how to test a 3T harddrive? - Page 1
Forum section: electronics / general

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 12:24:32 pm
content: nowadays harddrive have become *huge*Testing a 8GB or a 20GB harddrive makes sense with badblocks in terms of needed time and quality of tests, but ... with a 3T harddrive ... look:Code:Checking for bad blocks in read-write modeFrom block 0 to 2930266583Testing with pattern 0xaa: 30% doneafter 20 hours, I am still at the only the 30% of the first testing patter, and badblocks has 4 testing patters testing, so ...... isn't there a faster way?

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 12:31:10 pm
content: (I have a basket with 24 of those bloody huge harddrives, they are for the new rack of storage, but since machines here are all busy I can only use two embedded SBCs for testing harddrivesI think my boss asked me to do this job as kind of penalty retribution for having offended her preferredelixirfunctional programming language, which honestly - I do think - is pure garbage.I do largely prefer eRlang, but, never say it directly face to face to the boss.Lesson learned)

author: tunk
author_rank: Super Contributor
timestamp: August 23, 2021, 12:49:45 pm
content: You could try to add e.g. -b 65536 to the command.It could be that the SBC sata ports are really slow(~12MB/s). Do you have a spare desktop you could try?

author: SeanB
author_rank: Super Contributor
timestamp: August 23, 2021, 12:53:46 pm
content: Do you have a box with a number of internal SATA connectors, or USB3 connections, so that you can at least use 5 of the internal drive sockets to connect them, and the USB3 with a powered USB3 hub to connect some USB3 to SATA converters, which at least will allow you to test multiple at a time at close to full speed. There you will be mostly IO bound data transfer wise, but at least it will be faster.If not grab a USB2 to SATA adaptor, by as many as you can, and use GSMARTMON to at least do a full self test on the drives, which will at least see if it can read the entire drive as first pass, and there is no real data traveling over USB, other than polling. Will at least get the early failures out, and show you any that are already developing reallocated sectors, which on a new drive should be zero, as they were taken out at the factory.

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 01:49:25 pm
content: Quote from: tunk on August 23, 2021, 12:49:45 pmGood idea!Quote from: tunk on August 23, 2021, 12:49:45 pmProbably yes. Both SBC cards have a SATA/1 link, when I tried dd the speed was about 18Mbyte/sec on 100Mbyte copied from /dev/zero.Quote from: tunk on August 23, 2021, 12:49:45 pmUnfortunately not here. I have one at home, I think I will bring here tomorrow.

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 01:53:45 pm
content: Quote from: SeanB on August 23, 2021, 12:53:46 pmSBC ---> sATA/1 ---> diskAt home I have a Pentium4 thin computer with up to four sATA/2 free connectors.VIA chip. It should be faster.

author: PKTKS
author_rank: Super Contributor
timestamp: August 23, 2021, 02:40:34 pm
content: assumed missing quote added by moderator for clarity.QuoteJezzzuuus ....just tell this "her" to fuck off ...benn a looong time read/write tests are unfeasible.dd the whole thing in a blazing fast read-only test to void/null area.If that is OK - you probably are good to go using it.Later monitor as said w. smartmon tools to check SMART status.Just tell the odd creature to fuck off.. ignorance is boundedyou will spend the next month in such useless testingsPaul

author: tunk
author_rank: Super Contributor
timestamp: August 23, 2021, 02:45:15 pm
content: Or you could run it just one time: badblocks -svw -b 65536 -t 0xaa /dev/sdX

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 05:05:44 pm
content: Quote from: PKTKS on August 23, 2021, 02:40:34 pmI am afraid about the next punishment for this colored sentence ... she is *somehow* a nice woman, but sometimes with a very bad temper and *quite touchy* about architectures (like EPIC -> Itanium), tools and languages that she likes.At least now she knows what I think about Elixir and she won't assign me tasks with that(I hope)Quote from: PKTKS on August 23, 2021, 02:40:34 pmI am not sure about this. Last year I found a couple of disks that passed dd if=/dev/sdb of=/dev/null but when I tried to write something they simply lost dataedit:I found a couple of disks(1) that periodically disconnect themselves from the pATA link. I don't know how to explain, but I saw the kernel stalled up into an infinite loop trying to "reset" the unit; I double checked cables and tried with different pATA controllers, all the same, and the problem was only detected by Badblocks while apparently things looked perfectly ok.I mean, I was able to compile Gcc with those two disks, but probably Gcc was not stressing so much the units like Badblocks does. But, I don't know. It's just my speculation.(1) Quantum 27GB Fireball Plus F/W A350799.

