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Performance tuning: Do Multiple hard disks have an impact?

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Author	Message
Xavier Dutoit	Tuesday 24 January 2006 3:03:32 am Dear all, I was wondering if you have several disks on your server and if you have noticed a performance impact by trying to split the load between several disks. For instance, have you seen a difference if the database is in one hard disk and the apache files on the other ? Put the cache files on a different disk than the templates ? I've got a new server with two disks and I was wondering how to split the things between the two, any suggestion more than welcome. X+ http://www.sydesy.com
Łukasz Serwatka	Tuesday 24 January 2006 3:51:23 am Hi Xavier, By "new server" you mean, "good computer" or "truly" server? ;) If you have two identical disks and your motherboard has built in RAID controller (or use external), then create RAID 0 array. You will gain nice performance boost. Personal website -> http://serwatka.net Blog (about eZ Publish) -> http://serwatka.net/blog
Xavier Dutoit	Tuesday 24 January 2006 4:23:58 am Hi Lukasz, By new server, I mean a box, you know the beige type with lots of electronic things inside ;). Seriously, I don't know if it's a pizza box or what, just that's not a "real" server with a RAID controler. I thought about doing soft RAID, but: 1) The hard disks don't have the same size, 2) I don't know if you can do RAID0 on soft (but would have go for RAID1 anyway) 3) That's not something I'd feel confortable doing remotely at all, 4) I'm not an "hardware guy" at all. Last time I ran fdisk, I managed to cut myself ;) For all of these reasons, I don't consider RAID0 as an option. I read than creating two swap partition and put them on each disk makes the PC happier. Beside that, I don't know how to split the load between the two disks. hda = apache files hdc=mysql ones ? hda = design/templates hdc = var/cache ? Have you tried ? Does it change anything ? X+ http://www.sydesy.com
Łukasz Serwatka	Tuesday 24 January 2006 5:27:25 am Remember that between communication of two disks is always controller which is not that fast as we want ;) I don't think so that splitting content between two disks will give you additional performance, I can't see difference for now ;) I always keep Apache files and Database Server files on the same partition so disk header don't have to jump between partitions. The most important is to have separated swap and system file partition from data partition which is always more fragmented due to heavily usage. Now every good motherboard has built-in RAID controller, SATA or ATA, with 0 or 1 or 0+1 support. Just choose the fastest disk and keep data on it. Personal website -> http://serwatka.net Blog (about eZ Publish) -> http://serwatka.net/blog
Gabriel Ambuehl	Tuesday 24 January 2006 7:35:37 am Any decent RAID1 setup should give you much improved read times while usually having a slight impact on write speed. Anything else is probably not worth the trouble for most cases or as in case of RAID0, downright stupid. I'd venture to guess that ezpublish will likely NOT be disk speed limited very highly as you will usually be able to fit quite a lot of stuff into disk cache if you have any sane amount of RAM in a box. And remember: those on board "RAID" controllers are really just software RAID (the driver does all the work) plus a BIOS. Visit http://triligon.org
Paul Borgermans	Tuesday 24 January 2006 8:59:57 am Don't forget the file-system as well. FYI, I use typically ReiserFS on top of 2 raid arrays: one array raid 1 for OS and /var, raid 5 for a /srv where all ez publish and related stuff resides. In my experience, the bus speed to RAM and CPU's are of utmost importance and also go with enough ram. Our top server now is a Dell Poweredge 2800, with dual 3.8Ghz Xeon 64 bit CPU (2MB L2 cache), 15000rpm SCSI disks with hardware raid controller, 4GB RAM and with 64 bit versions of kernel, php, .... It's fast :-)) --paul eZ Publish, eZ Find, Solr expert consulting and training http://twitter.com/paulborgermans
Gabriel Ambuehl	Tuesday 24 January 2006 9:04:58 am Personally, I had reiserfs destroy 3 different filesystems in my own box so these days, I advise to use anything but reiserfs (XFS and ext3 are both decent). Visit http://triligon.org
Paul Borgermans	Tuesday 24 January 2006 10:27:44 am Hi Gabriel I've read horror stories as well, but never encountered a problem in the last 6 years I started using Linux (SuSE) in favor of Solaris (including disk crashes, power outages, raid controller failures, upgrades of kernel/reiserfs on live, busy servers). I may be just lucky of course ;-) --paul eZ Publish, eZ Find, Solr expert consulting and training http://twitter.com/paulborgermans