Proxmox VE 3.4 released!

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As i've got to answer some questions in our company (being not a guru but the most experienced zfs user), i'd like to share some answers/best practices, especially according to speed up things with SSDs.

Really great source i've found answering most all basic questions: http://constantin.glez.de/blog/2011/02/frequently-asked-questions-about-flash-memory-ssds-and-zfs

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[h=3]Should I mirror flash memory drives?[/h] Interesting question. On one hand, hardware breaks all the time, and SSDs are no exception. On the other hand, SSDs don't have any moving parts and so they're statistically much less susceptible to failures.
It really depends on your risk tolerance:

  • The ZIL is the last resort to go to if the system crashes before data that was promised to the application to be "safe" is actually written to disk. Then, upon reboot, the system reads back the ZIL and performs the missing updates on the actual ZFS storage pool. Since the ZIL is so important for ensuring data integrity, it should therefore be mirrored and ZFS supports that quite nicely.
  • The L2ARC is a read cache: It stores data for convenience and speed only, but every bit of data in the L2ARC is also available elsewhere. So mirroring an L2ARC SSD is not really necessary (though Marcelo has a very good point in that a dramatic loss of performance may actually justify an L2ARC mirror). Instead, ZFS will use any extra SSDs you give it for L2ARC in order to expand the amount of space for caching data.
[h=3]Can I use the same SSD both as a ZIL and as an L2ARC?[/h] Yes, you can. (I always wanted to say that phrase, btw...)
In theory you can split up an SSD into two slices through the format(1M) command.
In practice, this means that you'll have two streams of data (ZIL writes and L2ARC writes and reads) instead of one, competing for the limited resources of the SSD's connection and controller. That may compromise your ZIL performance as two mechanisms step on each other's feet.
Better try it out: split up the SSD, configure the ZIL part of it, see how much it improves your write performance, then hook up the L2ARC part, while observing if the ZIL performance is still good. Use zilstat for monitoring ZIL performance.


[h=3]How much space do I need for a ZIL?[/h] The role of the ZIL is to store a transaction group until it has safely been written to disk. After that, this can be safely deleted and the space used for the next transaction group.
So the question becomes: How much transaction group data is "in flight" (i.e. not yet written to disk) at any time?
ZFS issues a new transaction group (and consequently a new pool update) every 5 seconds at the latest (more if the load is higher). While one transaction group is written to the ZIL, the previous one may still be in the process of being written to disk, so we need enough space to store two transaction groups, which means 10 seconds of maximum write throughput worth of data.
What's the maximum amount of data that your server writes in 10 seconds? Well, an upper boundary would be the maximum write speed of your SSD. At the time of this writing this was about 170 MB/s for an Intel X25-E, times 10 that would be just short of 2 GB for a typical ZIL.
So for ZILs, a little can go a long way.

[h=3]How much space do I need for an L2ARC?[/h] This is more difficult, or more easy, depending on how you put it. More is always better, but too much would be a waste if it's not used. Check your L2ARC usage with arc_summary and if you still see a significant amount of ghosts after adding an L2ARC, you'll likely benefit from even more L2ARC space.
Another way to estimate L2ARC need is by looking at your working set: The amount of data that is used most frequently. Depending on your application, this could be your top 10 research projects, your top 20% of recurring customers, your most popular 100 products etc.

More hints an sharing SSD for both jobs:



  • ZIL devices should be low-capacity, low-latency devices capable of high IOPS. They are typically mirrored.
  • L2ARC devices should be high-capacity (within reason: You need to add RAM as L2ARC size increases). They scale by striping.

One thing to keep in mind is that the ZIL should be mirrored to protect the speed of the ZFS system. If the ZIL is not mirrored, and the drive that is being used as the ZIL drive fails, the system will revert to writing the data directly to the disk, severely hampering performance.
 
Hi,I installed proxmox on Hp DL380G6 on SDcard 64 Gb, setup ends without error but at boot i have grub error:Attempting boot from usb drivekey (C:)error:grub error attempt to read or write outside of disk hd0entering rescue modegrub rescue>same configuration with proxmox 3.3 o problem (add uin grub.conf rootdelay=10)Any ideaThanksClaudio
 
