SUN SPARCstorage Tricks
SUN SPARCstorage Array Tricks
We're doing some cool things with our arrays (when they're not busy
corrupting our data :-) (See a survey I conducted
and the post-survey update to find out some
of the problems and concerns we've had with the SSA's.) Aside from the
filesystem corruption problems, we've been trying to make good use of
some of the niftier features of the SSA's, especially the dual-porting
capability.
We're using our arrays for
- user homedirectories and institutional web data
- news slave spools
We have taken some measures to optimize our arrays' performance:
- We have shied away from RAID5 in favor of RAID0+1 -- it's worth the
extra money to avoid the performance hit and hassle of RAID5.
- We tune the UFS filesystems residing on the arrays to work well with
the stripe sizes
- We have turned on fast_writes. Note that if you are running SDS (we
run VxVM) some patches are required if you want to use fast_writes.
Probably the niftiest thing we're trying to do with our arrays is to use
the dual-porting capability to try to provide stable backups.
- Each array has a connection to the NFS server host and a dedicated
host we call the Backup host, which has the tape drives attached.
- We provide a number of "slush" disks (for 15-18 disks of data, we
have 6 "slush" disks) for backing up the chunks of the data.
- When it is time to do a backup, we take a Veritas snapshot of the
filesystem in question using the slush disks (e.g., a snapshot of a
volume spanning a "6-pack" of disks will be placed on the backup 6-pack).
- Through smoke and mirrors (read: lots of hairy perl scripts) we tear
off the backup 6-pack, put it in its own disk group, deport the disk
group, and import the disk group on the Backup host.
- The Backup host is now free to mount the snapshot volume and back it
up to its local tape drives.
This scheme is complicated but it allows us to
- Run backups during the day. The snapshot does pose some performance
impact, but you can specify a "niceness" factor (sleeps between copies)
to alleviate some of the load.
- Separate the ufsdump and tape-writing overhead from the NFS service.
- Most importantly, have "safer" backups -- files are not changing on
the stable, readonly snapshot of the production volume.
Last updated: Thu Jun 20 23:08:45 1996
Back to marg's SUN SPARCstorage Array Page