[DRBD-user] Large drbd devices vs vmalloc workarounds

Leroy van Logchem leroy.vanlogchem at wldelft.nl
Sun Apr 24 23:32:22 CEST 2005

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hi,

I have two drbd devices working fine. Each 1.4 tB running on rhes4
2.6.9-5.0.5.ELsmp using drbd-0.7.10. Adding a thirth device hangs the
module:

/allocation failed: out of vmalloc space

/After some research I changed the grub and kernel config like this:

<grub.conf>
title Red Hat Enterprise Linux ES (2.6.9-5.0.5.ELsmp)
        root (hd0,0)
        uppermem 524288
        kernel /boot/vmlinuz-2.6.9-5.0.5.ELsmp ro root=LABEL=/ rhgb 
quiet vmalloc=192m
        initrd /boot/initrd-2.6.9-5.0.5.ELsmp.img

The servers have 1GB memory but grub is told to load the initrd *past* 
the vmalloc by the use of uppermem (512 * 1024).
After this the vmalloc=192m option doesnt hangup the loader anymore and 
/proc/meminfo VmallocTotal increased from 106488 kB to 172024 kB.

Q: What are the memory requirements for this configuration?
Q: Will the memory footprint increase during production use?
Off-topic Q: Any tips for production setups using multiple tB's (ext3) 
exporting nfs/smb only using HB+Mon? Failovers are <15 sec. and 
drbd'fied /var/lib/nfs gives HA nfs v3 nicely.

-- Leroy





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