nice, in other words, is better spend money with hardware raid cards right? any special card that i should look? 2013/9/18 Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>: > On 9/18/2013 12:33 PM, Roberto Spadim wrote: >> Well the internet link here is 100mbps, i think the workload will be a >> bit more than only 100 users, it's a second webserver+database server >> He is trying to use a cheaper server with more disk performace, Brazil >> costs are too high to allow a full ssd system or 15k rpm sas harddisks >> For mariadb server i'm studing if the thread-pool scheduler will be >> used instead of one thread per connection but "it's not my problem" >> the final user will select what is better for database scheduler >> In other words i think the work load will not be a simple web server >> cms/blog, i don't know yet how it will work, it's a black/gray box to >> me, today he have sata enterprise hdd 7200rpm at servers (dell server >> r420 if i'm not wrong) and is studing if a ssd could help, that's my >> 'job' (hobby) in this task > > Based on the information provided it sounds like the machine is seek > bound. The simplest, and best, solution to this problem is simply > installing a [B|F]BWC RAID card w/512KB cache. Synchronous writes are > acked when committed to RAID cache instead of the platter. This will > yield ~130,000 burst write TPS before hitting the spindles, or ~130,000 > writes in flight. This is far more performance than you can achieve > with a low end enterprise SSD, for about the same cost. It's fully > transparent and performance is known and guaranteed, unlike the recent > kernel based block IO caching hacks targeting SSDs as fast read/write > buffers. > > You can use the onboard RAID firmware to create RAID1s or a RAID10, or > you can expose each disk individually and use md/RAID while still > benefiting from the write caching, though for only a handful of disks > you're better off using the firmware RAID. Another advantage is that > you can use parity RAID (controller firmware only) and avoid some of the > RMW penalty, as the read blocks will be in controller cache. I.e. you > can use three 7.2K disks, get the same capacity as a four disk RAID10, > with equal read performance and nearly the same write performance. > > Write heavy DB workloads are a post child for hardware caching RAID devices. > > -- > Stan > > > > >> 2013/9/18 Drew <drew.kay@xxxxxxxxx>: >>> On Wed, Sep 18, 2013 at 8:51 AM, Roberto Spadim <roberto@xxxxxxxxxxxxx> wrote: >>>> Sorry guys, this time i don't have a full knowledge about the >>>> workload, but from what he told me, he want fast writes with hdd but i >>>> could check if small ssd devices could help >>>> After install linux with raid1 i will install apache mariadb and php >>>> at this machine, in other words it's a database and web server load, >>>> but i don't know what size of app and database will run yet >>>> >>>> Btw, ssd with bcache or dm cache could help hdd (this must be >>>> enterprise level) writes, right? >>>> Any idea what the best method to test what kernel drive could give >>>> superior performace? I'm thinking about install the bcache, and after >>>> make a backup and install dm cache and check what's better, any other >>>> idea? >>> >>> We still need to know what size datasets are going to be used. And >>> also given it's a webserver, how big of a pipe does he have? >>> >>> Given a typical webserver in a colo w/ 10Mbps pipe, I think the >>> suggested config is overkill. For a webserver the 7200 SATA's should >>> be able to deliver enough data to keep apache happy. >>> >>> In the database side, depends on how intensive the workload is. I see >>> a lot of webservers where the 7200's are just fine because the I/O >>> demands from the database are low. Blog/CMS systems like wordpress >>> will be harder on the database but again it depends on how heavy the >>> access is to the server. How many visitors/hour does he expect to >>> serve? >>> >>> >>> -- >>> Drew >>> -- >>> 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 >> >> >> > -- Roberto Spadim -- 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
