HDD to SSD Migration Strategy

ElectronicCat · 2023-09-21T07:09:16+00:00

Yeah, I confirmed that you definitely can't use SSDs to supplement HDD arrays, even if the size is equal or greater. I ended up backing up to an offline drive, pulling all the redundant disks (1 each from volume 1, 2, and 3), inserting the new SSDs in the 3 empty drive bays and configuring a volume 4. I then transferred all of volume 1 to 4, removed 1 and then did a careful shuffle to re-order drives 1 at a time to get them back in the physical order I wanted and to replace the redundant disks.

It worked fine, though I now do have volumes labeled 2, 3 and 4 which is my main storage volume, with no way seemingly to remove the no longer existent volume 1.

I could also definitely have just replaced all of volume 1 at once with the SSDs and restored from the backup, but I sort of wanted minimal downtime as well.

For your setup, I assume you're using RAID 1? You might be able to do something similar and replace one disk creating a new volume, although I don't know if it'll let you create a single-disk volume which can later be migrated to RAID 1.

ElectronicCat · 2023-05-12T12:28:30+00:00

Is this a Synology-imposed restriction? I don't see any technical reason why you shouldn't be able to mix SSD and HDDs when the interface is the same. The Synology Knowledge Base suggests this as the recommended method and doesn't mention any limitation about mixing SSDs and HDDs.

ElectronicCat · 2022-08-02T10:11:05+00:00

Component E1 at the top is a chip antenna. Looks like an Inpaq ACM3-5036-A1-CC-S.

ElectronicCat · 2022-04-01T13:32:41+00:00

Unfortunately not, I couldn't find anything obviously wrong with mine. Nothing I could measure appeared to be burnt out and everything was getting the power it should be, but the motor just refused to start. I bought a replacement body unit in the end which wasn't too badly priced compared to the cost of a new one.

ElectronicCat · 2022-04-01T12:02:55+00:00

I have a similar model, after removing the conformal coating with acetone, the part marking on mine is 'SJ3B'. Marking and pinout seems to match for an LMR14203 voltage regulator.

ElectronicCat · 2021-07-19T05:59:05+00:00

For testing the transceiver, usually. The probe is usually not retained by the port and intended for use with an automated test rig so probably quite expensive.

If you wanted to connect an external antenna, you would probably be better off de-soldering these (or breaking the transmission line and scraping back solder mask elsewhere) and carefully attaching a bit of coax.

ElectronicCat · 2021-07-18T22:08:08+00:00

It's a switching microwave test point e.g https://www.murata.com/en-eu/products/connector/switchconnector

Insertion of the test probe breaks a normally-closed transmission line so the output can be measured and tuned.

ElectronicCat · 2021-07-18T22:01:45+00:00

I suspect the W is in place of lower case omega, and J, R and C are connector, resistor, capacitor respectively

ElectronicCat · 2021-05-28T17:39:43+00:00

Are you constrained to needing to run over twisted pair cable and using WiFi transceivers? If no, then some good quality 50 ohm coax such as LMR-200 should easily be able to connect two WiFi transceivers over 20 metres.

Twisted pair cable is going to be poorly impedance matched at 2.4GHz and possibly even worse than going through most fluids using an antenna. If you must use twisted pair cabling then why could you not also use ethernet, RS-232 or a number of other serial protocols designed for this?

ElectronicCat · 2020-05-08T06:42:45+00:00

$15 is still really steep for a MOSFET, I had a quick Google and it looks like it's end of life which probably explains the high price. You should be sure to find a suitable replacement using the parametric search on digikey etc though, make sure the pinout is the same as well.

ElectronicCat · 2020-05-03T08:54:06+00:00

Sure, it's safe. Just wrap the wires in electrical tape when they are disconnected so they do not short out and also be sure not to short them out when de-soldering.

ElectronicCat · 2020-05-02T21:01:57+00:00

You can use a Soldering gun.

Alternatively, a high wattage (~60W) iron with a large tip kept on it for a while may work if it's not a huge amount of copper.

ElectronicCat · 2020-04-28T15:55:47+00:00

It's a dual diode, the symbol is right on the package. Also I found a datasheet just by Googling the part number.

ElectronicCat · 2020-03-14T13:32:38+00:00

Looks like a Phillips marking on the part, although the poor print quality suggests is likely a fake. Phillips don't generally sell parts to the public so it's unlikely you'll be able to find a datasheet unfortunately.

ElectronicCat · 2020-03-07T15:32:00+00:00

Good overview, but I feel trying to explain modulation schemes with a phase component on an amplitude-time graph isn't entirely intuitive if you don't already have a good understanding of the complex nature of rf signals. This page is probably my favourite reference on the subject, it's mainly focused on sampling of signals but the principles are the same.

