Hi, In a setup similar to yours I changed from a single 15 disks raidz2 to 7 mirros of 2 disks each. The change in performance was stellar. The key point in serving things for VMware is that it always issue synchronous writes, wheter on iscsi or NFS. When you have tens of VM the resulting traffic is always random for the backing store, and random synch writes are the achille's heel for ZFS.
now about your options > 1) Change to iSCSI mounts to ESX, and enable write-cache on the LUN's since > the 7210 is on a UPS. this won't save you from a crash > 2) get a Logzilla SSD mirror. (do ssd's fail, do I really need a mirror?) yes you do need a mirror albeit in a recent thread here it's exposed it's not enough. > 3) reconfigure the NAS to a RAID10 instead of RAIDz this is the way I would go. To make up for the lost space you can enable lz compression (the default one) which should be more or less transparent and leads to very good savings (1,5x - 2x) another advice if your guests are unix: unless you need it, mount your guests OS with noatime, this will reduce basic chatter about 50% in my experience. another thing that helps is to have cache devices, even if they aren't faster than the pool's ones they free up iops that can be used for writes. to summarize I'd go for the mirror setup, then if it's not enough a pair of SSD for SLOG would surely help. Il giorno 27/ago/2010, alle ore 07.04, Mark ha scritto: > We are using a 7210, 44 disks I believe, 11 stripes of RAIDz sets. When I > installed I selected the best bang for the buck on the speed vs capacity > chart. > > We run about 30 VM's on it, across 3 ESX 4 servers. Right now, its all > running NFS, and it sucks... sooo slow. > > iSCSI was no better. > > I am wondering how I can increase the performance, cause they want to add > more vm's... the good news is most are idleish, but even idle vm's create a > lot of random chatter to the disks! > > So a few options maybe... > > 1) Change to iSCSI mounts to ESX, and enable write-cache on the LUN's since > the 7210 is on a UPS. > 2) get a Logzilla SSD mirror. (do ssd's fail, do I really need a mirror?) > 3) reconfigure the NAS to a RAID10 instead of RAIDz > > Obviously all 3 would be ideal , though with a SSD can I keep using NFS for > the same performance since the R_SYNC's would be satisfied with the SSD? > > I am dreadful of getting the OK to spend the $$,$$$ SSD's and then not get > the performance increase we want. > > How would you weight these? I noticed in testing on a 5 disk OpenSolaris, > that changing from a single RAIDz pool to RAID10 netted a larger IOP increase > then adding an Intel SSD as a Logzilla. That's not going to scale the same > though with a 44 disk, 11 raidz striped RAID set. > > Some thoughts? Would simply moving to write-cache enabled iSCSI LUN's > without a SSD speed things up a lot by itself? > -- > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- Simone Caldana _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
