[Users] SSD trim support over a LUKS layer

Narcis Garcia informatica at actiu.net
Sat Apr 27 20:14:56 MSK 2019


I responded about OpenVZ/6 vs LXC, and Proxmox doesn't solve the Discard
issue for OpenVZ/6 with a LUKS layer.

With any of Devuan 1, 2, Debian 8, 9 kernels, Discard works fine with
LUKS layer (with or without LXC), and Proxmox doesn't help in this.


El 27/4/19 a les 16:39, spameden ha escrit:
> Furthermore there might be issues using old legacy OpenVZ6 kernel on
> modern hardware, e.g. NVMe or any newer NIC cards.
> 
> Seeing as you've been using Debian as well as me for quite some time I'd
> recommend - https://proxmox.com 
> 
> In proxmox you can use unprivileged LXC containers (for security) as
> well as containers with directory storage though they don't support
> quotas (but you save on precious nvme disk storage).
> 
> There is also fancy webui, but I don't use it, mainly sticking to the
> console pct tool and template's system.
> 
> There is a bit hassle regarding using external IPs in the containers,
> but it's possible via certain workaround with iptables and routing.
> 
> Proxmox also works natively with latest Debian Stretch (with systemd)
> and it's using recent kernel, e.g.:
> 
> # uname -r
> 4.15.18-12-pve
> 
> and yes discards work just fine on proxmox:
> 
> # dmsetup table|grep discards
> ***: 0 123 crypt aes-xts-plain64
> 0000000000000000000000000000000000000000000000000000000000000000 0 9:1
> 4096 1 allow_discards
> 
> Migration from OpenVZ6 is also very straightforward to Proxmox: in most
> cases containers just do work (if you've been using simfs before) and
> not requiring any modifications.
> 
> 
> 
> сб, 27 апр. 2019 г. в 17:28, CoolCold <coolthecold at gmail.com
> <mailto:coolthecold at gmail.com>>:
> 
>     I believe to have fixes and backports like this in to legacy version
>     of product will not happen, and you should consider upgrading.
>     Personally, I've upgraded to lxc.. it's quite primitive comparing to
>     ovz 6, but it's enough for my needs.
> 
>     On Sat, Apr 27, 2019, 17:49 spameden <spameden at gmail.com
>     <mailto:spameden at gmail.com>> wrote:
> 
>         Yes, it's an issue in kernel. 
> 
>         As dm-crypt/luks layer isn't passing TRIM to the underlying device.
> 
>         /boot is not encrypted that's why it works for you.
> 
>         сб, 27 апр. 2019 г. в 11:11, Narcis Garcia
>         <informatica at actiu.net <mailto:informatica at actiu.net>>:
> 
>             See in the case that /dev/sda1 (Directly mounted as Ext4 on
>             /boot) works with Trim/Discard.
>             It's the sda2_crypt (layer over sda2) that is not detected
>             to be trimmable. Devuan's stock kernel does.
> 
>             CentOS issue #6548 may not be this same bug; I've tested now
>             with CentOS 6.8 with a similar (but not same) result*:*
> 
>             $ lsb_release -d
>             Description:    CentOS release 6.8 (Final)
> 
>             $ uname -a
>             Linux localhost.localdomain 2.6.32-642.el6.x86_64 #1 SMP Tue
>             May 10 17:27:01 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
> 
>             $ lsblk --discard /dev/sda
>             NAME                                                
>             DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
>             sda                                                        
>             0      512B       2G         0
>             ├─sda1                                                     
>             0      512B       2G         0
>             └─sda2                                                     
>             0      512B       2G         0
>               └─luks-f691f48b-8556-487d-ac64-50daa99ed4c9 (dm-0)       
>             0      512B       2G         0
> 
>             $ cat /etc/crypttab
>             luks-f691f48b-8556-487d-ac64-50daa99ed4c9
>             UUID=f691f48b-8556-487d-ac64-50daa99ed4c9 none luks,discard
> 
>             $ mount | grep -e discard
>             /dev/mapper/luks-f691f48b-8556-487d-ac64-50daa99ed4c9 on /
>             type ext4 (rw,discard)
>             /dev/sda1 on /boot type ext4 (rw,discard)
> 
>             $ sudo fstrim /boot
>             # (same result as Devuan/1 and OpenVZ/6 kernel: success)
> 
>             $ sudo fstrim /
>             fstrim: /: FITRIM ioctl failed: Operation not supported
> 
> 
>             El 26/4/19 a les 21:36, spameden ha escrit:
>>             Hi.
>>
>>             I've asked this question years ago (in
>>             2013): https://lists.openvz.org/pipermail/users/2013-August/005250.html
>>
>>             Let me know if it helps, but this bug should have been
>>             fixed in CentOS and RHEL at
>>             least: https://bugs.centos.org/view.php?id=6548
>>
>>             Maybe OpenVZ maintainers didn't pick up this fix in the
>>             openvz6 legacy kernel?
>>
>>             Thanks.
>>
>>             ср, 10 апр. 2019 г. в 10:45, Narcis Garcia
>>             <informatica at actiu.net <mailto:informatica at actiu.net>>:
>>
>>                 Does anybody know how can I solve this?
>>
>>                 $ lsb_release -d
>>                 Description:    Devuan GNU/Linux 1.0 (jessie)
>>
>>                 $ uname -a
>>                 Linux bell1 2.6.32-openvz-042stab134.8-amd64 #1 SMP
>>                 Fri Dec 7 17:18:40
>>                 MSK 2018 x86_64 GNU/Linux
>>
>>                 $ lsblk --discard /dev/sda
>>                 NAME           DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
>>                 sda                   0      512B       2G         0
>>                 ├─sda1                0      512B       2G         0
>>                 └─sda2                0      512B       2G         0
>>                   └─sda2_crypt        0        0B       0B         0
>>
>>                 $ cat /etc/crypttab
>>                 sda2_crypt UUID=***** none luks,discard
>>
>>                 $ mount | grep -e discard
>>                 /dev/mapper/sda2_crypt on / type ext4
>>                 (rw,noatime,errors=remount-ro,barrier=1,data=ordered,discard)
>>                 /dev/sda1 on /boot type ext4
>>                 (rw,relatime,barrier=1,data=ordered,discard)
>>
>>                 $ sudo fstrim /
>>                 fstrim: /: the discard operation is not supported
>>
>>                 Thank you.
>>
>>
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