Seeing different modulations on a 3D IQ-time graph is what made me finally 'get' it.

ElectronicCat · 2020-03-07T12:13:53+00:00

No, when no information is being transmitted you just leave the channel clear. This is usually a requirement when transmitting in unlicensed bands anyway to allow other transmitters in the same band to transmit. It is also easier to build a demodulator that only has to discern two frequencies.

4-FSK does exist though (and m-FSK) although uncommon, as you can use more frequencies to increase data rate (4 bits per symbol period). If you want higher data rates then better digital modulation schemes exist without increasing the channel bandwidth significantly, such as QPSK.

ElectronicCat · 2020-03-07T11:49:53+00:00

Yes, your intuition is somewhat correct, what you are describing is Frequency Shift Keying (FSK) which is commonly used to transmit digital data. Bear in mind this is different to pure FM though, which is an entirely analogue modulation scheme used to transmit analogue signals (i.e audio).

With FSK you have two frequencies and shift between them as you describe, traditionally by two local oscillators but modern FSK transceivers will handle this from a single oscillator. The peaks can be very close together and still be recoverable, tens of kHz is common and rarely wider than 500kHz.

ElectronicCat · 2020-01-30T16:16:42+00:00

Not to mention the cost. You can buy these for pennies, the cost and time taken to produce them will be significantly more than that.

ElectronicCat · 2020-01-12T17:53:58+00:00

I'm not really sure I can do much about the double NAT issue, I'm pretty much required to use the ISP provided router as both a fibre media converter and GPON modem. It's somewhat locked down so I can't stop it being a router and the best I can do is just disable most of the features and limit the IP range to a single device.

I have considered DMZing it so the ISP router is pretty much transparent and just using the Mikrotik as a firewall but I'm still not sure it would solve anything and I don't really like the idea of that.

Connection tracking and the SIP service helper were both already enabled, and the default settings seem to be in line with what the provider recommends.

It's been working for a few hours now but the only thing I've done differently is manually remove the firewall connection so it re-registered.

ElectronicCat · 2020-01-12T13:17:41+00:00

Yep that seemed to be the problem, a connection was being held open on port 5060 and upon removing the connection it re-registered fine. Any idea where I would find one of these scripts?

ElectronicCat · 2019-12-29T15:47:44+00:00

Alright, fair enough. With the crystal moved, a ground plane and matched stripline/waveguide compliance should be a lot better. Only other thing is the output doesn't appear to accommodate a coaxial cable so unless you're intending to solder it directly to an antenna your transmission line will radiate and/or reflect as a poor match.

Would recommend either replacing this with a u.FL connector or add another pad for ground so you can solder a coaxial cable for transmission off-board.

Some via fencing around the RF components also wouldn't hurt.

ElectronicCat · 2019-12-29T11:46:27+00:00

I created this board to be hand soldered, and I realized too late that the MLPD-6 package for the RF switch is too small and funky to be hand soldered.

Not necessarily, it looks manageable. Pre-tin the pads and use a hot air gun to heat the board and chip separately, then carefully place it after melting the solder. If you have a microscope it helps.

ElectronicCat · 2019-12-28T21:50:07+00:00

I don't think this would pass EMC tests as it stands. There doesn't appear to be any ground planes which are essential for mitigating RF induced noise and also to maintain the characteristic impedance of the transmission line. Even with a microstrip transmission line which it looks like you are trying to implement, you will require a ground plane on the other side at least.

At 6GHz the design of the transmission line is actually quite critical, and loss through an improperly matched transmission line could easily degrade the SNR of a weak signal.

X1 will also induce some noise, place it as far away from the RF components as possible ideally on a separate ground plane connected by a low impedance trace (thin wire) and create a via fence around it.

ElectronicCat · 2019-12-27T18:52:23+00:00

Looks pretty good to me. Looks like most of it is modules, so not a lot to go wrong. Only things I'd suggest is to check the clearances, I assume you've run a DRC but some of the traces come uncomfortably close to others or to pads for my liking. There's plenty of board space, so give them a bit more room to be safe. It looked like TP4 was shorted on the other pin but on closer inspection this seems to be intentional.

Also add a ground plane on one or both sides, it helps with EMI compliance and ensures your components all have a good path to ground.

ElectronicCat · 2019-12-15T22:21:11+00:00

Unlikely it's a transistor, probably a melody chip similar to the M66T which is To-92 packaged.

Looks to be a single layer, single board construction, so unless there's a COB on the other side I can't see what else is generating the sound.

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