On Sat, Jun 23, 2001 at 09:34:59AM +0200, Russell Coker wrote: > On Saturday 23 June 2001 04:10, Nick Jennings wrote: > > > > The main performance benefit to having directories reside on their own > > partition relates to file write/read access. It's very important to > > have var on it's own seperate partition, specifically because it's > > probably the most actively written to directory. > > OK. If you have a single physical hard drive or RAID array, the how will > having /var on a separate partition give any benefit? Disk access still > goes to the same hardware and is still limited by head seek times and > rotational delays of the hardware. Having two seeks on the same > partition or two seeks on separate partitions should not perform any > differently.
I guess I was going by the same logic of the swap partition, having your partitions ordered by most usage. I also added into this having your system partitioned into logical segments to increase maintnence ease. > > However if you have a single large partition then when you are writing > data the FS drivers can optimise things. I always thought that this was a performance hit, I know I've read it in places before, but I can't seem to find them as I look right now. > > > Another little performance gain is the order in which you partition > > your disks (the closer to the 0'th cylinder the faster the access time. > > This depends on the type of device. This is a general rule that doesn't > always apply. But when it does apply it's not so small. 50% extra > performance at the start of the disk is not uncommon. > > AFAIK I'm the only person to publish a benchmark program to measure > this... > > > For instance, this is the order in which I usually go about > > partitioning my drive (note: it varies depending on it i'm setting up a > > workstation or a server, but they are similar). > > > > <swap> size: totalmem*2 (64mb = 128mb partition) > > / > > /tmp > > <extended> > > /usr > > /var > > /home > > Swap is often the most used partition. Root is probably the least. /tmp > and /home are both candidates for the most used partition. Having things > separate like this means that in many common usage situations you'll have > the heads seeking across the entire disk all the time. Having a single > partition could increase performance... Good point, I've put / at the beginning just out of habit, put I think that, especially on a server, /var is much more used than home is. and /usr is where every application is executed from, that's gotta count for something. I would venture to say that, on a server thats not offering lots of shell accounts, /home is the least used. > > > If I run out of room on /var/www or /var/cvs or something, I can stick > > another disk in and mount that in its place instead. I used to get > > worried about wasted space, but if you just over estimate a bit, you > > should be fine with most of the partitions that don't grow (like /, > > /tmp, /usr). And you just give the most space the the ones that can > > grow. Now I find a nice partitioning scheme to be much more manageable > > and the performance is very noticable. > > If sticking another disk in is so easy then why not just install lots of > disks in a RAID array from the start? That'll get the best performance... > Well because a hardware RAID is more expensive than a scsi or ide drive. Also because I'm thinking of one disk, with the possible expansion onto another one, or two. not starting out with several. -- Nick Jennings
