Error message but recording OK

[Anonymous]

The forum recommendation is the Sandisk extreme usb3 stick. I have the 64gb version

[jhb1982]

Andreas – thanks. Re. cluster interleaving, that makes perfect sense. Wrt errors – well, in my case my mixer is usually setup next to my drums! The same thoughts crossed my mind, but I have observed errors being reported when not playing. A read/write test of every sector does not throw any issues, so I don’t think there’s been sustained mechanical damage (i.e. it doesn’t explain what’s happening under stable conditions).

The suggestion to switch to a non-mechanical drive makes sense. I guess the only issue is memory wear, but I gather most drives/sticks achieve upwards of a million P/E cycles these days?

Thanks for the tip Bob – I wasn’t sure about using a stick as most seem to lack the raw throughput, but reading around the SanDisk does appear to do the job. Worth a punt for 35 quid! Is this the exact model? (Getting paranoid now!)

[Anonymous]

Looks like it. I also have a short USB extension cable with a right angle at the desk end, so the whole thing is low profile at the desk.

[Andreas]

Maybe checking the reallocation sector count from the drive’s S.M.A.R.T. info would help. Regular read-write tests don’t tell much, since the drive internally performs CRC checks and reallocates logical sectors (as accessed from the host) to spare physical sectors in case of excess errors.
Maybe your drive received some damage during transport and observed write errors may indicate new sector reallocations.
…or that particular 5400 drive is simply too slow regarding seek times…

[DHOYT]

Hi Andreas, in your post above, you said:

“And just to repeat some hints for recording multitrack on HDD:
– always start recording on a freshly formatted device (no fragmentation at all)

UNDERSTOOD TO MEAN FORMATTED BY THE QU DESK.

– do not copy additional files from a PC to that drive (recording need to seek around that data)
DO YOU MEAN LIKE WAV FILES FOR 2 TK PLAYBACK FOR PRESHOW ETC. OR SHOW, OR PATCH INFORMATION?

– do not erase files/sessions (this also requires additional seeking)

I TAKE THIS TO MEAN THAT AFTER TRANSFERRING MULTI TRACK SESSIONS TO THE COMPUTER THAT ONE CAN NOT JUST ERASE THE SESSION. RATHER, THE DRIVE NEEDS TO BE REFORMATTED BEFORE THE NEXT SESSION. IS THAT CORRECT?

– do not defragment a multitrack recording (interleaved tracks will get sorted, resulting in additional seek times)

I’m using WD Passport 500 gig and have yet to get consistent multitrack recordings from my QU24 desk. One 2hr show will record just fine and the next won’t. I think what your saying is that the drive should be reformatted before every session and that if I wanted to use another feature like 2tk playback, or virtual sound check, that it should be on a separate drive. is that correct?

Thanks,
David

[Anonymous]

Ideally the disk should be completely empty/defragmented before recording a show.

That lets the QU write sequentially – hopefully to a region without any reallocated sectors (which need the head to seek across to the “spare” area, and then back to carry on).

To seek the drive needs to move the write head sideways, then wait for the disc to do (on average) a half rotation, which even at 5k rpm is a long time in computer time…

[Andreas]

[sorry for this lengthy post…]

Lets dive down into the filesystem to clarify your questions: The used FAT32 filesystem is rather simple (i.e. more deterministic than, for example, NTFS but way less reliable…). It basically consists of equal sized buckets (called Clusters) which finally contain your data. A freshly formatted drive obviously only contains many many empty buckets in a row, each one has a unique number.
If a file is written to the drive, the first empty bucket is filled with your data. If the file does not fit into a single bucket, the next empty one is picked etc.
To retrieve your data later (reading the file), the system keeps track of the first bucket number in the file directory (along with modification time etc.). If the file does not fit into a single bucket, the File Allocation Table (=FAT) is queried. This is a simple table with one entry per existing bucket containing the number of the successor bucket, if any. Some sort of linked list.

Ok, back to the questions. If files are copied to a freshly formatted drive, you can be somewhat certain that the buckets used are strictly in order. If a bunch of stereo WAVs is copied to that drive (i.e. Preshow files), these will occupy a more or less large section of your drive. As long a the operating system writing these files does not try to be clever (i.e. preserve some space between files in case they may receive additional data in the future), the drive is still fine for multitrack recording.

