[PVE-User] openiscsi with Proxmox

[Muhammad Yousuf Khan]

Thanks All, it was a very nice and informative discussion,  i learned a lot.

Thanks you.

Myk


On Fri, Jan 3, 2014 at 4:38 PM, Alexandre DERUMIER <aderumier at odiso.com>wrote:

> Hi,
>
> about l2arc, be carefull of your block size.
>
> Because, each block need around 200 bytes of memory to be mapped in l2arc.
> So if you use 4K block size for example,
>
> and you put 1TB of l2arc, you need (1073741824/4 * 0.2) = 54GB of memory.
>
>
>
> ----- Mail original -----
>
> De: "Pongrácz István" <pongracz.istvan at gmail.com>
> À: "Muhammad Yousuf Khan" <sirtcp at gmail.com>, "pve-user pve.proxmox.com" <
> pve-user at pve.proxmox.com>
> Envoyé: Vendredi 3 Janvier 2014 12:27:22
> Objet: Re: [PVE-User] openiscsi with Proxmox
>
>
>
> Hi,
>
>
>
>
>
> [Cut]
> <blockquote>
> SLOG - dedicated device (partition) to hold ZIL on it instead of the pool
> (much quicker than pool -> high iops for sync writes)
>
>
>
>
> first of thanks for writing an informative input.
> as it seems, a person must need 1 SSD for L2ARC and 2xmirrored SSDs for
> ZIL, now the question is do we also need a SSD for SLOG
>
> ZIL is the write cache in memory. SLOG is like a raid1 mirror to ZIL
> located on storage. This could be on dedicated SSD or in a partition on an
> SSD. In your case it could be enough to make some partitions on a reliable
> SSD and use it for system (ext3/4), L2ARC (10-100GB?), SLOG (1-2GB). Please
> remember, only sync writes goes to ZIL, in the worst case you lost 5
> seconds of data if the SLOG device dies too. (no rule of thumb, you need to
> check your implementation details)
>
> Thanks Fabio, i have a dell workstation 490 and it only support SATAv2 or
> 3gb speed.
>
> do you guys think by tweaking ZFS a bit and using multiple SSDs for ZIL,
> L2ARC and may be SLOG can give me 4x1GB from each interface. as i mentioned
> i have 12GB RAM.
>
> No idea. You should play with the tunings (compression, raidz2/3). Too
> much variables (cpu throughput, your pool config, fragmentation of course -
> COW, IO direction). I have a AMD T56N system with 2 x sata port
> multiplicators with 6x 2.5" hitachi disks, I can achieve 50MB/sec write to
> them with no compression - video, but sometimes it droppes to 10-20MB/sec.
> So, you should test your system and monitor it.
>
> we are a small company, not too much reads and writes, we mostly checkin
> checkout our software codes to the VM repositories.
> so i think generally we have less IOPS but yes we have huge files in form
> of VMs and they should be backed up every week and snapshot ZFS on daily
> basis
>
> Raidz2/3 could be ok, depends on numbers of your disks.
>
> so with this load what you guys think, can i achieve 4x1gb Ethernet output?
>
> [Cut]
> </blockquote>
>
>
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