On Dec 27, 2013, at 11:01 AM, Josh Fisher wrote:
On 12/20/2013 7:10 PM, Levie, Jim wrote:
I have a group of three CentoOS 5.10 boxes and client backups are, well, slow.
The hardware specs are that the systems are all Dell R710's (dual quad
processors w/24GB of memory). The Bacula server/storage node has a Dell LT04
Powervault 124T and is an authentication only server (LDAP) for a small (~20
node) network. Each of the clients is a pure file server with dual bonded 1Gps
links to a CISO switch. One with 3TB and the other with 3TB internal and 6TB in
an external hardware RAID box. The total to be backed up is about 11TB.
Compression is not used, but spooling into a 5GB space with 10k SAS drives in
RAID 0 is used. The overall rate on the sever/storage node is only about
10-12Mps and that on either of the clients is only about 9-10Mps. It takes
5-6days to get a full backup. It would seem like I should be getting better
than that.
Your spool space is probably too small. It does not work like a
reader/writer ring buffer. When the spool fills, the clients must wait
while the storage daemon de-spools to tape. Also, you should be setting
the spool size in the config file, rather than letting Bacula detect the
disk full error to trigger de-spooling. A 5 GB spool size means the
clients will stall more than 2,000 times while writing the 11 TB.
If the spool space cannot be larger, then I suggest not using data
spooling, but rather attribute-only spooling. Your clients are likely
fast enough to keep the Powervault busy without data spooling. In
general, if your clients are fast enough to keep the tape drive busy,
then there is not much to be gained by data spooling.
Attribute spooling, though, is critical, else all the DB random i/o will
slow down backups. It is also a good idea to have the DB on a different
partition than the Bacula work directory (where the attribute spool file
is located) in order to speed up de-spooling of attributes.
I can easily make the spool space larger (by a lot) and the size of the spool
area is set in the config files. But I'm not so sure that will significantly
increase the overall backup rate. The fill time to the 5gb point on the spool
yields a data rate only slightly greater than the overall rate.
Spool Data is set to yes, which should automatically turn attribute spooling
on. The DB and both spools are on separate partitions which in turn are on
separate disks.
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