If you later decide to delete some of these files several buckets of that section get empty again and will be re-used for the next file written. If that file is larger, it will be “fragmented”, meaning the beginning is written into the freshly emptied buckets and the remainder somewhere else. This shouldn’t be an issue for preshow playback but may lead to errors during multitrack recording (seeking, FAT updates).

So major golden rule: Only write files to such a drive, do not delete individual files or folders!

Recording multiple multitrack sessions in a row is not a problem.

But, yes, if you’re done with recording(s) after a show and transferred the files to your PC, the drive should be formatted to get back the space. Of course you also loose your preshow files in this step, so it is up to you to decide to either use a separate disk or a different source for preshow music.

Arming and finalizing a multitrack recording takes a lengthy second. Not sure if you can hold the band offstage long enough for the QuDrive gets ready after stopping the music…

[DHOYT]

Thank you both for your prompt replies.

1) The previous show to this last one, I had just formatted the drive and I had no problems with recording a 2 hr multitrack show.
2) After dumping the files into my home computer, I erased them from the recording drive.
3) I did not re-format prior to the most recent show and I also added some wave files for preshow playback.
4) During set up, I noticed that the QU 24 was having a hard time recognizing the drive. One time I re-booted (because I don’t know if there is another way to get the QU to recognize the drive. If there is, please advise.) The second time, I actually replugged the USB, or jiggled it or something, but then it “saw ” the drive.
5) Near the end of set up, the 2 tk playback (wav files from the drive) just stopped in the middle of a song. When I went to investigate, the QU 24 no longer recognized the drive.)
6) All of this made me wary of being able to record the nights show, so I took the drive home to see if it was a bad cable (it wasn’t) and to see if my home computer had any trouble recognizing the drive (it didn’t.)
7) When I armed the drive to record the show it seemed to arm, but then when I pressed play I saw an error message (can’t remember what it said) it didn’t seem like the elapsed time started, but then it did after a few seconds, so I let it go.

Since I’m playing in the band and not just engineering, I had to let it go. There was no recording when I checked the files at home.

So:
1) Either the problem is that the drive should be formatted before each session, which is OK, but I now know not to use it to play 2 tk files for Preshow/Intermission.
2) Or the drive is in fact NOT a tested drive (the knowledge base says WD 500gig My Passport, but not Ultra. Mine is a 500 gig My Passport Ultra. I’m not sure if that makes a difference)
3) Or there is something wrong with my QU 24 desk?

Based on the description of the problems above, what do you think? Unfortunately, I only have access to the desk at our monthly show, so I wanted to have an idea of how to solve the problem before the next show.

Since I did get one good recording on a freshly formatted drive, I am assuming that is the solution and not that there is a problem with the drive or the desk

Thanks for your help,
David

[Anonymous]

Manufacturers change things without changing the name often enough. If they’ve added an ultra they’ve probably increased sequential performance, maybe at the cost of random access.

Personally – I bought a Sandisk Extreme specifically for the desk (it lives in the flight case) and use an iPod (or similar) to provide inter-set music.

[Andreas]

When using mechanical drives always think about power consumption. Physical drives generally require more power than flash drives. The faster they are (faster moving heads, faster spinning), the more power they require, this is simple physics. The maximum allowed 500mA on a USB 2 port isn’t that much and I have some HDDs which pull considerable more (out of spec).
While the QuDrive port can handle 500mA, trying a separate power supply for physical drives is probably a good choice.

I started to use a somewhat older WD Passport Essential on the Qu which pulls slightly above 500mA. From time to time it hardly spins up any may require a reconnect. Once its up, everything is fine…
…unless I’m waiting too long and the drive’s internal powersafe let it spin down (reconnect required to spin up again)…
Finally I’ve switched to the Extreme as well and benefit from fast enumeration, stable operation etc.

But since I saw too many USB sticks dying, I personally do important recordings on a notebook with the QuDrive performing a (downmixed) parallel recording for backup purposes.

[Nicola A&H]

Hi David,

We had problems with a WD My Passport Ultra USB 3.0 while testing Qu-Drive. It is listed as an unsupported device in the KB article.

[Author]

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