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 05:06:56 pm
content: Quote from: tunk on August 23, 2021, 02:45:15 pmOK. If this is enough, I will use it! Thanks

author: andy3055
author_rank: Super Contributor
timestamp: August 23, 2021, 05:14:08 pm
content: Take her out to a good dinner and claim the expenseslater!

author: DiTBho
author_rank: Super Contributor
timestamp: August 23, 2021, 05:17:19 pm
content: Quote from: andy3055 on August 23, 2021, 05:14:08 pmahah, brilliant idea

author: isometrik
author_rank: Regular Contributor
timestamp: August 23, 2021, 06:04:17 pm
content: I have been testing internal (so SATA connection) 8TB HDDs with the following command and the overall test took less time than your first pass. :badblocks -b 4096 -swvt random /dev/sdaThis approach is not as thorough as yours, as it only performs one write cycle followed by one read cycle, but the data written/compared is random... so it's good enough for me to assess the health of the HHDs.

author: David Hess
author_rank: Super Contributor
timestamp: August 23, 2021, 07:13:00 pm
content: There are test programs like HDAT2 and MHDD32 but as you observed, this method ties an entire machine up on one drive unless you use them to order each hard drive to run its own surface scan function through SMART.Some HBAs (host bus adapters) have diagnostic functions which allow every connected hard drive to be tested independently. For example the old 12xx series of Areca RAID controllers can either use each hard drive's SMART functionality to perform a surface scan, or can do its own read or write surface scan while monitoring for media errors. The write operation is especially useful since it will force reallocation if a bad block is detected.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 23, 2021, 07:39:27 pm
content: I prefer to rely on the SMART long self-test, and compare the raw attributes before and after.Sure, badblocks is a brute-force method to check each block, and perhaps warranted when considering reusing old drives (I don't do, haven't done that, my self).When I maintained a couple of HPC clusters a bit over a decade ago, SMART attributes (reallocated sector count and so on) sometimes gave an indication a couple of dozen hours before a spinning rust drive started failing completely, but about as often the drives just failed without any kind of reliable predictable pattern at all.The question is whether one considers swapping a possibly failing drive for a new one worth it, or whether waiting until a drive actually fails before swapping it is more appropriate. In HPC clusters, it depends a lot on the type of simulations run, and the cost of failing a simulation due to hardware failure.(Not many HPC clusters use checkpoint-restart for migrating running simulators, and instead just handle nodes individually by hand.)If the drive is to be wiped, doing a full SMART self test, then overwriting the entire drive with zeros, and redoing a full SMART test again, comparing the raw attributes can tell whether the drive is "stable" or may have issues. My own diagnostic criteria (of what kind of attribute changes I consider acceptable) causes me to reject drives that have a good chance of working fine after all, but that's OK, because I'm after my own peace of mind only.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2021, 07:41:38 pm
content: I would take the 10,000ft view. I would drop three of the drives, test them, wait for the failures and then explain as an engineer it’s not worth the time to test the restThat also covers the “fuck you for making me do this shit” scenario.

