gvinum raid5 vs. ZFS raidz
bennett at sdf.org
Mon Sep 1 22:19:48 UTC 2014
Paul Kraus <paul at kraus-haus.org> wrote:
> On Aug 31, 2014, at 3:49, Scott Bennett <bennett at sdf.org> wrote:
> > Paul Kraus <paul at kraus-haus.org> wrote:
> >> I typically run a scrub on any new drive after writing a bunch of data to it, specifically to look for infant mortality :-)
> > Looks like a good idea. Whenever I get the raidz2 set up and some
> > sizable amount of data loaded into it, I intend to do the same. However,
> > because the capacity of the 6-drive raidz2 will be about four times the
> > original UFS2 capacity, I suppose I'll need to find a way to expand the
> > dump file in other ways, so as to cover the misbehaving tracks on the
> > individual drives.
> I?m not sure I would worry about exercising the entire range of tracks on the platters, if a platter has a problem (heads or coating) it will likely show up all over the platter. If the problem is specific to a region, I would expect the drive to be able to remap the bad sectors (as we previously discussed).
I have no way of knowing where on the drive the long strings of errors
occurred except in the sense of which partition I was dealing with. Some
of the erroneous bytes were in groups of 100-300 bytes (roughly), which
means the errors were concentrated in a number places, as well as there
being many individual bytes scattered around the file. UFS2 puts blocks
where it will, so the groups could be anywhere in the partition and might
not always involve contiguous sectors.
> >> Don?t go by what *I* say, go the manufacturer?s web sites and download and read the full specifications on the drives you are looking at. None of the sales sites (Newegg, CDW, etc.) post the full specs, yet they are all (still) available from the Seagate / Western Digital / HGST etc. web sites.
> > Yes, I understood that from what you had already written. What I meant
> > was that I hadn't been aware that the manufacturers were selling the drives
> > divided into two differing grades of reliability. From now on, the issue
> > will be a matter of my budget vs. the price differences.
> Sorry If I was being overly descriptive, I am more of a math and science guy than an english guy, so my writing is often not the most clear. When I started buying Enterprise instead of Desktop drives the price difference was under $20 for a $100 drive. The biggest reason I started buying the Enterprise drives is that they are RATED for 24x7 operation, while Desktop are typically designed for 8x5 (but rarely do they say :-) While I do have my desktop and laptop systems setup to spin down the drives when not in use (and I leave some of them booted 24x7), my server(s) run 24x7 and THAT is where I pay for the Enterprise drives. I treat the drives in the laptop / desktop systems as disposable and do NOT keep any important data only on them (I rsync my laptop to the server a couple times per week and use TimeMachine when at the office).
> > Okay. Thanks again for the info. Just out of curiosity, where do you
> > usually find those Hitachi drives?
I saw Hitachi desktop drives at Fry's today, but no enterprise Hitachis.
> Newegg ? Once they lean red how to ship drives without destroying them I started buying drives from them :-)
I'm having some issues with newegg at present. One big bitch I have is
that their web site (like so unfortunately many others) requires the use of
an unsecured web browser to get them to work right, so I get help from friends
who are clueless about computer security. Then I spend two hours struggling
with their checkout procedure to complete a purchase and end up empty-handed
because the web site refuses to let me buy something at the special promotional
price sent to me via an email message. The next day (this past Friday) I
call newegg's customer [dis]service number and talk with a gal who tells
me that she can't find a problem but has just sent a message to their "IT"
department and will call me back after she gets a reply from that department.
She says that should be long before they closed for the holiday weekend.
Naturally, she did not call back, but that the particular item I asked about
would still be at the promotional price through Wed. this week, so there
would be plenty of time to straighten it out. Feh.
But today there is a new and pleasant development. The same email
message also had a promotional price for a 2 TB WD desktop internal drive
of ~$90 and the same drive in the enterprise grade level for ~$145. Next,
I checked the Fri. _Trib_ for the Fry's ad and found a sale price through
Wed. for the same desktop drive for $80. Beside that item in the ad pages,
there was a listing for the enterprise grade of the same drive, but said
to call them for prices. The surprise was that a friend went into the
suburbs today on other business and took me with him, so I could go to Fry's
on the way back. A few feet to the right on the same shelf as the $80
desktop drive was a bunch of the enterprise drives for...$90, the same price
that newegg wanted for the desktop drive and only $10 more than the desktop
drive's price at Fry's. 8--) So I bought one of the enterprise drives,
which I will use to replace a dead 1 TB WD drive in a WD MyBook case that
has USB 2.0, Firewire 400, and eSATA interfaces on it. :-)
So...one down and one more to go.
Scott Bennett, Comm. ASMELG, CFIAG
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