Everyone, We just had a pretty bad crash on one of production boxes and the ext2 filesystem on the data partition of our box had some major filesystem corruption. Needless to say, I am now looking into converting the filesystem to ext3 and I have some questions regarding ext3 and Linux software RAID. I have read that previously there were some issues running ext3 on a software raid device (/dev/mdN), but that most of those issues are resolved by running kernel 2.4.x. Currently we are running 2.4.16 on our producton system and we have a rather complicated hardware/software RAID configuration on the box. Now for the details of my system. See http://w3.one.net/~djflux/graphics/raiddiag.png for a graphic of our RAID configuration. We have 2 Dell PowerVault 220S filled with 15K 18GB SCSI drives. Each drive in PowerVault 1 is hardware mirrored to the corresponding drive in PowerVault 2. I then use Linux software RAID0 to create a stripe across these 12 drives (/dev/md0). This setup is kind of convoluted due to hardware restraints (a Dell PERC3QC RAID card can only span [RAID10] 8 drives and we wanted 12). Internal to the box I have 7 (10K 36GB) SCSI disks and a hardware stripe (RAID0, /dev/sdb1). I then use Linux software RAID1 to mirror this drive with the software RAID0 creating /dev/md1. I know I'm only using a portion of the full space on /dev/sdb1, but it is hoped to use it all at some later date. There is an ext2 filesystem on /dev/md1 that is used for the Informix/IBM database called UniVerse. The reason for this RAID configuration is to have a static copy of data to be used for backups. I suspend database operations long enough to use mdctl to fail and remove /dev/sdb1 out of /dev/md1. I can then backup the static database data knowing that it is a valid point-in-time snapshot of my database. Tar is used to archive this drive to tape and then it is hotadded back in to /dev/md1 for resync after the tar archive completes. The box is a Dell PowerEdge 6400 with 4 700MHz Xeon, and 8GB of RAM. The box hosts approximately 450 users during the average business day. The database is currently about 70GB and the partition on /dev/md1 is about 200GB. The database has a few large files that the majority of system users access very frequently, mostly for reads, but also for updates. We want the highest level of integrity for our data, but do not want to impact the interactivity of the machine very much. Current system load averages range from 0.33 to 3.50 and occasionally spiking higher. Now that you know the basics of my system and our ideal requirements, I have a few questions: - Is it wise to convert the filesystem on /dev/md1 to ext3? - Have the issues with ext3 on Linux RAID been resolved? - Will the failing and resyncing of /dev/md1 happening on a daily basis cause problems with the journalling? - Do you think the filesystem would be stable enough for 18x7 availability? - What kind of overhead is involved after the filesystem is ext3? - What journalling mode is suggested for this type of application/system configuration? - What size journal would be appropriate give data=ordered vs. data=journal? - And any other suggestions/insights/comments. Below is our /etc/raidtab. Let me know if you need any more information. Thank you in advance for all your assistance. Regards, Andrew Rechenberg Network Team, Sherman Financial Group arechenberg@shermanfinancialgroup.com raiddev /dev/md0 raid-level 0 persistent-superblock 1 chunk-size 64 nr-raid-disks 12 nr-spare-disks 0 device /dev/sdc1 raid-disk 0 device /dev/sdd1 raid-disk 1 device /dev/sde1 raid-disk 2 device /dev/sdf1 raid-disk 3 device /dev/sdg1 raid-disk 4 device /dev/sdh1 raid-disk 5 device /dev/sdi1 raid-disk 6 device /dev/sdj1 raid-disk 7 device /dev/sdk1 raid-disk 8 device /dev/sdl1 raid-disk 9 device /dev/sdm1 raid-disk 10 device /dev/sdn1 raid-disk 11 raiddev /dev/md1 raid-level 1 persistent-superblock 1 chunk-size 64 nr-raid-disks 2 nr-spare-disks 0 device /dev/md0 raid-disk 0 device /dev/sdb1 raid-disk 1
