Are you truly new to ZFS? Or do you work for NetApp or EMC or somebody else that is curious?
- Mike On Aug 29, 2011, at 9:15 PM, Jesus Cea wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi all. Sorry if I am asking a FAQ, but I haven't found a really > authorizative answer to this. Most references are old, incomplete or > of "I have heard of" kind. > > I am running Solaris 10 Update 9, and my pool is v22. > > I recently got two 40GB SSD I plan to add to my pool. My idea is this: > > 1. Format each SSD as 39GB+1GB. > 2. Use the TWO 39GB's as L2ARC, with no redundancy. > 3. Use the TWO 1GB's as mirrored ZIL. > > 1GB of ZIL seems more than enough for my needs. I have synchronous > writes, but they are, 99.9% of the time, <1MB/s, with occasional bursts. > > My main concern here is about pool stability if there have any kind of > problem with the SSD's. Especifically: > > 1. Is the L2ARC data stored in the SSD checksummed?. If so, can I > expect that ZFS goes directly to the disk if the checksum is wrong?. > > 2. Can I import a POOL if one/both L2ARC's are not available?. > > 3. What happend if a L2ARC device, suddenly, "dissappears"?. > > 4. Any idea if L2ARC content will be persistent across system > rebooting "eventually"? > > 5. Can I import a POOL if one/both ZIL devices are not available?. My > pool is v22. I know that I can remove ZIL devices since v19, but I > don't know if I can remove them AFTER they are physically unavailable, > of before importing the pool (after a reboot). > > 6. Can I remove a ZIL device after ZFS consider it "faulty"?. > > 7. What if a ZIL device "dissapears", suddenly?. I know that I could > lose "committed" transactions in-fight, but will the machine crash?. > Will it fallback to ZIL on harddisk?. > > 8. Since my ZIL will be mirrored, I assume that the OS will actually > will look for transactions to be replayed in both devices (AFAIK, the > ZIL chain is considered done when the checksum of the last block is > not valid, and I wonder how this interacts with ZIL device mirroring). > > 9. If a ZIL device mirrored goes offline/online, will it resilver from > the other side, or it will simply get new transactions, since old > transactions are irrelevant after ¿30? seconds?. > > 10. What happens if my 1GB of ZIL is too optimistic?. Will ZFS use the > disks or it will stop writers until flushing ZIL to the HDs?. > > Anything else I should consider?. > > As you can see, my concerns concentrate in what happens if the SSDs go > bad or "somebody" unplugs them "live". > > I have backup of (most) of my data, but rebuilding a 12TB pool from > backups, in a production machine, in a remote hosting, would be > something I rather avoid :-p. > > I know that hybrid HD+SSD pools were a bit flacky in the past (you > lost the ZIL device, you kiss goodbye to your ZPOOL, in the pre-v19 > days), and I want to know what terrain I am getting into. > > PS: I plan to upgrade to S10 U10 when available, and I will upgrade > the ZPOOL version after a while. > > - -- > Jesus Cea Avion _/_/ _/_/_/ _/_/_/ > j...@jcea.es - http://www.jcea.es/ _/_/ _/_/ _/_/ _/_/ _/_/ > jabber / xmpp:j...@jabber.org _/_/ _/_/ _/_/_/_/_/ > . _/_/ _/_/ _/_/ _/_/ _/_/ > "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ > "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ > "El amor es poner tu felicidad en la felicidad de otro" - Leibniz > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.10 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iQCVAwUBTlxjxplgi5GaxT1NAQLi9AP/VW2LQqij6y25KQ3c5EDBWvnnL1Z7R65j > BJ0N1EbWW6ZdkQ9uFoLNJBVb8xPgwpTOKuy5g8FTwrjs1Sc5a3E3DbRDUg75faE5 > 4IOgCi0gtIVyrxGEQ2AAhnKHGcto/2gB9Y5KRiibBeysbqNvr0HXQsko7WRauP96 > N1L1TqFsN8E= > =sDRY > -----END PGP SIGNATURE----- > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
