LXC and Trim

[MisterY]

Hi,

I'm using Proxmox 4.4 with two ZFS-Pools.
First I tried using VMs, but since the vDisks are too slow and using TRIM is hard to get working, I switched to LXC and Mountpoints. It is really fast and I thought the TRIM problem is gone since I'm using the disks in the host directly. But now I see that the LXC is using 160GB of space, while only 80GB are stored in the MP.
Why is this so? And how can I get rid of this too much used space?

 

[Rhinox]

If you store VM/LXC on zfs-pool, bear in mind that zfs on linux does not support TRIM yet...

 

[MisterY]

great...and how do I prevent my ZFS-Pool from getting flooded even if it's empty?

and why is the used storage space decreasing after deleting some files?

 

[dcsapak]

But now I see that the LXC is using 160GB of space, while only 80GB are stored in the MP.

are you using snapshots?

 

[MisterY]

yes, but not for this LXC.

 

[Rhinox]

great...and how do I prevent my ZFS-Pool from getting flooded even if it's empty?

That should be your least concern. More serious problem of missing "trim" is performance degradation over time. R/W-speed can drop to fraction of what SSD had as new. Consumer-SSDs are severely impacted by this, but even high-end industry-level SSDs suffer. The only solution (except of moving to other FS/OS with trim-support) is to increase overprovisioning to at least 25%...

 

[guletz]

I read a lot of stories about trim. But I see with my own eyes this:

- several Intel ssd (datacenter series) used for at least 2 years, without any overprovision, with zfs do not have any problems regarding speed for Write.

- the same experience with consumer SSD , including 3 intel ssd (3 years usage each of them for 24 h/24)

Maybe I am a luky guy?

 

[MisterY]

the performance degrading isn't my first concern. Actually I'm a bit upset how it is possible to release such an unfinished filesystem with one of the basic options a filesystem should have??
How worth is a filesystem that is flooded with data because it can't reuse blocks?! wtf?!
Actually I was happy with Proxmox + ZFS but, sorry, this is kinda sh**. I can't buy everytime new harddrives only because the filesystem is too stupid to reuse the old blocks?!
So what can I do to use the (basic option) TRIM to get rid of the flooded disks??

Please don't misunderstand me - Proxmox is a very cool OS and I like it very much. And the last option for me should be a change to esxi or something like this. I'm not upset because of Proxmox, I'm upset because of ZFS...

edit: And why is only 1.4TB available? I made a ZFS-Raidz1 out of 3 1TB disks. shouldn't it have to be 2TB??

 

[guletz]

Actually I'm a bit upset how it is possible to release such an unfinished filesystem with one of the basic options a filesystem should have?

Remember that zfs was invented 12 years ago. Nothing is perfect in any piece of software . It was a proposal some time ago, when a french guy if I remember was start to work to a patch for ssd trim.
Until something will be released , you could send your ssd pool to another pool. Then you can trim your ssd. Then import the data. If you use a zvol for ssd, then any fstrim will do the job if the fs has support (like ext4).