author: David Hess
author_rank: Super Contributor
timestamp: August 23, 2021, 08:52:59 pm
content: Quote from: Nominal Animal on August 23, 2021, 07:39:27 pmThe SMART long test is very useful however it will not force reallocation of bad blocks so a write test like I described is more thorough.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 24, 2021, 12:06:27 am
content: Quote from: David Hess on August 23, 2021, 08:52:59 pmAbsolutely true.On machines with SMARTy spinning rust, the smartd service will basically do the same in the background, with very low I/O priority. I use it on machines in heavy enough use so that disks stay spinning, as otherwise smartd can cause extra disk spin-ups (depending on disks and smartd config).Writing zeros (or any data, without reading the block first) will not do any verification on the platter state at all. Writing the spinny disk full of zeroes is just a quick-ish way to ensure a "clean" state. I also do an offline test before the full self-test, to verify the attributes shown are properly up to date.In Linux –– both desktop (x86 and x86-64) and SBCs (various ARMs) –– I've found cheap USB3 SATA adapters based on JMicron JMS578 work fine, with >200Mbytes/sec transfer rates (continous). These are dirt cheap, but have native Linux support, and perform well enough with spinning disks. You'll likely need to supply both 5V and 12V separately to the SATA power connector, since spinny disks do need a few watts of power to run; make sure that the USB ground and SATA power ground are connected and in the same potential (no ground loops). I recommend truly isolated supplies (no protective earth, no capacitors from low-voltage side to protective earth or primary side) for this. Proper docking stations are nicer, but cost several times the cheap adapter. For dd, I tend to use bs=2097152 or bs=4194304 (2 or 4 MiB blocks); for badblocks, I'd try -b 65536 -c 64 (4 MiB at a time if possible).I do have one HDD docking station, an old USB 2 Akasa DuoDock. Works fine, but is slow. Mine sits on top of two-inch thick closed cell foam, which removes all resonance noise; the foam is glued to the bottom of the station. I recommend that for anyone working with spinny disks and external docking stations; the resonance when sitting on hard surfaces is really irritating, especially seek noise.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2021, 02:54:30 am
content: Quote from: Nominal Animal on August 24, 2021, 12:06:27 amI sometimes use an anti-static foam pad. The vibration is also annoying when it allows the drives to "walk" off of the desk and fall on the floor in the middle of the night. Last year I bought a couple ofthese rackswhich when combined with any ATX power supply will power and cool 5 drives each, and they are stackable.

author: magic
author_rank: Super Contributor
timestamp: August 24, 2021, 08:26:45 am
content: The bottleneck is obviously the shitty-ass machine which can barely do 18MB/s from /dev/zeroEven old SATA1 is about adequate for most spinning rust, with speeds in excess of 100MB/s.SMART self-test is nice but doesn't catch disks that fail to write new data correctly. "Reallocating bad sectors" isnotwhat you want, you really prefer to find them and know that the disk may be getting unreliable. So you should start with reading the whole disk before writing anything. This can be done with SMART. But you then want to write too, and here SMART won't help.

author: DiTBho
author_rank: Super Contributor
timestamp: August 24, 2021, 10:46:34 am
content: Quote from: magic on August 24, 2021, 08:26:45 amDon't be so surprisedPCI-machines cannot give you more than 20Mbyte/sec with SATA HBA on a PCI32bit@33Mhz, it's easy to say "shitty-ass", but it's hard to debug the kernel 5 to squeeze out more performance.For weird reasons here I only have available only a SBC and an old RISC workstation. Both are slow with sATA, both are based on PCI32bit@33Mhz. All the *big* and *modern* PCIe machines here are busy and I cannot use them, neither I can use PCs in our office, today I bring my personal PC from home, it's a modern PCIe 1x minicomputer, but I can somehow attach an adapter and use a MEGAraid card.The MEGAraid is PCIe16, it comes with a smart controller, and two SAS lanes, which means 8 sATA links.Maybe I can test 8 harddrives in parallel(just, I took it from my boss's office and I haven't yet told her about this plan)

author: magic
author_rank: Super Contributor
timestamp: August 24, 2021, 12:10:55 pm
content: Maybe your PCI machines. I'm under impression that I tested a gigabit NIC on a Pentium II box at one time in the past and it delivered close to the rated throughput. 32b × 33MHz - do the math

