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 <[email protected]>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" <[email protected]> > À: "Muhammad Yousuf Khan" <[email protected]>, "pve-user pve.proxmox.com" < > [email protected]> > 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> > > > _______________________________________________ > pve-user mailing list > [email protected] > http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user >
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