Does someone have any idea? I run again into this and it is really frustrating 
You're running an old version of OMV with out of date software which you should have updated to OMV5 then OMV6 log ago.
I'm not sure what "check" you are referring to and perhaps you mean re-sync rather than rebuild. If you can ssh into your OMV install, then you can use "top" to see if any particular process is hogging your machine when the WebUI becomes unavailable. While you are the CLI, you can always look at the output of cat /proc/mdstat to check the health of your md arrays.
Is your hardware the reason of your problems ? I refer to your own post: RE: Kernel ATA Error Messages while using HDD Cache
Is your hardware the reason of your problems ? I refer to your own post: RE: Kernel ATA Error Messages while using HDD Cache
Good catch. I think it is possible. Thats why I wanted to ask if others are seeing my problems as well.
Maybe starting a new thread asking about the DeLOCK 8938 card would grab people's attention rather than tagging onto an old thread. But the message I take from the old thread is to just to ditch the DeLOCK and get yourself a server grade RAID card capable of running as a pure Host Bus Adapter (HBA) in IT mode. One card will support 8 drives.
I've no idea how your hardware is setup. Whether you're using consumer or server grade parts, nor what kind of case and cooling you're using, nor how your 10 HDDS are combined.
Among other things you can see in top is the kind of iowaits your system has. Things point to the DeLOCK 8938 card as a possible bottle neck and perhaps even a source of file errors.
OK you've got your answer as to why the DeLOCK card is bad for your setup.
QuoteJust got response from DeLock (very quick response!):
2x JMB575 and 1x ASM1062 chip is being used on DeLOCK 89384 (current model).
JMB575 is a port multiplier chip and not suitable for RAID applications. Just google JMB575 + RAID.
Maybe starting a new thread asking about the DeLOCK 8938 card would grab people's attention rather than tagging onto an old thread. But the message I take from the old thread is to just to ditch the DeLOCK and get yourself a server grade RAID card capable of running as a pure Host Bus Adapter (HBA) in IT mode. One card will support 8 drives.
I've no idea how your hardware is setup. Whether you're using consumer or server grade parts, nor what kind of case and cooling you're using, nor how your 10 HDDS are combined.
Among other things you can see in top is the kind of iowaits your system has. Things point to the DeLOCK 8938 card as a possible bottle neck and perhaps even a source of file errors.
I was wasting so many days, weeks, maybe even months of searching the internet and trying out stuff. You took the right conclusion in few hours. Yes, you are right. This card messed up everything. I already ordered LSI Broadcom 9300 16i card.
OK you've got your answer as to why the DeLOCK card is bad for your setup.
JMB575 is a port multiplier chip and not suitable for RAID applications. Just google JMB575 + RAID.
I didnt know port multiplier is a problem with RAID. I have seen a lot of complain about the kernel errors I experienced, because I was googling like hell. It seems you know a lot more than many admins out there.
I didn’t get a chance to add to my previous comment before you decided to purchase a replacement for the DeLock SATA card. So I may be too late with these few thoughts.
It’s not hard to find consumer computer parts on sale which are of dubious design and/or quality whether that’s on Amazon, AliExpress, Ebay or normal retail channels. The DelocK card basically uses a two channel SATA chip (ASM1062 ) with each channel linked to a port multiplier ( JMB575). That’s 2x5, giving 10 ports.
This is like having five HDDs working off a single SATA port, all waiting their turn for IO. Once the HDDs are combined in software RAID they need simultaneous access which the card design doesn’t adequately support. Hence the horrible performance.
When it comes to buying a SATA card to increase the number of ports above those on your m/board, it’s a case of buyer beware. You need to check the chipsets actually used, eg. Marvell, Jmicron, ASMedia, and how they are combined.
There a couple of things to consider for anyone thinking of buying/using a server grade HBA, which are often s/hand.
1. Watch out for fakes.
2. They need adequate cooling as they were designed to be used in high air flow server kit.
3. They introduce a single point of failure.
To mitigate point 3, with one 8 port card & mirror RAID10 connect one side of the mirror to one 4 port channel and the other mirror side to the second channel and so on.
Last but not least, as you have 10 HDDs in some kind of RAID configuration, all ten in a single RAID5 is a bad choice. Loose a single drive and your array becomes fragile, a further problem during a long re-sync, or a second HDD is kicked out and that spells disaster and a lengthy restore. Consider using RAID6 limited to eight drives and hold two spares if high availability is the aim. If you data has different usage patterns, e.g. some volatile but other data mostly static, then segregation may offer better choices for how to combine your drives.
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I didn’t get a chance to add to my previous comment before you decided to purchase a replacement for the DeLock SATA card. So I may be too late with these few thoughts.