author: DiTBho
author_rank: Super Contributor
timestamp: August 24, 2021, 01:12:59 pm
content: Quote from: magic on August 24, 2021, 12:10:55 pmThe math is easy, in theory:Code:bandwidth = frequency * bitwidthTherefore:bandwidth = 33.33 MHz * 32 bits = 1067 Mbit/s = 133.32 MB/sPCI 32-bit, 33 MHz: 133.33 MB/sPCI 32-bit, 66 MHz: 266 MB/sPCI 64-bit, 33 MHz: 266 MB/sPCI 64-bit, 66 MHz: 533 MB/showever, I told you, it's easy to "math it", but ... can you hack the kernel to squeeze out performance?expected: PCI 32-bit, 33 MHz: 133.33 MB/smeasured: PCI 32-bit, 33 MHz: 18 MB/s (sATA)measured: PCI 32-bit, 33 MHz: 20 MB/s (SCSI-NA8SE)measured: PCI 32-bit, 33 MHz: 60 MB/s (SCSI-UW16)measured: PCI 32-bit, 33 MHz: 50 MB/s (1000BaseSX)I installed the MEGAraid card in the PCIe1x slot and it is really impressive: it squeezes out 100Mbyte / sec from the disk even if it is underpowered due to the 1x lane connectionBut I need a 16X lane to fully use it with 8 sATA connections. Meanwhile, while I'm *somehow* testing two hard drives in parallel on two on two *makeshift* computers, I fortunately found an abandoned assembled PC in a cornet of the lab buried under a stack of old stuff. It doesn't look good because it's really an ugly case with scratches, but it works and it's not too bad since it provides one PCIe 16x slot, so I'm going to get it to test the rest of the drives in the trash.Luky found, and with the MEGAraid I think I'll wrap up this stuff soon

author: daqq
author_rank: Super Contributor
timestamp: August 24, 2021, 01:25:57 pm
content: QuoteSo what you are saying is that you have billable extra work approved by your boss that effectively lets you do whatever you want until the task finishes itself? Are you sure that you don't want to double check them just to be sure?https://xkcd.com/303/edit: More seriously, unless you can get extra machines to run several in parallel or get some USB 3.0-SATA adapters to run the test on any existing machines in the office then I don't think you can speed it up much if you want to be thorough.

author: DiTBho
author_rank: Super Contributor
timestamp: August 24, 2021, 01:47:24 pm
content: Quote from: daqq on August 24, 2021, 01:25:57 pmYup, I was thinking something similar, I mean ... Amazon has some, and can deliver in 1-2 days.Meanwhile I have planning theKubernetescluster; it's where these disks will be installed on Monday.And that's the deadline for this disk-testing activity.

author: bd139
author_rank: Super Contributor
timestamp: August 24, 2021, 01:59:55 pm
content: LOL enjoy kubernetes on horrible disks like that.We have about 900TiB of enterprise SSD and EBS online and that’s still giving us IO issues. There ain’t enough time in the world for the disk to go round to the head these days.

author: DiTBho
author_rank: Super Contributor
timestamp: August 24, 2021, 03:30:40 pm
content: Quote from: bd139 on August 24, 2021, 01:59:55 pmWhy horrible? They are WDC WD30EFRX-68EUZN0, 3TB red-line sATA hard-drives.The only problem was the slow controllers I had on hands before finding the MEGAraid card, and that all the nodes of the clusters will be delivered next week, otherwise I would have directly installed the disks into nodes and used them to test all the disks.

author: bd139
author_rank: Super Contributor
timestamp: August 24, 2021, 04:02:16 pm
content: Kubernetes clusters tend to have massively fragmented IO. 5400rpm + rotating disk = IO waits = cluster of pain. Obviously depends on workload profile but that’s going to suck. It’s sucks on 15K DAS SAS on HP DL580G10’s.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2021, 08:29:49 pm
content: Quote from: DiTBho on August 24, 2021, 10:46:34 amI have regularly gotten 100+ MByte/sec on my ancient (Pentium III and Pentium4) PCI machines and SATA 1. Often the limitation is how the hard drive is being accessed.QuoteMy suggestion about using a better HBA is that some cards, like the old Areca ones I mentioned, have the read and write diagnostic functions built in, so all of the read and write traffic is over the SATA buses between the hard drives and the card and not over the PCI bus.

author: DiTBho
author_rank: Super Contributor
timestamp: August 24, 2021, 09:38:00 pm
content: Quote from: David Hess on August 24, 2021, 08:29:49 pmI tried with different cards (sATA, SCSI, optical Ethernet) and modern hard-drives (sATA, UW160 SCSI 15Krpm), but not on x86 machines.Linux on machines like Apple PowerMac G4 are slow with the PCI. Never tried with MacOSX, but it's pointless, that PowerMac is there for an industrial scanner, that's its purpose, and I won't touch it anymore, even because it's slow.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2021, 09:50:19 pm
content: Quote from: DiTBho on August 24, 2021, 09:38:00 pmDuring the Pentium4 era, I had some nVidia nForce2 boards for less critical applications and they could only pump about 90 MBytes/sec over their PCI bus. If there was a configuration setting to fix this, then I never found it. Comparable Intel boards managed at least 120 MBytes/sec.As you have observed, PCI bus performance can be limited to a considerably lower level.

