Sun's Online:DiskSuite for News spool - configuration?

2007-12-25 8:47:00

About a week ago, I wrote asking about the above subject - since I think

I got some good advice, and a couple of metoo's, here is a short summary.

Basically, the issue was how to configure ODS to get the most performace

improvement out of using two disks instead of one for spool.

Everybody agreed that using striping with a small interlace was the

absolute worst thing to do - just about every article access would have

to request I/O from both disks, with little or no benefit (the only case

were it makes sense to have an interlace smaller than typical file sizes

is with single processes seqentially accessing very large files - i.e.

the exact opposite of News).

As for striping with a large interlace (i.e. cylinder size) vs

concatenation, opinions varied a bit. Several respondents agreed with my

suspicion that it wouldn't really matter much one way or the other, but

Jerry Aguirre pointed out a couple of possible advantages with striping:

Since the FFS tries to keep directories (=newsgroups) "together", you

would tend to get all of a given newsgroup on one of the disks with

concatenation, whereas it would be more likely to be split between them

with striping - this means that with concatenation,

- you *could* end up with unbalanced load, e.g. if one of the disks

happened to get a higher proportion of high traffic/readership groups

- expiration (i.e. INN's fastrm) would typically beat at one disk at a

time, rather than splitting the load between them.

Kean Stump had actually tried both striping and concatenation for the

News spool, and gotten much better performance with concatenation. He

had used a small (4k) interlace though, and if I understood right the

change to concatenation may have coincided with starting to use separate

controllers, which will of course be a benefit in any case.

I will go with striping, using the default cylinder-size interlace.

Thanks to:

len@contec.COM (Leonard Mills)

--Per Hedeland

...uunet!erix.ericsson.se!per

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