On Mon 21 Feb 05, 11:14 AM, Rick Moen <[EMAIL PROTECTED]> said: > Quoting Peter Jay Salzman ([EMAIL PROTECTED]): > > > 1. Having multiple swaps per disk is of almost no benefit at all. > > So, a client of mine builds Linux servers, and provides a custom RHEL > 3.0 build image for one particular customer that buys a lot of 4 GB RAM > dual Opteron systems with dual 73GB SCSI drives. Customer management, > for reasons that passeth understanding, insisted they wanted 32GB of > swap space on each node,
Jumping Jehosephat!!! > and moreover wanted all of it in a single partition on the boot drive. core dumped. > nSuch systems were duly delivered, but > customer soon reported that the systems were hanging hard while in > production use. > > Extensive tests followed using the Cerberus Test Control Suite (CTCS), > which stress-tests Linux boxes using a number of simultaneous software > processes including iterative kernel compiles. With a single 32GB swap > partition, CTCS induced a system hang in 1 day. With a pair of 16GB > swap partitions, CTCS hung the box in 2 days. With four 8 GB swap > partitions, five days. And thus up to the ideal configuration, using as > many 2 GB swap partitions as the limits on SCSI device numbers > permitted, in which, as far as we could tell, CTCS ran forever. The > customer's load image was duly modified, and the cause has been > presumptively attributed to hitting a bug in the RHEL 3.0 kernel's VM code. > > (Yes, there was indeed no rational reason why customer needed to deploy > all that swap in the first place. But that's not the point I was > making.) But does anyone even KNOW what caused the hang? Maybe it was the fact that fdisk was run on Wednesday without the hardware clock reading 3:30 while Mars and Jupiter were in alignment. That's the thing with bugs -- you really don't know anything unless you study the bug. Other than a story of a poorly understood case where multiple swaps per disk seemed to surpress the expression of a VM bug, can you describe what benefit multiple swaps per disk give? Maybe someone, somewhere can tell a story where multiple swaps per disk crashed a system due to a filesystem bug. ;) Pete -- Save Star Trek Enterprise from extinction: http://www.saveenterprise.com GPG Fingerprint: B9F1 6CF3 47C4 7CD8 D33E 70A9 A3B9 1945 67EA 951D _______________________________________________ vox-tech mailing list [email protected] http://lists.lugod.org/mailman/listinfo/vox-tech
