kts@quintro.uucp (Kenneth T. Smelcer) (02/09/90)
Our site is looking at adding a large disk server (~700M) to our network,
and we've been wondering what the critical performance parameters are
for a network disk server (other than drive speed).
Does CPU performance make a large difference in throughput?
Will the OS take advantage of more memory (Ex. 8M vs 16M) for a
major performance win?
The three different configurations we are considering are:
1. DSP 3500 - 8 Meg RAM - 697 Meg disk
2. DN 2500 - 16 Meg RAM - 663 Meg SCSI disk
3. DN 3000 - 8 Meg RAM - 697 Meg disk
Would the 3000 be much slower than the 3500 (as a disk server)?
(The only reason we're considering this is because we could add the disk
to an existing 3000 and use the remaining $$$ to buy another DN2500).
Any Opinions?
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Ken Smelcer Glenayre Corp. quintro!kts@lll-winken
Quincy, IL tiamat!quintro!kts@uunetdbfunk@ICAEN.UIOWA.EDU (David B Funk) (02/10/90)
In posting <1990Feb8.230843.18026@quintro.uucp> Ken Smelcer says: > Our site is looking at adding a large disk server (~700M) to our network, >and we've been wondering what the critical performance parameters are >for a network disk server (other than drive speed). > > Does CPU performance make a large difference in throughput? > > Will the OS take advantage of more memory (Ex. 8M vs 16M) for a > major performance win? > >The three different configurations we are considering are: > > 1. DSP 3500 - 8 Meg RAM - 697 Meg disk > > 2. DN 2500 - 16 Meg RAM - 663 Meg SCSI disk > > 3. DN 3000 - 8 Meg RAM - 697 Meg disk I'll take the easy one first. (3.) DN300 + 697 Meg disk = NoGo. You can't put a 697 meg in a DN3000, the Omti controller won't handle it. You can only put a 697 Meg disk in a machine that has the new Western Digital WD7000 disk/SCSI controller. (And in a DN10k :-). The best that you can do with a DN3000 is a single 348 Mbyte disk, as it won't take a WD controller. (1.) DN3500 + 8 meg RAM + 697 Meg disk This is a reasonable combination. This requires the DN3500 to have a WD controller (early DN3500s had the Omti, only machines shipped in the last year came with the WD). Since the WD controller can handle 2 disks, you can add a second drive as your needs (and budget) expand. (Note that both disks must be the same size, you can't add a 697 to a machine that already has a 348.) If you really need more elbow room, you can add a second WD controller & pair of 697 disks to a DN3500, giving you a max of 2.6 Gig of usable disk space. We are using this combination as a replacement for our old DSP90s. (I won't miss those biannual MSD500 crashes %=} (2) DN2500 + 16 Meg RAM + 663 Meg SCSI disk. I havn't seen the 663 Meg disk for the DN2500 so I don't know how well it works. The 200 Meg drives work OK so I would expect that the 663 would too. It might be a reasonable file server, particularly with the extra RAM. Yes, the OS will make use of as much RAM as you can give it. It will buffer active pages in RAM and will be a performance win (as well as reduce wear & tear on the disk). CPU speed is not as critical a factor as I/O bandwidth. For example, a DN4500 will give about the same performance as a DN3500 when used as a file server as they both have the same I/O system (assuming all other factors equal). The DSP90 was about twice as fast as the DSP160 because it had a better I/O bus system for the MSD500 disks. The DN3000 is about half the I/O speed of a DN4000. This is due to the DN3000 lack of an I/O page mapper as well as the slower I/O bus clock & CPU clock rates. I feel that the critical performance parameters for a file server are: disk speed, I/O rate, & RAM size, with CPU speed being a distinct 4'th place consideration. Dave Funk