I have updated Proxmox and now I'm getting error on vnc console: ClassNotFoundException com.tigervnc.vncviewer.VncViewer. Anyone knows how to repair it?
proxmox-ve-2.6.32: 3.3-147 (running kernel: 2.6.32-34-pve)
pve-manager: 3.4-1 (running version: 3.4-1/3f2d890e)
pve-kernel-2.6.32-32-pve: 2.6.32-136
pve-kernel-2.6.32-37-pve: 2.6.32-147
pve-kernel-2.6.32-34-pve: 2.6.32-140
lvm2: 2.02.98-pve4
clvm: 2.02.98-pve4
corosync-pve: 1.4.7-1
openais-pve: 1.1.4-3
libqb0: 0.11.1-2
redhat-cluster-pve: 3.2.0-2
resource-agents-pve: 3.9.2-4
fence-agents-pve: 4.0.10-2
pve-cluster: 3.0-16
qemu-server: 3.3-20
pve-firmware: 1.1-3
libpve-common-perl: 3.0-24
libpve-access-control: 3.0-16
libpve-storage-perl: 3.0-31
pve-libspice-server1: 0.12.4-3
vncterm: 1.1-8
vzctl: 4.0-1pve6
vzprocps: 2.0.11-2
vzquota: 3.1-2
pve-qemu-kvm: 2.1-12
ksm-control-daemon: 1.1-1
glusterfs-client: 3.5.2-1
 
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I have cleaned my browser, I have tried from different computer, with other OS, same error. /usr/share/pve-manager/root is empty, maybe vnc is erased or something.
 
For me this has broke PCI pass through. Going back to the previous kernel fix's the issue. VM simply will not boot with PCI pass through and the latest kernel.
 
Hi,
I am a complete newby to Proxmox. My situation is as follows (home server):
-installing on a hp xw 6400 which has:
- 4 sata's: 1xdvdrom, 3 x hdd's (2x250GB + 1x500GB
-1 IDE, on which I have connected a SSD 16 GB sata through SATA to IDE convertor interface.
-I have installed the Proxmox on this SSD, since I want to passthrough the hdd's to my vm, which will be Univention Server which I would like to install on the pve/local storage
...now I have a strange effect after installation ... during installation the "full 16GB" were recognized by the proxmox installer, but after installation it says that the ssd has only 7.5 GB capacity. So after uploading the iso, there is only 5GB left.
Since I want to install this UCS server also on the local storage (I want to give it 10 GB), this is not possible since there seems to be unsufficient space.
What can be the cause of this error?
And secondly, I am trying to find out the logical steps of installing the storage after proxmox was installed... do I have to mount the hdd's to proxmox, or can I pass them straight through to the vm Univention server, which will be the complete LAN server (file, mail, etc...). I want to use ZFS filesystem, which is supported by UCS, so I suppose I can format the hdd's from within the vm?
Apart from the vm LAN server, I will perhaps have one vm more, being Sophos as a complete firewall system (instead of proxmox firewall, but I am not yet decided)
As storage, I was thinking to put the 2 x 250GB in raidz ZFS for important data, and the 500GB hdd for other data like videos, or pictures, so not that important.
And I have also 2 usb external hdd's, which I would like to passthrough to the vm UCS.
 
Hi,

the new feature "start all VMs" does only work, if we loggedin as root. if we use a proxmox administrator account, the function does not work. error message: no rights - access forbidden. do you update this function in next version -for proxmox administrators- or it´s a bug?

regards
 
Hi Udo,

thanks for replying me.
The output (partially concerning the 16GB SSD) of "parted -l" is:

Model: ATA Sunspeed TSAM2TE (scsi)
Disk /dev/sda: 15.8GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 1049kB 2097kB 1049kB Grub-Boot-Partition bios_grub
2 2097kB 136MB 134MB fat32 EFI-System-Partition boot, esp
3 136MB 15.8GB 15.7GB PVE-LVM2-Partition lvm

Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/pve-data: 8179MB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags:

Number Start End Size File system Flags
1 0.00B 8179MB 8179MB ext3


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/pve-swap: 1879MB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags:

Number Start End Size File system Flags
1 0.00B 1879MB 1879MB linux-swap(v1)


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/pve-root: 3758MB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags:

Number Start End Size File system Flags
1 0.00B 3758MB 3758MB ext3



The output "pvs"

PV VG Fmt Attr PSize PFree
/dev/sda3 pve lvm2 a-- 14.61g 1.75g

The output for "vgs":

VG #PV #LV #SN Attr VSize VFree
pve 1 3 0 wz--n- 14.61g 1.75g

And the output for "lvs":

LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
data pve -wi-ao--- 7.62g
root pve -wi-ao--- 3.50g
swap pve -wi-ao--- 1.75g

Hope you can help me out with this issue.
Thanks Hugo
 
Hi, this seems to be the finest of all releases of proxmox, but I am having problem. I downloaded the iso, checked the sum and all ok. Burnt using dd (in linux) to both USB stick and SD card, all went well. But when I try to boot, I am repeatedly getting a grub error which reads:

error: disk `' not found.
Enterning resuce mode ...
grub rescue>

The proxmox installer does not seem to get launched. Any clue? Thanks!
 
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