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location Boston, MA
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visits member for 4 years, 10 months
seen Apr 14 at 16:03

Feb
16
comment What are .nfs* on NFS mounts?
Unix only reclaims space when the link-count of a file is zero. When a file is opened, unix internally increments the link count. So, if you delete a file while it is open, the file must still exist until that file is closed. This is the NFS server's way of keeping the file around until that client's process closes the file and the server can reclaim the blocks / inodes from that file.
Feb
15
comment Raid 5 with hot spare or RAID 10 with no hot spare?
@zypher: the point is you've only got a limited number of disks in the array, and if you go raid 10 you don't have a hot spare. If you lose one disk, you've got a 33% chance of the next failure destroying 50% your data.
Feb
15
comment Raid 5 with hot spare or RAID 10 with no hot spare?
@chopper: If you lose a disk in R5, then rebuild from spare, then lose another, you now effectively have an intact raid0. That's 3 discrete disk failure events before you lose data. If you have a single simultaneous failure of more than one disk with R5, you're probably hosed (there's the tiny chance you'll lose the hot-spare, in which case you should also buy a lottery ticket...) With R10 and you have a simultaneous failure of 2 disks, you may be hosed.
Feb
15
comment Cooling requirements for POE switches?
Thanks for the link to hard numbers! The difference between the power draw of a POE+ and non-POE device can be 2x or 3x, and that makes a huge difference in the potential cooling required.
Jan
14
comment VMware NAS/iSCSI recommendations - smallish organization
That's the subject of lots of discussion but my experience is that convenience trumps performance, and that you'll have plenty of performance with 10gig ethernet either way.
Sep
3
comment Free alternative to Plesk
@David -- the email issues is definitely a concern, I'm just not sure how much of a concern given that if all my dns is down, I'm not sending outgoing email, relaying email, or accepting email. It would affect outgoing email that's been queued somewhere else and then accepted for delivery after the hypothetical network outtage, but that seems like a rare corner case.
Aug
21
comment Free alternative to Plesk
I've heard this many times, but I have to ask -- if my servers are in a single subnet, and that subnet vanishes from the internet, what's the advantage of having the names of my servers resolve? In other words -- what do I lose by having all my DNS servers running in the same network as my service providing servers? Granted -- I'd rather have redundancy, but if there is none for my servers, why do the DNS records need to be more reliable than the things they point to?
Aug
20
comment How exactly & specifically does layer 3 LACP destination address hashing work?
I think in your case the hash on destination won't get you anything since the switch will see the destination as your server. L2 traffic engineering just isn't very good. And 'hash' in this sort of application is going to be pretty primitive -- figure the best you can do is add up all the bits in whatever address(es) are in use and if the result is 0 go out one link or 1 go out the other.
Aug
18
comment How to reinstall a Server but have a message saying “Our website is currently down?”
So, yes, caching the wrong data may cause problems with weird clients that don't respect TTLs but I think those are getting rarer and rarer because so many things on the internet rely on short TTLs to properly deliver their dynamic (and interesting) content.
Aug
18
comment How to reinstall a Server but have a message saying “Our website is currently down?”
At this point so many things use tiny TTLs that I think it is a solved problem. Services like akamai seem to use a chain of 3 cnames, each with a 20-30 second TTL. www.apple.com, for instance, has the following cname chain: www.apple.com c -> ttl:1600 www.isg-apple.com.akadns.net. c -> ttl:30 www.apple.com.edgekey.net. c -> ttl:4096 e3191.c.akamaiedge.net. a -> ttl30 184.85.29.15
Aug
17
comment Network cables - make them or buy them
Wow. You're totally awesome.
Aug
16
comment Network cables - make them or buy them
You must have an expensive tester to have it test if it is cat3 vs cat5e vs cat6 that quickly. Mine takes almost a minute to run through the tests in cat6 mode.
Aug
16
comment Network cables - make them or buy them
As far as the cable tester -- you could run into situations where the link worked fine at 100mb and okay at gig without a large amount of traffic but when you try to use the system to push large amounts of traffic performance falls through the floor.
Aug
16
comment Network cables - make them or buy them
Network cards aren't like modems -- if the connection is poor they won't scale back to a lower speed, instead you'll just get lots of garbled packets and then the application will have to retransmit the packet later at a substantial loss of speed.
Aug
15
comment Any thoughts on 6 inch ethernet patch cables?
This really seems to be a common way of doing things, and I've seen it done well. It seems to be the approved of "panduit" way of organizing a rack, but in an organization like ours where lots of people make changes in racks, I'm afraid the 2 foot patch cables will get turned into a knot eventually.
Aug
15
comment Any thoughts on 6 inch ethernet patch cables?
@john: Other than being a judgmental scold, what was the specific answer to my question?
Aug
15
comment Any thoughts on 6 inch ethernet patch cables?
1. you're answer of "be like me and try harder" isn't actually all that helpful. 2. the rack pictured above isn't all that dense. Manage 100 of those 2 post rack with double the number of cables in less than the above space and put them into retrofitted broom closets, and have untrained helpdesk people manage adds and changes, thenn tell me about "a complete lack of a methodical approach to cabling".
Aug
15
comment Network cables - make them or buy them
Does your tester cost more or less than $3000? If it just checks pinouts, it is nearly worthless
Aug
13
comment Any thoughts on 6 inch ethernet patch cables?
How old is that rack and how much churn is there on that rack? The rack with the comically ugly wiring "organization" is about 5 years old and sees pretty constant change (though of only a small number of the ports). Everything looks great the first month it's in service...
Aug
5
comment Does it make sense to use 10Gbit Ethernet in a small business?
did you buy an arista switch? If so, how is it?