough" to offer $9, she might actually be able to get that for us. Big surprise there! If you propose to replace, say, really bad inequality with ever-so-slightly less bad inequality, you're going to find quite a few multi-billionaires who'll say "Alright, maybe I'll give up a few million here or there, at least I'll get to keep my head on my shoulders." and then you can give a State of the Union address that sells this pile of garbage as a huge success.

But remember what you wanted to pay: $5! Bernie might actually be "idealist enough" to offer $3 and then achieve $6 after some back and forth. Perfect? Probably not. But without someone actually haggling you'll just end up with $9. Or maybe $11: After all, in politics, unlike at a semi-sane garage sale, the "other side" has already raised their expectation to $13 between the time they told you $10 and the time they hear your $9 offer. That would make it even more important to have an "idealist" in office, wouldn't it?

Another thing you'll hear bandied about a lot is that Bernie will simply be blocked by Congress regarding every single proposal his administration might make. Once again this might be true, maybe Congress really would be more adversarial toward Bernie than toward Hillary. But again you should carefully think about the implications of this so-called "argument": If it's true that President Bernie can be blocked by Congress, isn't it also true that President Hillary can be blocked? Or President Donald?

Note that it's irrelevant whether President X will actually be blocked. That's simply one for the history books because you can only know it in retrospect. Indeed, anyone who is "predicting" it as a certainty for Bernie now is simply being dishonest. Politics is a dynamic process after all, and Bernie might be able to play his cards in such a way that Congress will eventually go along. (Maybe by starting to haggle at $3 instead of $9?)

Furthermore most of the "he'll be blocked" folks seem to completely forget that the President is not powerless in a fight with Congress: The veto allows a president to simply stop legislation coming out of Congress. That's not always easy, but it's clearly the case that a "mean Bernie" might be able to veto enough stuff to really make the legislative sweat. Don't forget that representatives and senators come from certain states, and if their states don't get something because of a presidential veto, the people responsible might find their incumbancy in grave danger. True, there might also be some "collateral damage" because "normal people" in those states might not get something they really need. But if the goal is to fix the whole country and not just a state here or a state there, well, that might be a sacrifice some of us are willing to make.

And of course Congress is not the only thing that can "block" a president. The "virtual senate" of bankers and traders around the world can achieve much the same simply by shifting capital around in such a way as to hurt a country until some policy (whether proposed by President or Congress) is "off the table" again. That's in fact in large part how "neoliberal austerity" works in places that are not officially beholden to Washington's machinery of World Bank and International Monetary Fund. (Hillary actually has experienced that first-hand back during Bill Clinton's first term when they tried to pass a semi-decent healthcare bill but were promptly shut down by Wall Street.)

As Iowa showed yesterday, Bernie has some real momentum. He also has better policies (for the 99% that is) regarding almost everything. Hillary will be "more of the same" just like her husband was (for the 1% that is). I cannot for the life of me imagine how the country could be "worse off" with Bernie than with any of the alternatives. But I can see plenty of things that could be better with Bernie. I am a card-carrying skeptic and cynic of course: It might turn out that Bernie is also "more of the same" in the end, who knows? What we know for sure is that with Donald or Hillary we're guaranteed that nothing gets better. With Bernie we at least have a shot. I am willing to take that chance, and I am tired of people who smear Bernie with "arguments" that are none.