Beiträge von nhenk001

Zitat von subzero79

did not have issues at all mounting in omv the /dev/bcache0 device. I used two virtual disks of 2GB. This is debian9+omv4 in server, not with gnome installed, using the bcache tools from debian repos. A full gnome desktop env should not be installed among omv.

You are right, the GUI was messing with my ability to properly mount the bcache volume. Did not think it would matter enough for a prototype "proof of concept," but apparently it did. Thank you for your help, bcache is now set up.

Zitat von darkarn

Wow, my hardware is clearly way weaker than what you are testing, the difference is huge to say the least!

It might take an enterprise-grade system to register performance increases even with random IO. I am testing a substantial performance hit from a single cached disk on my platform (similar to what I experienced with LVM). The problem seems to happen even when transferring large numbers of small files.

I need to discuss with my head of IT and decide if we want to:

• "YOLO" it and hope it works -or-
• Frankenstein old hardware into a semi-realistic test system (probably going to go with this)

Thank you subzero79 for for your help!

Thank you for having a look!

Bcache is really simple to set up, about 10 commands including directory changes once you have bcache installed. I used these guides nearly verbatim (logged in as root):

• Tech-G - After setting up with this guide I thought that maybe I did something wrong. Getting the drives disconnected was a real challenge so I found the a second guide
• Kernel.org (better setup instructions) - Included instructions for "probing initialization failed: Device or resource busy" issue. Instructions for setup are nearly identical in this guide, but they seem a bit more clear

OMV could see my bcache volume after each setup. It only failed when I attempted to create a shared folder; that's the stage where I got the stack trace from.

Other setup information:

• OMV installed in 8.9 Jessie with GNOME desktop
• Virtual machine running in VirtualBox: 2 cores & 2GB of ram
• Very few packages installed (sudo, bcache, lvm, gparted, maybe one or two more)

Zitat von subzero79

THere is bcache tools in Debian Stretch and bcache module in bpo stretch kernel. There is nothing implemented in omv UI or backend to handle bcache.

This appears to be accurate, from what I can tell I set up bcache correctly in CLI and OMV even recognizes it. As soon as I try to mount it for a shared folder it crashes, though.

I tried LVM's caching feature before bcache because it seemed like it was more reliable and closer to business grade. OMV can mount the logical volumes set up in this program. Unfortuntately, actually performed worse while caching, than with a stand alone spinning disk. I could not get documents to promote into SSD. This blog appears to be correct regarding performance based on my own testing: Nikolaus Rath's Website.

Zitat von tkaiser

I's a great addition if you rely on anachronistic RAID modes (eg. a RAID6) since such a RAID shows high sequential performance but sucks totally at random IO. This is where bcache can shine since it accelerates especially random writes.

This is exactly why I was also looking into OMV/bcache and how I found this thread. I am working on a cloud migration but my company works with very large files (including 4K video) and also super small files that need to be built into sprites. We still need a local server for the speed and upload caching (hybrid solution).

OMV seems more consumer-targeted but has all of the security features we should need. It also seems much easier to use than ClearOS which is marketed to businesses as a MS Server alternative.

It's so close to working with bcache... if I was a developer I might look under the hood and assess how much time it would take to resolve the situation. For any curious users that want to look at the stack trace:

• Error #0:
• exception 'OMV\Exception' with message 'Device '/dev/bcache01' is not available after a waiting period of 10 seconds.' in /usr/share/php/openmediavault/system/blockdevice.inc:486
• Stack trace:
• #0 /usr/share/openmediavault/engined/rpc/filesystemmgmt.inc(609): OMV\System\BlockDevice->waitForDevice(10)
• #1 /usr/share/php/openmediavault/rpc/serviceabstract.inc(528): OMVRpcServiceFileSystemMgmt->{closure}('/tmp/bgstatusIY...', '/tmp/bgoutputrj...')
• #2 /usr/share/openmediavault/engined/rpc/filesystemmgmt.inc(642): OMV\Rpc\ServiceAbstract->execBgProc(Object(Closure), NULL, Object(Closure))
• #3 [internal function]: OMVRpcServiceFileSystemMgmt->create(Array, Array)
• #4 /usr/share/php/openmediavault/rpc/serviceabstract.inc(124): call_user_func_array(Array, Array)
• #5 /usr/share/php/openmediavault/rpc/rpc.inc(86): OMV\Rpc\ServiceAbstract->callMethod('create', Array, Array)
• #6 /usr/sbin/omv-engined(536): OMV\Rpc\Rpc::call('FileSystemMgmt', 'create', Array, Array, 1)
• #7 {main}

I really wish this worked, a couple of us at the office were really excited to do a Linux file-server deployment... now we're a little less excited because we have to sell the value/benefits of very large SSD's to the decision makers, haha.