author: BradC
author_rank: Super Contributor
timestamp: August 25, 2021, 12:44:58 am
content: As previously mentioned, a full disk read can be done with a SMART long test. This will abort on the first read error.A full disk write can be done with a secure erase :https://grok.lsu.edu/article.aspx?articleid=16716With an WD drives in an array, we disable the spin-down and head-park. When we "burn-in" new drives we do it by building them into the array they are destined for (in a staging machine) and beating the snot out of them for a week with random IO workloads. This is time consuming and resource intensive and has *never* weeded out an early life failure. We've still had the odd disk die from a couple of months to within the warranty period.Next time I build an array I'm going to do a SMART long on the drives, build the array, let them idle for a week and put them into service.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 25, 2021, 07:25:34 am
content: Quote from: DiTBho on August 23, 2021, 12:31:10 pmJust toss them in the rack and build up the array. If one fails during the build, just replace it and rebuild. It's why your have more than one.Testing each drive before putting them in an array does not add any value.

author: DiTBho
author_rank: Super Contributor
timestamp: August 25, 2021, 09:23:23 am
content: Quote from: Jeroen3 on August 25, 2021, 07:25:34 amI don't have a rackQuote from: Jeroen3 on August 25, 2021, 07:25:34 amI don't have to build an arrayQuote from: Jeroen3 on August 25, 2021, 07:25:34 amMy colleagues have to build a cluster, two disks per nodes in software RAID1.But the hardware to build the cluster hasn't yet been delivered.

author: DiTBho
author_rank: Super Contributor
timestamp: August 25, 2021, 09:24:45 am
content: Quote from: BradC on August 25, 2021, 12:44:58 amThat's very interesting! Never heard about this. Thank you!Does it also work for SCSI? I have a dozen of disks at home, but this is for hobby purpose.

author: magic
author_rank: Super Contributor
timestamp: August 25, 2021, 09:28:23 am
content: It doesn't work for almost anything.Well, SSDs often support it because they use AES as scrambling algorithm and therefore SE is as easy to them as throwing away the key and generating a new one (and that's how they do it).

author: DiTBho
author_rank: Super Contributor
timestamp: August 25, 2021, 11:07:57 am
content: This morning I quickly found two defectives harddrivesThe controller said *there is no physical device connected to the sATA channel xx* ... but obviously there were two pieces of physical metal with a connector on each, but it was just ... dead rusty stuff.I double checked the MOLEX connectors, tried again, same result: the motor did a weird sound, like like a wounded animal, and then it fell silent by turning off all the leds and signals.They are dead, I am sure they are dead disks, the MEGAraid controller never goes wrong. I am going to open a return ticket for a full replacement, I hope Amazon will be fast with that.Let's go testing the others, with the current speed I can test up to 8-9 disks per day (24h)

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 25, 2021, 10:41:12 pm
content: Yup, that's what the tests are good for: detecting if the drive is dead on arrival, not much else. Even the early deaths tend to be just as unpredictable as late deaths, so having a drive pass any kind of test is not proof of long life expectance, only that right now, the drive is okay.But, when you're building machines, especially clusters, weeding those out makes the process work better. I mean, whenever a node does not come up normally, the reason could be just about anything, from badly seated memory, to a faulty motherboard, CPU, drive, or whatever. Nasty to debug. If you know the drives work, then at least you can exclude one possible cause. Me, I like to take the node apart, clean everything (and if I have the time and the chassis is empty, deburr the damn edges of the stamped metal parts, because my fingertips are worth to me more than the two minutes it takes to do; plus if you do vacuum the chassis, you'll surprisingly often suck up small detached metal burrs and forgotten screws that can cause an occasional short), and put back together again. I didn't gather any statistics on how often that made a difference, but when you set up a few dozen compute nodes, you canexpectto have bad parts in the batch for sure, no matter what the vendor.It's just what it is.

