Don,
Are you getting more MB/sec when dumping to null, or when reading from CIFS/NFS? To answer your first assesment - it´s a theoretical question, I would assume that it´s not necessarily correct. Let´s say you would have configured 2 separate volumes instead of one large aggregate - each one of them would have less disks so you would not necessarily gain faster performance....
For your loops question - look at your 80MB/sec result - you are far away from loops being your bottleneck. I have seen many filers in the last few years and cannot remember cases where loops were maxing out.
Eyal. http://filers.blogspot.com http://stupidstorage.blogspot.com
On 10/11/06, Glascock, Donald glascock.donald@mayo.edu wrote:
Hi, again, Toaster folks --
Thanks, Darren and Eyal, for taking the time to reply.
From your observations, it sounds like our choice for "ultimate flexibility" with regard to volume sizing by creating only one aggregate on our FAS960 was also a choice away from fast backup speed for simultaneous dumps. Is that a fair assessment?
Is anyone successfully running full simultaneous dumps to separate tape drives (utilizing separate FC paths from the filer to the fabric, and from the fabric to the drives) from two or more aggregates on one filer (whatever model you may have) at rated speed?
Eyal writes:
[...] adding shelves would actually help you achieve faster dumps, not slower.
Would the shelves be best added to our existing two loops, or would we do better to buy yet another HBA for them? Intuitively, a busier loop doesn't sound like an optimal configuration; on the other hand, we've been told that our FAS960's existing five HBAs have pretty much maxed "all of the busses" in our FAS960.
While I'm trying to keep this discussion mostly about the system architecture and what we should be able to expect for backup performance, I can tell you that we're running DOT 7.0.4 while waiting for a few more folks to run 7.2 for a while, and we are getting ~80 MB/sec when dumping volumes individually. We dump fulls once per month, and we can split up the monthly dump process across a few nights if we absolutely have to. When we dump two volumes simultaneously, the write speeds of the drives hover around 40-50 MB/sec, and when we write three, they hover around 30-40 MB/sec.
Thanks again for your time & have a great day!
Don Glascock
-- Donald S. Glascock Mailstop RO-SN-2-SPPDG Special Purpose Processor Development Group Mayo Foundation 4001 41st Street NW Rochester, MN 55901 Glascock.Donald@Mayo.EDU +1.507.538.5467 +1.507.284.9171 (fax) http://www.mayo.edu/sppdg/ "No matter where you go, there you are."
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Glascock, Donald Sent: Tuesday, October 10, 2006 3:24 PM To: toasters@mathworks.com Subject: FAS960: backup speed vs simultaneous dumps...?
Hi, Toaster folks --
We're a small research group on our third Filer, which is a single FAS960 with five shelves on two cross-connected 2-Gb loops. We trigger flexVolume-level dumps of our one aggregate directly to 2-Gb-fibre-connected LTO-3 drives.
When we dump two volumes simultaneously to two tape drives, the time taken to dump each volume increases by a third to a half again, compared to dumping each volume independently. For example, a stand-alone dump may take two hours, but if another dump of another volume to another drive is run simultaneously, then that two-hour dump becomes a three-hour dump. Adding a third simultaneous dump to a third drive causes an even greater increase in dump times.
For diagnostic purposes, I've launched a conventional dump of one volume triggered via NDMP our backup software, waited for the dump to reach Phase-IV (the writing-data phase), and launched from the FAS960's console a dump of another volume to the FAS960's null device. Soon after this second dump starts, the write speed on the tape drive associated with the first dump falls off by quite a bit. This write speed picks up instantly when I kill the second dump. Since the second dump was only in Phase-I (inspecting files, but not writing them), and since this second dump was to the local null device anyway, I'm led to think that the performance issues lie somewhere within the Filer's head and Disk I/O subsystem.
With one-at-a-time backups of our volumes, our full backup window is about eight hours (for about two terabytes). We were planning to buy two more shelves in early 2007.
Should I expect a FAS960 to handle two or three simultaneous full dumps without a significant loss in dump speed? Are you getting nearly-linear performance out of your simultaneous dumps?
Thanks for your time & have a great day!
Don Glascock
-- Donald S. Glascock Mailstop RO-SN-2-SPPDG Special Purpose Processor Development Group Mayo Foundation 4001 41st Street NW Rochester, MN 55901 Glascock.Donald@Mayo.EDU +1.507.538.5467 +1.507.284.9171 (fax) http://www.mayo.edu/sppdg/ "No matter where you go, there you are."