Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread Yeb Havinga
On 2011-07-18 03:43, Andy wrote: Hi, Is BBU still needed with SSD? SSD has its own cache. And in certain models such as Intel 320 that cache is backed by capacitors. So in a sense that cache acts as a BBU that's backed by capacitors instead of batteries. In this case is BBU still needed? If

[PERFORM] cpu comparison

2011-07-18 Thread M. D.
I have 2 small servers, one a fairly new server with a x3450 (4-core with HT) cpu running at 2.67GHz and an older E5335 (4-core) cpu running at 2GHz. I have been quite surprised how the E5335 compares very closely to the x3450, but maybe I have tested it wrongly. here's the CPUINFO: processo

Re: [PERFORM] cpu comparison

2011-07-18 Thread k...@rice.edu
On Mon, Jul 18, 2011 at 01:48:20PM -0600, M. D. wrote: > I have 2 small servers, one a fairly new server with a x3450 (4-core > with HT) cpu running at 2.67GHz and an older E5335 (4-core) cpu > running at 2GHz. > > I have been quite surprised how the E5335 compares very closely to > the x3450, but

Re: [PERFORM] cpu comparison

2011-07-18 Thread Tomas Vondra
Dne 18.7.2011 22:11, k...@rice.edu napsal(a): >> > In my testing I have a 32bit CentOS on the x3450, but a 64bit CentOS >> > on the E5335. Can this make such a bit difference or should the >> > perform fairly close to the same speed? Both servers have 8GB of >> > RAM, and the database I tested wi

Re: [PERFORM] cpu comparison

2011-07-18 Thread Josh Berkus
On 7/18/11 12:48 PM, M. D. wrote: > I have 2 small servers, one a fairly new server with a x3450 (4-core > with HT) cpu running at 2.67GHz and an older E5335 (4-core) cpu running > at 2GHz. > > I have been quite surprised how the E5335 compares very closely to the > x3450, but maybe I have tested

Re: [PERFORM] cpu comparison

2011-07-18 Thread k...@rice.edu
On Mon, Jul 18, 2011 at 11:56:40PM +0200, Tomas Vondra wrote: > Dne 18.7.2011 22:11, k...@rice.edu napsal(a): > >> > In my testing I have a 32bit CentOS on the x3450, but a 64bit CentOS > >> > on the E5335. Can this make such a bit difference or should the > >> > perform fairly close to the same s

Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread David Rees
On Sun, Jul 17, 2011 at 7:30 PM, Craig Ringer wrote: > On 18/07/2011 9:43 AM, Andy wrote: >> Is BBU still needed with SSD? > > You *need* an SSD with a supercapacitor or on-board battery backup for its > cache. Otherwise you *will* lose data. > > Consumer SSDs are like a hard disk attached to a RA

Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread Greg Smith
Andy wrote: SSD has its own cache. And in certain models such as Intel 320 that cache is backed by capacitors. So in a sense that cache acts as a BBU that's backed by capacitors instead of batteries. Tests I did on the 320 series says it works fine: http://archives.postgresql.org/message-i

Re: [PERFORM] cpu comparison

2011-07-18 Thread Greg Smith
M. D. wrote: I'm a bit surprised as the x3450 has DDR3, while the E5335 has DDR2, and of course because of the cycle speed difference alone I would think the X3450 should beat the E5335. Try comparing them with stream-scaling to see what happens: https://github.com/gregs1104/stream-scaling Y

Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread Andy
--- On Mon, 7/18/11, David Rees wrote: > >> In this case is BBU still needed? If I put 2 SSD > in software RAID 1, would > >> that be any slower than 2 SSD in HW RAID 1 with > BBU? What are the pros and > >> cons? > > What will perform better will vary greatly depending on the > exact > SSDs,

Re: [PERFORM] cpu comparison

2011-07-18 Thread Scott Marlowe
On Mon, Jul 18, 2011 at 6:47 PM, Greg Smith wrote: > M. D. wrote: >> >> I'm a bit surprised as the x3450 has DDR3, while the E5335 has DDR2, and >> of course because of the cycle speed difference alone I would think the >> X3450 should beat the E5335. > > Try comparing them with stream-scaling to

Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread Bruce Momjian
Andy wrote: > > > --- On Mon, 7/18/11, David Rees wrote: > > > >> In this case is BBU still needed? If I put 2 SSD > > in software RAID 1, would > > >> that be any slower than 2 SSD in HW RAID 1 with > > BBU? What are the pros and > > >> cons? > > > > What will perform better will vary greatly

Re: [PERFORM] cpu comparison

2011-07-18 Thread M. D.
On 07/18/2011 03:56 PM, Tomas Vondra wrote: Dne 18.7.2011 22:11,k...@rice.edu napsal(a): In my testing I have a 32bit CentOS on the x3450, but a 64bit CentOS on the E5335. Can this make such a bit difference or should the perform fairly close to the same speed? Both servers have 8GB of RAM, a

Re: [PERFORM] BBU still needed with SSD?

2011-07-18 Thread Andy
> > I'm not comparing SSD in SW RAID with rotating disks > in HW RAID with > > BBU though. I'm just comparing SSDs with or without > BBU. I'm going to > > get a couple of Intel 320s, just want to know if BBU > makes sense for > > them. > > Yes, it certainly does, even if you have a RAID BBU. "ev

Re: [PERFORM] cpu comparison

2011-07-18 Thread Samuel Gendler
I'm just top posting this because this whole thread needs a reset before it goes any farther. Start with a real description of these hosts - Number and types of disks, filesystem configs, processors, memory, OS, etc. If your db is small enough to fit into RAM, please show us the db config you are