large filesystem & fileserver architecture issues.

Nicholas Henke henken at
Mon Aug 4 15:31:22 EDT 2003

Hey all -- here is our situation.

We currently have several clusters that are configured with either IBM
x342 or Dell 2650 serves with their respective vendors SCSI RAID arrays
hanging off of them. Each server + array is good for around 600GB after
RAID 5 and formatting. The IBM's have the added ability to do a RAID 50
of multiple arrays ( which seems to work & perform quite nicely ). Each
of the servers then exports the filesystem via NFS, and is mounted on
the nodes. The clusters range from 24 to 128 nodes. For backups we
maintain an offline server + array that we use to rsync the data
nightly, then use our amanda server  and tape robot to backup. We use an
offline sync, as we need a level 0 dump every 2 weeks, and doing a level
0 dump of 600GB just trashes the performance on a live server. As we are
a .edu and all of the clusters were purchased by the individual groups,
the options we can explore have to be very cost efficient for hardware,
and free for software.

Now for the problem...
A couple of our clusters are using the available filespace quite
rapidly, and we are looking to add space. The most cost efficient
approach we have found is to buy a IDE RAID box, like those available
from RaidZone or PogoLinux. This allows us to use the cheap IDE systems
as the offline sync, and use the scsi systems as online servers.

And the questions:

1) Is there a better way to backup the systems without the need for an
offline sync? 

2) Does anyone have experience doing RAID 50 with Dell hardware? How bad
does it bite ?

3) Are there any recommended IDE RAID systems? We are not looking for
super stellar performance, just a solid system that does it's job as an
offline sync for backups.
Nicholas Henke
Penguin Herder & Linux Cluster System Programmer
Liniac Project - Univ. of Pennsylvania

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