May 10, 201610 yr I'm looking to take 2 SSDs from my current 4 disk RAID10 cache pool and turn them into 2 RAID 0 cache pools (on separate servers obviously). First off, does UnRAID v6 support RAID 0 cache pools now (I know they didn't during the beta)? If so, what's the procedure for removing 2 disks and converting the pool to RAID 0?
May 10, 201610 yr You have to manually specify the balance level on each and every reboot to have a raid0 btrfs setup.
May 10, 201610 yr Author You have to manually specify the balance level on each and every reboot to have a raid0 btrfs setup. Hmmm that's no good. So there's no way to get higher than single drive read/writes speeds in a 2 drive cache pool?
May 11, 201610 yr Community Expert You have to manually balance to raid0 the first time, but it will survive a reboot, only if you add another device to the pool you need to rebalance.
May 11, 201610 yr Author You have to manually balance to raid0 the first time, but it will survive a reboot, only if you add another device to the pool you need to rebalance. Are you sure about this? I've heard conflicting information that for some it survives reboot and others it doesn't.
May 11, 201610 yr Community Expert You have to manually balance to raid0 the first time, but it will survive a reboot, only if you add another device to the pool you need to rebalance. Are you sure about this? I've heard conflicting information that for some it survives reboot and others it doesn't. Yes, I've used raid0/raid5/raid6.
May 11, 201610 yr Author You have to manually balance to raid0 the first time, but it will survive a reboot, only if you add another device to the pool you need to rebalance. Are you sure about this? I've heard conflicting information that for some it survives reboot and others it doesn't. Yes, I've used raid0/raid5/raid6. Thank you for confirming that johnnie. What have your experiences been with these different RAID configs and what are you running now?
May 11, 201610 yr Community Expert At the moment I'm running cacheless, I don't use VMs and with turbo write and/or lots of RAM don't need it on my servers, but didn't have any issues with the other modes.
May 11, 201610 yr Author At the moment I'm running cacheless, I don't use VMs and with turbo write and/or lots of RAM don't need it on my servers, but didn't have any issues with the other modes. I thought turbo write was only something to be used temporarily but not full time? Can you elaborate on how you're using it?
May 11, 201610 yr At the moment I'm running cacheless, I don't use VMs and with turbo write and/or lots of RAM don't need it on my servers, but didn't have any issues with the other modes. I thought turbo write was only something to be used temporarily but not full time? Can you elaborate on how you're using it? It all depends on your individual usage models and server setups.
May 11, 201610 yr Author At the moment I'm running cacheless, I don't use VMs and with turbo write and/or lots of RAM don't need it on my servers, but didn't have any issues with the other modes. I thought turbo write was only something to be used temporarily but not full time? Can you elaborate on how you're using it? It all depends on your individual usage models and server setups. Is there any documentation that elaborates on this? I'm very interested.
May 11, 201610 yr Community Expert Turbo writes biggest disadvantage is requiring all disks to spun up for writes, but since most of my servers are always off and I only turn them on a couple of hours once a week to copy data, it's not an issue for me, and data is written at or very close to gigabit speed. There's a good explanation about it here: https://lime-technology.com/forum/index.php?topic=47839.msg458455#msg458455
May 19, 201610 yr Author Ok finally got around to removing 2 of my cache pool drives so now I'm down to 2 from 4. I ran a rebalance (raid1) and now I'm trying to re-balance to raid0 but when I run -dconvert=raid0 -mconvert=raid0 and hit balance the page just refreshes and nothing happens. Am I missing something? EDIT: Ahh, just found this in the logs. BTRFS error (device sdg1): balance will reduce metadata integrity, use force if you want this
May 19, 201610 yr Community Expert Ok finally got around to removing 2 of my cache pool drives so now I'm down to 2 from 4. I ran a rebalance (raid1) and now I'm trying to re-balance to raid0 but when I run -dconvert=raid0 -mconvert=raid0 and hit balance the page just refreshes and nothing happens. Am I missing something? EDIT: Ahh, just found this in the logs. BTRFS error (device sdg1): balance will reduce metadata integrity, use force if you want this I think the usual way is to -dconvert=raid0 -mconvert=raid1
May 19, 201610 yr Author Ok finally got around to removing 2 of my cache pool drives so now I'm down to 2 from 4. I ran a rebalance (raid1) and now I'm trying to re-balance to raid0 but when I run -dconvert=raid0 -mconvert=raid0 and hit balance the page just refreshes and nothing happens. Am I missing something? EDIT: Ahh, just found this in the logs. BTRFS error (device sdg1): balance will reduce metadata integrity, use force if you want this I think the usual way is to -dconvert=raid0 -mconvert=raid1 I see. Will this affect read/write speeds at all (trying to maximize performance across 10Gb network)?
May 19, 201610 yr Community Expert Data will be converted to raid0, metadata will stay raid1, safer and it won't reduce performance/capacity.
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