On September 23, 2011, Stan Hoeppner wrote: > On 9/23/2011 11:22 AM, Thomas Fjellstrom wrote: > > I'd love to switch, but I didn't really have the money for the card then, > > and now I have less money. I suppose if I ebayed this card first, and > > then bought a new one that would work out, but yeah, It will have to > > wait a bit (things are VERY tight right now). > > Which is why you purchased the cheapest SAS card on the market at that > time. :) > > > So this Intel card, looks like a good option, but how much faster is it? > > I get 500MB/s read off this SASLP. Probably a bit more now that there's > > 7 drives in the array. Off of XFS, it gets at least 200MB/s read (the > > discrepancy between raw and over xfs really bugs me, something there > > can't be right can it?). > > When properly configured XFS will achieve near spindle throughput. > Recent versions of mkfs.xfs read the mdraid configuration and configure > the filesystem automatically for sw, swidth, number of allocation > groups, etc. Thus you should get max performance out of the gate. What happens when you add a drive and reshape? Is it enough just to tweak the mount options? > If you really would like to fix this, you'll need to post on the XFS > list. Much more data will be required than simply stating "it's slower > by x than 'raw' read". This will include your mdadm config, testing > methodology, and xfs_info output at minimum. There is no simple "check > this box" mega solution with XFS. I tweaked a crap load of settings before settling on what I have. Its reasonable, a balance between raw throughput and directory access/modification performance. Read performance atm isn't as bad as I remember, about 423MB/s according to bonnie++. Write performance is 153MB/s which seems a tad low to me, but still not horrible. Faster than I generally need at any given time. > > Thank you for the suggestion though, I will have to book mark that link. > > You're welcome. > > You can't find a better value for an 8 port SAS or SATA solution that > actually works well with Linux. Not to my knowledge anyway. You could > buy two PCIe x1 4 port Marvell based SATA only cards for $20-30 less > maybe, but would be limited to 500MB/s raw unidirectional PCIe b/w vs > 2GB/s with an x4 card, have less features, eat two slots, etc. That > would be more reliable than what you have now though. The Marvell SATA > driver in Linux is much more solid that the SAS driver, from what I've > read anyway. I've never used/owned any Marvell based cards. If I go > cheap I go Silicon Image. It's too bad they don't have a 4 port PCIe > ASIC in their line up. The only 4 port chip they have is PCI based. > Addonics sells a Silicon Image expander, but the total cost for a 2 port > card and two expanders is quite a bit higher than the better Intel > single card solution. I appreciate the tips. That intel/LSI card seems like the best bet. -- Thomas Fjellstrom tfjellstrom@xxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