author: BradC
author_rank: Super Contributor
timestamp: August 25, 2021, 11:55:37 pm
content: Quote from: Nominal Animal on August 25, 2021, 10:41:12 pmMost drives have a SMART conveyance test which is pretty much just designed to check the mechanics weren't damaged in transit. A couple of minutes vs many hours for a long test.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 26, 2021, 12:42:08 am
content: Sure, but when a drive comes off its packaging, and its SMART log is completely empty, to me it means that the drive hasn't ever been completely self-tested, aside from whatever production tests the manufacturer does while putting the drive together.Still, I do admit that doing a full (long) SMART self-test for a drive can be considered overkill. In most cases, it will go just fine, reports no problems, and nothing suspicious happens with the SMART attributes. To me, on my personal workstation I use all the time, that is worth it for the peace of mind. Like I said earlier, when I build my own machines, I even deburr the stamped metal edges. (It's not being anal or pedantic or perfectionist; it's the small cuts in my fingerpads that I hate, and consider the time and effort worth the results.) I also add sound-absorbing foam and baffles and such, but I'm not sure if that is because I need them, or because I like building that sort of machines. (No, I don't add LEDs; I like my machines silent and unobtrusive.)For cluster nodes, I usually do SMART tests in parallel on the nodes, as one step in the initial testing process; memtest is another. Those that do not come up immediately, or show issues during initial testing, I do the second-degree teardown-rebuild way, using a know good machine to test the drives. It takes time in the latency sense, but I believe it saves me time, since I can isolate the problem source faster. On a new drive, I'm not sure ifbadblocksis worth the time. On an used one, I'd say it is; as well as drives from manufacturers like Seagate with some series of drives having lots of DOA units.A small fraction of hardware is always b0rked on arrival, that's a given. I personally am willing to spend the time to weed the immediately observed ones out as early as possible, even if it takes an extra 24 hours or so (assuming I can do other stuff for that duration, obviously; I'm not going to babysit such tests). Then again, I definitely weigh time spent differently to say a commercial entity which uses the drives for bulk data storage. Your mileage and weights/emphasis may well differ, no argument there on my part!That is, I do not know what level of testing is appropriate for anyone else, because it really depends. I'm only hoping my wide description of what I do and why gives a sample point others can use when deciding what they think is appropriate for their use cases.

author: DiTBho
author_rank: Super Contributor
timestamp: August 26, 2021, 09:17:53 am
content: Well, for another project, I also suspect a serious bug with kernel 5.12. I cannot say anything at the moment: it can be a software problem, or an hardware problem, including defective harddrives.

author: DiTBho
author_rank: Super Contributor
timestamp: August 26, 2021, 09:46:45 am
content: Two years ago I ordered a set of qty=40 ram-sticks and was shocked as more than 50% of them were defective.Code:_________________|| G B G B G G B G || B G B G G B B || B G B G B G B G || B G G B B G B || G G B G B G B || B B G G B G B G || G G G B B G B ||_________________|G=good unit, fully workingB=bad unit, damagedp(B) >> p(G) ---> QA=WTF?!?How can it be? And if you get them in a black box sent from Amazon from a respectable seller (5 stars with good feedbacks and reviews) and you don't know the distribution, so what to think when you pull out random RAM, try it on your experimental SBC, and things start going crazy with several completely crazy malfunctions?Is it the ram? or is it a bug in your firmware? or is it a bug in your kernel setup?Is it external fault or internal fault? Both are possible, but which one is the one?Both can even happenSo, you have to be sure that the ram is not faulty, but when you see that more than 50% of the units are "measured" as faulty, it's so weird to see that you start questioning everything: the Amazon's QA, as well as your own testing methods.Code:_________________|| G G G G G G G G || G G G G G G G || G G G G G G G G || G G G G G G G || G G G G G G G || G G G G G G G G || G G G G G G G ||_________________|I remember I sent the ram-box back, got a refund and bought it again from another seller, with a completely different result: zero defective parts found

author: bd139
author_rank: Super Contributor
timestamp: August 26, 2021, 10:10:23 am
content: I think you may have just found a defective seller there.Best to buy from respectable retailer ie crucial.

author: cdev
author_rank: Super Contributor
timestamp: August 26, 2021, 01:47:34 pm
content: Do you have a URL where I can read about these racks?Are they aimed at cryptocurrency "miners" ?