Re: RAID5 slowness (how to fix?)

On Mon, 24 Apr 2006 13:29:52 -0400, John-Paul Stewart wrote:

11 hours may be perfectly normal. Describe the RAID array (number of
disks, size of each disk, are they IDE/SATA/SCSI). What backup device
are you using (e.g., tape, another part of the same array, USB hard disk)?

Have you run any simple benchmarks on the array? Even 'hdparm -tT
/dev/md0' (or whatever the RAID device is) would be helpful.

OK ..

So, I have 3 disks in the raid array. They are each 300GB IDE drives
(parallel ATA) from Western Digital (same make and model). We are
currently backing up over the network to another machine (which, I
believe, is first stored to the hard drive, and then later recorded to
tape).

hdparm -tT yields the following:

# hdparm -tT /dev/md0

/dev/md0:
Timing buffer-cache reads: 1764 MB in 2.00 seconds = 882.00 MB/sec
Timing buffered disk reads: 18 MB in 3.23 seconds = 5.57 MB/sec

We are currently backing up about 53GB of data.

The IDE configuration is:

Primary Master: IDE HD (not part of RAID) containing OS
Primary Slave: RAID
Secondary Master: RAID
Secondary Slave: RAID

.

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