It’s not hard to find consumer computer parts on sale which are of dubious design and/or quality whether that’s on Amazon, AliExpress, Ebay or normal retail channels. The DelocK card basically uses a two channel SATA chip (ASM1062 ) with each channel linked to a port multiplier ( JMB575). That’s 2x5, giving 10 ports.
This is like having five HDDs working off a single SATA port, all waiting their turn for IO. Once the HDDs are combined in software RAID they need simultaneous access which the card design doesn’t adequately support. Hence the horrible performance.
When it comes to buying a SATA card to increase the number of ports above those on your m/board, it’s a case of buyer beware. You need to check the chipsets actually used, eg. Marvell, Jmicron, ASMedia, and how they are combined.
There a couple of things to consider for anyone thinking of buying/using a server grade HBA, which are often s/hand.
1. Watch out for fakes.
2. They need adequate cooling as they were designed to be used in high air flow server kit.
3. They introduce a single point of failure.
To mitigate point 3, with one 8 port card & mirror RAID10 connect one side of the mirror to one 4 port channel and the other mirror side to the second channel and so on.
Last but not least, as you have 10 HDDs in some kind of RAID configuration, all ten in a single RAID5 is a bad choice. Loose a single drive and your array becomes fragile, a further problem during a long re-sync, or a second HDD is kicked out and that spells disaster and a lengthy restore. Consider using RAID6 limited to eight drives and hold two spares if high availability is the aim. If you data has different usage patterns, e.g. some volatile but other data mostly static, then segregation may offer better choices for how to combine your drives.
This is the post I should have received many years ago.
My setup is very special. I have two SSDs for system in RAID1 (OMV is normally installed on one disk). I have 3x disks in RAID5 for Nextcloud and backups (I have written scripts to create a backup before upgrades), 5x disks in RAID5 for my media and 2x disks in RAID0 for everything that needs speed. So no, not all disks are in one array!
The LSI card should be the right one. How to see if it is fake? https://www.ebay.de/itm/195717998105
Many thanks!
Edit: channels, ports, IT mode, full duplex, port multiplier....this storage topic isnt easy at all!
The 9300-16i runs EXTREMELY hot! It's technically 2 packages (2 8-ports). I'd be weary for smaller builds. For a time I had it replaced with a 9305-16i which ran ~15c cooler.
godfuture Your data appears to be well segregated. It's pity you need that RAID0, or can't connect it to SATA ports on your m/board, otherwise a single 8 port controller would suffice.
I'm more familiar with the earlier generation of SAS 2008/2308 type 8 port cards. Ten or twelve years ago when homeserver users were buying these for their unRAID and FreeNAs, etc., builds, some purchasers were not aware of the Far-East copies that were on sale. It may be that some of these copies were unofficial over-runs produced in the same factories as the originals, but they seemed/were inferior in quality. Naturally they thought they had bought and paid for genuine original cards and dubbed these copies "fakes" or "counterfeits".
A 9300-16I card would not be my choice for a homeserver as @olduser is right point out the power they consume and the heat they generate. You could easily burn a finger if you touched the heatsink. They would need careful active fan cooling if used in a typical home pc case.
I would not like to swear your link points to a genuine card, superficially it appears to be OK. It looks the same as the the card from this trusted UK source https://www.ebay.co.uk/itm/204…05bced:g:dBEAAOSwagtkKYFc
The board I am using only has one 16x PCIe, all other are just 1x. There is a long story behind it, but to make it short, two important points that led me into this: price and transcoding.
What about moving the RAID0 to a 2port SATA card running of the x1 slot and using a 8 port controller card in the x16 slot? You had have to work if there's enough pcie lanes on your setup to service the two card. It shouldn't be too hard to find a decent 2 port SATA card.
Should there not be a guide in hardware section of this forum that excatly explains these things to beginners?
I think it could save a lot of time and prevent many issues that are being reported here in different threads as symptoms of the core problem.
It would be helpful if such a guide existed. Any member of the forum can contribute to the guides section, guides are always welcome.
The 9300-16i runs EXTREMELY hot! It's technically 2 packages (2 8-ports). I'd be weary for smaller builds. For a time I had it replaced with a 9305-16i which ran ~15c cooler.
I could cancel my order. I had luck due to Chinese holidays. The cheapest 9305-16i incl. cables was 190€, but I have found 9500-16i for 243€. Lower power consumption 24/7 will pay off over years. Therefore I think the better option...also having the better product in the end.
Many thanks for all the support. I finally figured out what stressed me since I started to selfhost. 
I can confirm. Since I swapped my DeLOCK 89384 with LSI 9500-16i, all issues with hanging UI are gone.
Many thanks for all the support. Very happy now 
I hope this thread can help others also being fooled by cheap sata controller.
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