Hi all,
Please note that NetApp themselves have something which is called 'NetApp Usable Capacity Calculator.xls' which is available to partners.
You might want to speak to your NetApp representative and save yourself a lot of calculation headaches ;-).
Cheers, Roger
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of van Teylingen, Geert Sent: di 01 aug 06 0:33 To: Bokkelkamp, Ernst; margesimpson@hushmail.com; toasters@mathworks.com Subject: RE: Storage space overheads!
Hi,
In this context it might be good to read Dave Hitz' Blog entry on RAID-DP and "overhead"...: http://blogs.netapp.com/dave/TechTalk/?permalink=Why-Double-Protecting-R AID-RAID-DP-Doesnt-Waste-Extra-Disk-Space.html
Enjoy!
Met vriendelijke groet / With kind regards, ___________________________________________
Geert van Teylingen System Engineer Network Appliance B.V.
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-----Original Message----- From: Bokkelkamp, Ernst [mailto:ernst.bokkelkamp@siemens.com] Sent: Monday, July 31, 2006 08:30 To: margesimpson@hushmail.com; toasters@mathworks.com Subject: RE: Storage space overheads!
"I wish NetApp had Raid5, this could have eliminated some issues like using 2 dual-parity drives."
Why ?
Somehow I get the impression, looking at the last few messages, that the majority does not understand raid_dp and the differences to raid_4. For practical purposes raid5 + some filesystem is "like" raid4 + wafl, particulary when you compare the data : parity disk ratio. Comparing raid4 to raid_dp you should notice that raid_dp provides a better protection with equal overhead when used on large volumes/aggregates. Large aggregates use the same number of parity disks but the raid_dp parity disks protect twice as many data disks compared to raid4. Sometimes the cost of one drive can be justified to provide additional
protection on small volumes/aggregates, if not than you can always use raid4 instead.
Btw: there is an interesting document on WAFL in the knowledgebase - it is definitely worthwile to understand the principles behind WAFL to
understand the benefits of raid4 and raid_dp.
Ernie
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of margesimpson@hushmail.com Sent: Montag, 31. Juli 2006 02:19 To: toasters@mathworks.com Subject: RE: Storage space overheads!
Hi all, Thank you very much. It seems out of 100GB, what usable space I can have is 55GB (55%). I feel yauk! But it seems at this point of time, its the only solution. I wish NetApp had Raid5, this could have eliminated some issues like using 2 dual-parity drives. Thank you again for your responses about SATA and FC disks.
Cheers, Marge.
On Fri, 28 Jul 2006 19:19:08 +1000 "Holland, William L" HollandWL@state.gov wrote:
We have a R200 which has 168 ATA drives. I expected a high failure rate on these as ATA drives are not rated for continuous
duty. I have
been surprised, and pleased, that failure rate has been very low - perhaps 3 drives in a year. Not sure about the SATA. The way I am moving is to use (S)ATA for my NAS (user shares) and FC drives for hosting my iSCSI LUNs. Databases need the higher performance of FC, simple file shares do not.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner- toasters@mathworks.com] On Behalf Of margesimpson@hushmail.com Sent: Thursday, July 27, 2006 10:00 PM To: toasters@mathworks.com Subject: RE: Storage space overheads!
Hi Glenn D, Glenn W, Andrew, Michael, Holland and Holland,
Thank you
all for your feeback.
To summarize, the following is true (i.e., about storage sacrifice):
- Disk are right sized (realigning size in blocks from different
vendors...eg., for 72GB we get 68GB) before using by NetApp.
- dual parity (2 disks on RG of 16 => 14D+2P)
- spare disk/s
- WAFL & RAID overhead (~ 5%).
- aggr reserve 5% default
- vol snapshot reserve 20% default
- for LUNs: 50% for base snapshot + extra space 20% of remaining
data
space
- user data should always be below 90% to avoid performance
bottleneck
and defrag issues.
That's sounds bad to me, but if you all feel to be true then
its must
be a solution.
How about putting SATA disks on the primary filers to save costs? Whats are the problems in replacing FC disks with SATA? Whats record about SATA disks, I heard they are terrible? (Failure
rates is abnormal)
Thanks again for feedback. Marge.
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Sels Roger